Patent Publication Number: US-2020281278-A1

Title: System and method for measuring payload dosage in a vaporization device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority to U.S. Provisional Application Ser. No. 62/813,845, filed on Mar. 5, 2019, and U.S. Provisional Application Ser. No. 62/899,828, filed on Sep. 13, 2019, each of which is incorporated herein by reference in its entirety. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure is generally related to the field of personal vaporizer devices and, in particular, to systems and methods for measuring the dosage of a vaporized payload that is delivered to the user of a personal vaporizer device. 
     2. Description of Related Art 
     The use of personal vaporizer devices or “vape devices” for consuming  cannabis , tobacco products, and other substances has grown significantly. In a basic form, a vape device consists of an atomizer, a battery, a switch for connecting the battery to the atomizer, and a reservoir that contains an amount of payload (e.g.,  cannabis  oil) to be vaporized by the atomizer. Controlling the vape device merely entails closing the switch so that current passes from the battery through a coil of the atomizer whereby the atomizer heats up and begins to vaporize a portion of the payload. The vapor—i.e., the cloud-like emission from a vape device that may be some combination of actual gas phase vapor and aerosol—is then inhaled by the user so that the desired components (e.g., THC, CBD, etc.) are delivered for medical or recreational purposes. 
     While there are a few conventional vape devices that attempt to determine the dosage of a vaporized payload delivered to a user, they use inaccurate methods that offer poor dose metering performance. It is technically difficult to accurately measure the dose administered by a vape device because, for example, vapor density can be inconsistent and operating conditions will vary. As such, medicinal patients are unsure of the dosage that they have consumed at any given time, which limits the repeatability and efficacy of the drug&#39;s effects. Also, recreational users may experience different effects (desirable and undesirable) depending on dosage. Thus, there remains a need in the art for a vape device that accurately measures the dose of a payload delivered to a user and/or that offers other advantages compared to conventional vape devices. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is directed to a vape device for determining the dose of a payload delivered to a user during each of a plurality of user inhalations (commonly referred to as a “draw” or “drag” or “puff”). The vape device may use four different methods, independently or in any combination, to measure the portion of the payload that is vaporized during each user inhalation. The first method tracks the energy used to vaporize the payload portion during user inhalation in order to determine the mass of the vaporized payload; the second method measures the temperature at multiple locations within the air flow chamber during the user inhalation (and optionally before and after the user inhalation) to determine the vapor density and by extension the mass of the vaporized payload; the third method measures the intensity of light that is transmitted through the vaporized payload, reflected off the vaporized payload, or transmitted through a light transmitting medium positioned within the vaporized payload, before, during, and after user inhalation to determine the vapor density and by extension the mass of the vaporized payload; and the fourth method utilizes hot wire anemometers to determine the mass of the vaporized payload that was delivered to the user during each user inhalation and/or to determine the size and density distribution of the droplets in the vaporized payload and use such distribution to calculate the total mass of the vaporized payload that was delivered to the user during each user inhalation. More accurate dose metering is beneficial to both medicinal and recreational users insofar as they will be able to accurately measure their dosage to obtain the desired effects in a repeatable fashion. 
     A vape device for determining a dose of a payload delivered to a user during each of a plurality of user inhalations in accordance with one exemplary embodiment of the invention described herein comprises: a payload reservoir configured to contain a payload to be vaporized; a power source configured to generate a power signal during each respective user inhalation; an atomizer configured to receive the power signal and vaporize a portion of the payload to thereby generate a vaporized payload during each respective user inhalation; and a microcontroller programmed to determine a dose of the vaporized payload for each respective user inhalation based on: (a) determining an amount of energy used to vaporize the portion of the payload during the user inhalation; and (b) determining a partial mass of the payload that is vaporized during the user inhalation based on the amount of energy used to vaporize the portion of the payload during the user inhalation. 
     A method for determining a dose of a payload delivered to a user of a vape device during each of a plurality of user inhalations in accordance with another exemplary embodiment of the invention described herein comprises: holding a payload to be vaporized; vaporizing a portion of the payload by transmitting a power signal from a power source to an atomizer to thereby generate a vaporized payload during each respective user inhalation; and determining a dose of the vaporized payload for each respective user inhalation based on: (a) determining an amount of energy used to vaporize the portion of the payload during the user inhalation; and (b) determining a partial mass of the payload that is vaporized during the user inhalation based on the amount of energy used to vaporize the portion of the payload during the user inhalation. 
     A vape device for determining a dose of a payload delivered to a user during each of a plurality of user inhalations in accordance with another exemplary embodiment of the invention described herein comprises: a payload reservoir configured to contain a payload to be vaporized; an air flow chamber that extends between an inlet and an outlet; an atomizer positioned between the inlet and the outlet of the air flow chamber, wherein the atomizer is configured to vaporize a portion of the payload to thereby generate a vaporized payload during each respective user inhalation; and a microcontroller programmed to determine a dose of the vaporized payload for each respective user inhalation based on: (a) a plurality of temperature measurements obtained within the air flow chamber during the user inhalation; and (b) an air flow rate within the air flow chamber during the user inhalation. 
     A method for determining a dose of a payload delivered to a user of a vape device during each of a plurality of user inhalations in accordance with another exemplary embodiment of the invention described herein comprises: holding a payload to be vaporized; vaporizing a portion of the payload with an atomizer positioned between an inlet and an outlet of an air flow chamber to thereby generate a vaporized payload during each respective user inhalation; and determining a dose of the vaporized payload for each respective user inhalation based on: (a) a plurality of temperature measurements obtained within the air flow chamber during the user inhalation; and (b) an air flow rate within the air flow chamber during the user inhalation. 
     A vape device for determining a dose of a payload delivered to a user during each of a plurality of user inhalations in accordance with another exemplary embodiment of the invention described herein comprises: a payload reservoir configured to contain a payload to be vaporized; an air flow chamber that extends between an inlet and an outlet; an atomizer positioned between the inlet and the outlet of the air flow chamber, wherein the atomizer is configured to vaporize a portion of the payload to thereby generate a vaporized payload during each respective user inhalation; and a microcontroller programmed to determine a dose of the vaporized payload for each respective user inhalation based on a plurality of light intensity measurements obtained during the user inhalation, wherein the light intensity measurements are associated with light that is transmitted through the vaporized payload, reflected off the vaporized payload, or transmitted through a light transmitting medium positioned within the vaporized payload, when the vaporized payload passes through the air flow chamber. 
     A method for determining a dose of a payload delivered to a user of a vape device during each of a plurality of user inhalations in accordance with another exemplary embodiment of the invention described herein comprises: holding a payload to be vaporized; vaporizing a portion of the payload with an atomizer positioned between an inlet and an outlet of an air flow chamber to thereby generate a vaporized payload during each respective user inhalation; and determining a dose of the vaporized payload for each respective user inhalation based on a plurality of light intensity measurements obtained during the user inhalation, wherein the light intensity measurements are associated with light that is transmitted through the vaporized payload, reflected off the vaporized payload, or transmitted through a light transmitting medium positioned within the vaporized payload, when the vaporized payload passes through the air flow chamber. 
     A vape device for determining a dose of a payload delivered to a user during each of a plurality of user inhalations in accordance with another exemplary embodiment of the invention described herein comprises: a payload reservoir configured to contain a payload to be vaporized; an air flow chamber that extends between an inlet and an outlet; an atomizer located between the inlet and the outlet of the air flow chamber, wherein the atomizer is configured to vaporize a portion of the payload to thereby generate a vaporized payload during each respective user inhalation; at least one sampling hot wire anemometer located within the air flow chamber between the atomizer and the outlet, wherein the sampling hot wire anemometer is incorporated into a circuit configured to determine a number of droplets of the vaporized payload passing by the sampling hot wire anemometer during each respective user inhalation; and a microcontroller programmed to determine a dose of the vaporized payload for each respective user inhalation based on the number of droplets of the vaporized payload. 
     A method for determining a dose of a payload delivered to a user of a vape device during each of a plurality of user inhalations in accordance with another exemplary embodiment of the invention described herein comprises: holding a payload to be vaporized; vaporizing a portion of the payload with an atomizer positioned between an inlet and an outlet of an air flow chamber to thereby generate a vaporized payload during each respective user inhalation; determining a number of droplets of the vaporized payload passing by at least one sampling hot wire anemometer located within the air flow chamber between the atomizer and the outlet during each respective user inhalation; and determining a dose of the vaporized payload for each respective user inhalation based on the number of droplets of the vaporized payload. 
     Various other embodiments and features of the present invention are described in detail below with reference to the attached drawing figures, or will be apparent to those skilled in the art based on the disclosure provided herein, or may be learned from the practice of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a first embodiment of a vape device in accordance with the invention described herein. 
         FIG. 2  is a schematic diagram of a second embodiment of a vape device in accordance with the invention described herein. 
         FIG. 3  is a schematic diagram of an embodiment of a vape device system that includes the vape device of  FIG. 1  in wireless communication with a personal computing device. 
         FIG. 4  is a schematic diagram of an exemplary vape device that utilizes an energy usage method to determine the dose of vaporized payload delivered to a user. 
         FIG. 5  is a schematic diagram of an exemplary vape device that utilizes a temperature measurement method to determine the dose of vaporized payload delivered to a user. 
         FIGS. 6-13  are schematic diagrams of exemplary vape devices that utilize various light intensity measurement methods to determine the dose of vaporized payload delivered to a user. 
         FIG. 14  is a schematic diagram of an exemplary vape device that utilizes hot wire anemometers to determine the dose of vaporized payload delivered to a user. 
         FIG. 15  is a block diagram of exemplary components that may be incorporated into a vape device to determine the dose of vaporized payload delivered to a user and to determine the size and density distribution of the droplets in the vaporized payload. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION 
     The present invention is directed to a vape device for determining the dose of a payload delivered to a user during each of a plurality of user inhalations. While the invention will be described in detail below with reference to various exemplary embodiments, it should be understood that the invention is not limited to the specific configuration or methodologies of any of these embodiments. In addition, although the exemplary embodiments are described as embodying several different inventive features, those skilled in the art will appreciate that any one of these features could be implemented without the others in accordance with the invention. 
     In this description, references to “one embodiment,” “an embodiment,” “an exemplary embodiment,” or “embodiments” mean that the feature or features being described are included in at least one embodiment of the invention. Separate references to “one embodiment,” “an embodiment,” “an exemplary embodiment,” or “embodiments” in this description do not necessarily refer to the same embodiment and are also not mutually exclusive unless so stated and/or except as will be readily apparent to those skilled in the art from the description. For example, a feature, structure, function, etc. described in one embodiment may also be included in other embodiments, but is not necessarily included. Thus, the present invention can include a variety of combinations and/or integrations of the embodiments described herein. 
     In this disclosure, the term “payload” refers to any payload suitable for a vape device. Non-limiting examples include a payload comprising nicotine,  cannabis , a cannabinoid or a  cannabis  concentrate as an ingredient. The payload may include other components such as, without limitation, a viscosity modifying agent, a stabilizer, and a flavorant. 
     As used herein, the term “nicotine” can be of plant origin or of synthetic or semi-synthetic origin. For example, it can be extracted from tobacco leaves or obtained by chemical synthesis. Nicotine may also refer to a nicotine substitute, which is typically a molecule that is not addictive but has a sensory effect similar to that of nicotine. 
     As used herein, the term “ cannabis ” refers to a genus of flowering plant in the family Cannabaceae. The number of species within the genus is disputed. Three species may be recognized,  Cannabis sativa, Cannabis  indica and  Cannabis ruderalis. C. ruderalis  may be included within  C. sativa ; or all three may be treated as subspecies of a single species,  C. sativa . The genus is indigenous to central Asia and the Indian subcontinent. 
       Cannabis  has long been used for hemp fiber, hemp oils, medicinal purposes, and as a recreational drug. Industrial hemp products are made from  cannabis  plants selected to produce an abundance of fiber. To satisfy the UN Narcotics Convention, some  cannabis  strains have been bred to produce minimal levels of tetrahydrocannabinol (THC), the principal psychoactive constituent. Many additional plants have been selectively bred to produce a maximum level of THC. Various compounds, including hashish and hash oil, may be extracted from the plant. 
     Within naturally occurring and manmade hybrids,  cannabis  contains a vast array of compounds. Three compound classes are of interest within the context of the present disclosure, although other compounds can be present or added to the compositions to optimize the experience of a given recreational consumer and medical or medicinal patient or patient population. Those classes include cannabinoids, terpenes and flavonoids. 
     There are many ways of growing  cannabis , some of which are natural, and some are carefully designed by humans, and they will not be recited here. However, one of ordinary skill in the art of  cannabis  production will typically place a  cannabis  seed or cutting into a growth media such as soil, manufactured soil designed for  cannabis  growth or one of many hydroponic growth media. The  cannabis  seed or cutting is then provided with water, light and, optionally, a nutrient supplement. At times, the atmosphere and temperature are manipulated to aid in the growth process. Typically, the humidity, air to carbon dioxide gas ratio and elevated temperature, either by use of a heat source or waste heat produced by artificial light, are used. On many occasions ventilation is carefully controlled to maintain the conditions described above within an optimal range to both increase the rate of growth and, optionally, maximize the plant&#39;s production of the compounds, which comprise the compositions of the disclosure. It is possible to control lighting cycles to optimize various growth parameters of the plant. 
     Given the number of variables and the complex interaction of the variables, it is possible to develop highly specific formulas for production of  cannabis  which lead to a variety of desired plant characteristics. The present disclosure is applicable to use with such inventive means for growing  cannabis  as well as any of the variety of conventional methods. 
       Cannabis sativa  is an annual herbaceous plant in the  Cannabis  genus. It is a member of a small, but diverse family of flowering plants of the Cannabaceae family. It has been cultivated throughout recorded history, used as a source of industrial fiber, seed oil, food, recreation, religious and spiritual moods and medicine. Each part of the plant is harvested differently, depending on the purpose of its use. The species was first classified by Carl Linnaeus in 1753. 
       Cannabis  indica, formally known as  Cannabis sativa  forma indica, is an annual plant in the Cannabaceae family. A putative species of the genus  Cannabis.    
       Cannabis ruderalis  is a low-THC species of  Cannabis , which is native to Central and Eastern Europe and Russia. It is widely debated as to whether  C. ruderalis  is a sub-species of  Cannabis sativa . Many scholars accept  Cannabis ruderalis  as its own species due to its unique traits and phenotypes that distinguish it from  Cannabis  indica and  Cannabis sativa.    
     As used herein, the term “cannabinoid” refers to a chemical compound belonging to a class of secondary compounds commonly found in plants of genus  cannabis , but also encompasses synthetic and semi-synthetic cannabinoids. 
     The most notable cannabinoid is tetrahydrocannabinol (THC), the primary psychoactive compound in  cannabis . Cannabidiol (CBD) is another cannabinoid that is a major constituent of the phytocannabinoids. There are at least 113 different cannabinoids isolated from  cannabis , exhibiting varied effects. 
     Synthetic cannabinoids and semi-synthetic cannabinoids encompass a variety of distinct chemical classes, for example and without limitation: the classical cannabinoids structurally related to THC, the non-classical cannabinoids (cannabimimetics) including the aminoalkylindoles, 1,5 diarylpyrazoles, quinolines, and arylsulfonamides as well as eicosanoids related to endocannabinoids. 
     In many cases, a cannabinoid can be identified because its chemical name will include the text string “*cannabi*”. However, there are a number of cannabinoids that do not use this nomenclature. 
     Within the context of this disclosure, where reference is made to a particular cannabinoid, each of the acid and/or decarboxylated forms are contemplated as both single molecules and mixtures. In addition, salts of cannabinoids are also encompassed, such as salts of cannabinoid carboxylic acids. 
     As well, any and all isomeric, enantiomeric, or optically active derivatives are also encompassed. In particular, where appropriate, reference to a particular cannabinoid includes both the “A Form” and the “B Form”. For example, it is known that THCA has two isomers, THCA-A in which the carboxylic acid group is in the 1 position between the hydroxyl group and the carbon chain (A Form) and THCA-B in which the carboxylic acid group is in the 3 position following the carbon chain (B Form). 
     Examples of cannabinoids include, but are not limited to: cannabigerolic acid (CBGA), cannabigerolic acid monomethylether (CBGAM), cannabigerol (CBG), cannabigerol monomethylether (CBGM), cannabigerovarinic acid (CBGVA), cannabigerovarin (CBGV), cannabichromenic Acid (CBCA), cannabichromene (CBC), cannabichromevarinic Acid (CBCVA), cannabichromevarin (CBCV), cannabidiolic acid (CBDA), cannabidiol (CBD), Δ6-cannabidiol (Δ6 CBD), cannabidiol monomethylether (CBDM), cannabidiol-C4 (CBD-C4), cannabidivarinic Acid (CBDVA), cannabidivarin (CBDV), cannabidiorcol (CBD-C1), tetrahydrocannabinolic acid A (THCA-A), tetrahydrocannabinolic acid B (THCA-B), tetrahydrocannabinol (THC or Δ9-THC), Δ8 tetrahydrocannabinol (Δ8-THC), trans-410-tetrahydrocannabinol (trans-Δ10-THC), cis Δ10-tetrahydrocannabinol (cis-Δ10-THC), tetrahydrocannabinolic acid C4 (THCA-C4), tetrahydrocannbinol C4 (THC C4), tetrahydrocannabivarinic acid (THCVA), tetrahydrocannabivarin (THCV), Δ8-tetrahydrocannabivarin (Δ8-THCV), Δ9 tetrahydrocannabivarin (Δ9-THCV), tetrahydrocannabiorcoli c acid (THCA-C1), tetrahydrocannabiorcol (THC-C1), Δ7-cis-iso-tetrahydrocannabivarin, Δ8 tetrahydrocannabinolic acid (Δ8-THCA), Δ9-tetrahydrocannabinolic acid (Δ9-THCA), cannabicyclolic acid (CBLA), cannabicyclol (CBL), cannabicyclovarin (CBLV), cannabielsoic acid A (CBEA-A), cannabielsoic acid B (CBEA-B), cnnabielsoin (CBE), cannabinolic acid (CBNA), cannabinol (CBN), cannabinol methylether (CBNM), cannabinol-C4 (CBN-C4), cannabivarin (CBV), cannabino-C2 (CBN-C2), cannabiorcol (CBN-C1), cannabinodiol (CBND), cannabinodivarin (CBDV), cannabitriol (CBT), 11 hydroxy-Δ9-tetrahydrocannabinol (11-OH-THC), 11 nor 9-carboxy-δ9-tetrahydrocannabinol, ethoxy-cannabitriolvarin (CBTVE), 10 ethoxy-9-hydroxy-δ6a-tetrahydrocannabinol, cannabitriolvarin (CBTV), 8,9 dihydroxy-Δ6a(10a)-tetrahydrocannabinol (8,9-Di-OH-CBT-C5), dehydrocannabifuran (DCBF), cannbifuran (CBF), cannabichromanon (CBCN), cannabicitran (CBT), 10 oxo-Δ6a(10a)-tetrahydrocannabinol (OTHC), Δ9 cis tetrahydrocannabinol (cis THC), cannabiripsol (cbr), 3,4,5,6-tetrahydro-7-hydroxy-alpha-alpha-2-trimethyl-9-n-propyl-2,6-methano-2h-1-benzoxocin-5-methanol (OH-iso-HHCV), trihydroxy-delta-9-tetrahydrocannabinol (triOH-THC), yangonin, epigallocatechin gallate, dodeca-2e, 4e, 8z, 10z-tetraenoic acid isobutylamide, hexahydrocannibinol, and dodeca-2e,4e-dienoic acid isobutylamide. 
     In some embodiments of the present disclosure, the cannabinoid is a cannabinoid dimer. The cannabinoid may be a dimer of the same cannabinoid (e.g., THC-THC) or different cannabinoids. In an embodiment of the present disclosure, the cannabinoid may be a dimer of THC, including for example cannabisol. 
     As used herein, the term “ cannabis  concentrate” refers to a mixture of compounds that is obtained from a  cannabis  plant, such as for example a mixture of compounds or compositions that have been extracted from  cannabis . The  cannabis  concentrate may be a concentrated composition of  cannabis -derived cannabinoids, terpenes, terpenoids, and other naturally occurring compounds found in the  cannabis  plant. Non-limiting embodiments of a  cannabis  concentrate include a  cannabis  distillate, a  cannabis  isolate, a  cannabis  resin, a  cannabis  derived cannabinoid, or any other type of extract containing one or more cannabinoids or terpenes, terpenoids, and other naturally occurring compounds found in the  cannabis  plant. 
     As used herein, the term “viscosity control agent” describes a substance for controlling and maintaining the viscosity of the payload. Non-limiting embodiments of a viscosity control agent include propylene glycol (1,2-propanediol), 1,3-propanediol, polyethylene glycol, vegetable glycerin, a terpene, triacetin, diacetin and triethyl citrate. 
     As used herein, the term “stabilizer” is any substance used to prevent an unwanted change in state. The stabilizer may be used to improve or maintain the stability of the payload. For example, without a stabilizer, cannabinoids or  cannabis  concentrates may be susceptible to degradation, such as oxidative degradation, cannabinoids may crystallize out of the payload, and/or the payload may undergo color change. 
     As used herein, the term “flavorant” is used to describe a compound or combination of compounds that may provide flavor and/or aroma to the payload. The flavorant may include at least one of a natural flavorant or an artificial flavorant. Non-limiting embodiments of a flavorant may be a tobacco flavor, menthol, wintergreen, peppermint, herb flavors, fruit flavors, nut flavors, liquor flavors and terpene flavors. 
     I. Vape Device 
     The present invention is directed to a vape device that measures and preferably controls or meters the dose of vaporized payload inhaled by the user. The dose metering technology may be incorporated into a variety of different types of vape devices available in various sizes in terms of the amount of payload they can contain. In one embodiment, the vape device comprises a self-contained vape device, e.g., a one piece disposable vape device in which all of the components are contained within a single housing. In another embodiment, the vape device comprises a control assembly and cartridge that are formed in separate housings and releasably connected to each other via an electromechanical connection. In this embodiment, the control assembly is provided as a re-useable component that can be used with multiple disposable cartridges. In yet another embodiment, the vape device comprises a tabletop or desktop vaporizer. 
     Various embodiments of vape devices that may incorporate the dose metering technology of the present invention are described below in connection with  FIGS. 1-3 . In some embodiments, the vape devices can communicate with a personal computing device and work interactively with an application or “app” operating on the personal computing device to provide additional functions and features that enable implementation of certain aspects of the invention. Of course, it should be understood that the present invention is not limited to these embodiments and that other types of vape devices may also be used within the scope of the invention. 
     For the sake of simplicity, the vape devices described in connection with  FIGS. 1-3  are provided to describe the general structural configuration of the vape devices and do not include all of the various components and circuits required to provide the dose metering technology of the present invention; rather, these components and circuits are described below in connection with the vape devices shown in  FIGS. 4-10 . 
     First Embodiment of Vape Device 
     Referring to  FIG. 1 , a first embodiment of a vape device is shown generally as reference numeral  10 . Vape device  10  includes a mouthpiece assembly  12 , an atomizer assembly  19 , a payload assembly  24 , and a control assembly  14 . Any of mouthpiece assembly  12 , atomizer assembly  19 , payload assembly  24 , and control assembly  14  may be formed integrally together and included within a common housing suitable for grasping by a user. Further, any of mouthpiece assembly  12 , atomizer assembly  19 , payload assembly  24 , and control assembly  14  may be formed in separate housings that are releasably connected to each other via connecting means  15 , which can comprise, for example, one or more of pressure or friction fit connection means, twist mechanical lock means, magnetic connection means and any other connecting means as well known to those skilled in the art. The connecting means  15  may include a female  510  threaded connector on the control assembly  14  that releasably engages a male  510  threaded connector on the atomizer assembly  19  or payload assembly  24 . A  510  threaded connector, as is known in the art, is a M7-0.5×5 threaded connector, i.e., a threaded connector with a nominal diameter of 7 mm, a pitch of 0.5 mm, and a length of 5 mm. Connecting means  15  may include threaded connectors of other sizes. By way of example, mouthpiece assembly  12  may be releasably connected to atomizer assembly  19 , payload assembly  24  and control assembly  14 , which are either formed integrally together or in separate housings that are releasably connected to each other. Mouthpiece assembly  12  and atomizer assembly  19  may be formed integrally together and releasably connected to payload assembly  24  and control assembly  14 , which are either formed integrally together or in separate housings that are releasably connected to each other. Further, mouthpiece assembly  12 , atomizer assembly  19 , and payload assembly  24  may be formed integrally together and releasably connected to control assembly  14 . The combination of the mouthpiece assembly  12 , atomizer assembly  19 , and payload assembly  24  may be referred to as a cartridge herein. It is also within the scope of the invention for the mouthpiece assembly  12  to be omitted and for the vaporized payload to exit the atomizer assembly  19  directly for inhalation. 
     In some embodiments, a heater or atomizer  20  is disposed in atomizer assembly  19 , with atomizer  20  further comprising a heating element  22  disposed therein for heating and vaporizing a payload that may comprise, for example, liquids, oils or other fluids (e.g.,  cannabis  oil or nicotine oil). Vape device  10  may also be modified to vaporize a tablet of dry material or dry material that is not in tablet form (e.g., ground  cannabis  bud). Heating element  22  may be a heating coil. Atomizer  20  can comprise an inlet  21  and an outlet  23 , wherein inlet  21  can be in communication, via fluid connector  46 , with payload reservoir  26  disposed in payload assembly  24 , wherein payload reservoir  26  can contain a payload for vaporization or atomization. Outlet  23  can be in communication with a user mouthpiece  16  of mouthpiece assembly  12  via a conduit  17 , which is typically a hollow tube made of stainless steel, aluminum, or other materials known to those skilled in the art. It will be understood to those skilled in the art that an air path will extend through atomizer assembly  19  and mouthpiece assembly  12  allowing ambient air to flow from an air inlet (not shown) of atomizer  20  and through conduit  17  to user mouthpiece  16 . 
     In some embodiments, payload assembly  24  contains a memory device  28 . Memory device  28  may be any type of device that includes memory or storage capable of storing a unique payload identifier that identifies payload reservoir  26  and/or other information related to the payload contained in payload reservoir  26 , as discussed below. Memory device  28  also includes means for allowing the stored information to be retrieved by another device. For example, memory device  28  may be wired (e.g., EEPROM or flash memory), wireless (e.g., a radio frequency identification (RFID) tag or near field communications (NFC) tag), or a combination of wired and wireless (e.g., wired through one interface and wireless through another interface). Microcontroller  31  may process the information retrieved from memory device  28  and/or transmit the information to an external computing device via a radio frequency (RF) transceiver circuit  36  and antenna(s)  40 . In one embodiment, memory device  28  comprises an integrated circuit (IC) chip for modulating and demodulating radio frequency signals, such as a galvanically isolated NFC tag that can be read by any NFC-capable device. In one embodiment, the NFC tag is read directly by an external computing device, such as personal computing device  72  described below. Of course, other short-range wireless technologies may also be used in accordance with the present invention. 
     In some embodiments, atomizer  20  can be disposed in atomizer assembly  19  that can either be integral to mouthpiece assembly  12 , or a physically separate enclosure that can couple to mouthpiece assembly  12 . Instead of or in addition to including a heating element  22  as disclosed herein, atomizer  20  may include any other structure capable of vaporizing or atomizing a payload in a suitable form for inhalation. For example, atomizer  20  may include a jet nebulizer, an ultrasonic nebulizer, or a mesh nebulizer. 
     In some embodiments, payload reservoir  26  and memory device  28  can be disposed in payload assembly  24  that can either be integral to mouthpiece assembly  12  and/or atomizer assembly  19 , or a physically separate enclosure that can couple to mouthpiece assembly  12  and/or atomizer assembly  19 , which can include one or more of connecting means  15  described above. Preferably, memory device  28  is physically coupled to payload reservoir  26  either directly or indirectly (e.g., memory device  28  and payload reservoir  26  are included in a common housing of payload assembly  24 ) in a tamper resistant manner. 
     In some embodiments, control assembly  14  can comprise one or more antennas  40 , a power source such as battery  42 , and a printed circuit board  30  that can further comprise a microcontroller  31  configured for carrying out one or more electronic functions in respect of the operation of vape device  10 . Having more than one antenna  40  can enable the ability for diversity wireless communications of RF signals, as well known to those skilled in the art. In some embodiments, battery  42  can comprise a lithium ion power cell battery, although other battery technologies can be used as well known to those skilled in the art. As the vape devices are personal use devices, the battery  42  can comprise technology that prevents the advent of an explosion should the battery fail. 
     In some embodiments, circuit board  30  can comprise a charger circuit  32  configured for charging battery  42 . Charger circuit  32  can be integral to circuit board  30  or can be disposed on a separate circuit board operatively connected to circuit board  30  and to battery  42  via electrical connection  54 . Charger circuit  32  can be configured to be operatively connected to an external source of power, either via a shared or dedicated electrical connector  35  operatively coupled to circuit board  30  with internal connection to charger circuit  32 , or a wireless connection for power transfer, as well known to those skilled in the art. Charger circuit  32  may also connect to electrical connection  50  as a means of charging. 
     In some embodiments, circuit board  30  can comprise user input interface circuit  34  and output interface circuit  38 . Either or both of input interface circuit  34  and output interface circuit  38  can be integral to circuit board  30  or can be disposed on a separate circuit board operatively connected to circuit board  30 . In some embodiments, input interface circuit  34  can provide the electrical interface between user controls and activation mechanisms disposed on vape device  10 , such as buttons, switches, draw sensors, pressure transducers, proximity sensors, flow sensors, touch sensors, voice recognition sensors, haptic controls, saliva and breath biosensors, and the like, and microcontroller  31  and, thus, can provide the means to relay user input commands from the user controls as instructions to microcontroller  31  to operate vape device  10 . 
     For example, input interface circuit  34  may be electrically coupled to a draw sensor  18  for receiving an “on” signal from draw sensor  18  when a user draws on mouthpiece  16 . When input interface circuit  34  receives the “on” signal from draw sensor  18 , it may send instructions to microcontroller  31  to cause supply of a controlled current or voltage to heating element  22  and thereby provide vapor through outlet  23 , provided that any other conditions necessary to activate atomizer  20  have been met. In some embodiments, draw sensor  18  comprises a sensor, such as a mass air flow sensor, that can produce an electrical signal in response to when a user inhales or draws on mouthpiece  16 , wherein the electrical signal can cause the power signal to flow from battery  42  through heating element  22 . In some embodiments, draw sensor  18  can be used as a simple “switch” as a means to turn on atomizer  20  to vaporize payload drawn into atomizer  20  from payload reservoir  26  as the user draws on mouthpiece  16 . Draw sensor  18  is one type of activation mechanism that may be used to activate atomizer  20 . Draw sensor  18  may be replaced with or used in connection with another type of activation mechanism that receives an input to switch it from an “off” position, in which atomizer  20  is not activated, and an “on” position, in which atomizer  20  is activated. For example, draw sensor  18  may be replaced with or used in connection with any of the following types of activation mechanisms: a button, switch, pressure transducer, proximity sensor, flow sensor, touch sensor, voice recognition sensor, haptic control, saliva and breath biosensor, and the like. 
     In some embodiments, output interface circuit  38  can provide the electrical interface between microcontroller  31  and output display devices, such as indicator lights, alphanumeric display screens, audio speakers, surface heaters, vibration devices, and any other forms of tactile feedback devices as well known to those skilled in the art, and, thus, can provide the means to relay information relating to the operation of vape device  10  from microcontroller  31  to the user. 
     In some embodiments, circuit board  30  can comprise an RF transceiver circuit  36  to provide the means for wireless communication of data between vape device  10  and a personal computing device, such as personal computing device  72  as shown in  FIG. 3 . In some embodiments, RF transceiver circuit  36  can be integral to circuit board  30  or can be disposed on a separate circuit board operatively connected to circuit board  30 . RF transceiver circuit  36  can be connected to one or more antennas  40  via electrical connection  52 , as well known to those skilled in the art. RF transceiver circuit  36  and the one or more antennas  40  comprise a wireless transceiver of vape device  10 . 
     In some embodiments, microcontroller  31  can comprise a microprocessor (which for purposes of this disclosure also incorporates any type of processor) having a central processing unit as well known to those skilled in the art, wherein the microprocessor can further comprise a memory configured for storing a series of instructions for operating the microprocessor in addition to storing data collected from sensors disposed on vape device  10  or data received by vape device  10  to control its operation, such as operational settings. Microcontroller  31  is in electrical communication with charger circuit  32 , user input interface circuit  34 , output interface circuit  38 , and RF transceiver circuit  36  for receiving instructions and/or data from and/or transmitting instructions and/or data to charger circuit  32 , user input interface circuit  34 , output interface circuit  38 , and RF transceiver circuit  36 . 
     In some embodiments, atomizer  20  can be operatively and electrically connected to circuit board  30  via electrical connection  48 , which can provide the means to activate atomizer  20  (e.g., deliver electrical current from battery  42  to heating element  22 ) when an activation mechanism such as draw sensor  18  sends an “on” signal to microcontroller  31 , as well as receiving data signals from draw sensor  18  and/or atomizer  20 . In this manner, the activation mechanism (i.e., draw sensor  18 ) is coupled to the atomizer  20  indirectly through microcontroller  31 , and a direct connection between the activation mechanism and atomizer  20  is not required (i.e., the activation mechanism sends a signal to microcontroller  31  which sends a signal to activate atomizer  20 ). In addition to controlling operation of atomizer  20  based on a signal received from the activation mechanism, microcontroller  31  also controls operation of atomizer  20  based on the operational settings described below. In some embodiments, microcontroller  31  can be operatively connected to memory device  28  via electrical connection  50 . 
     As used herein, the term “electrical connection” shall include any form of electrical connection via a wired or wireless connection, such as electrical conductors or wires suitable for the transmission of a power signal (e.g., a direct current or pulsed direct current), analog or digital electrical signals or radio frequency signals, as the case may be and as well-known to those skilled in the art. 
     The operational settings referred to herein include any type of setting or instruction that instructs the vape device  10  or certain components of the vape device  10  to operate or not operate in a particular manner. Specifically, operational settings of the vape device  10  include one or more of a duty cycle setting, a temperature setting, an operational time duration, a dosage setting, and a security setting. The duty cycle setting preferably corresponds to a pulse width modulation instruction transmitted from microcontroller  31  to battery  42  to send electrical current to heating element  22  in a particular desired manner. The temperature setting preferably corresponds to a temperature instruction transmitted from microcontroller  31  to battery  42  to send electrical current to heating element  22  to maintain heating element  22  at a desired temperature or range of temperatures. A temperature sensor may be coupled to microcontroller  31  to measure the actual temperature of heating element  22  and transmit that information to microcontroller  31  for determination of the amount and duration of electrical current that needs to be sent to heating element  22  to maintain a particular temperature or range of temperatures. The operational time duration preferably corresponds to a time instruction transmitted from microcontroller  31  to battery  42  to maintain heating element  22  at a temperature suitable for vaporization of the contents of payload reservoir  26  for a desired time. The dosage setting preferably corresponds to a dosage instruction transmitted from microcontroller  31  to battery  42  that powers down heating element  22  when a desired volume of vapor passes through atomizer  20 . As described in greater detail below, various dose metering methods may be used to accurately measure the volume of vaporized payload passing through atomizer  20  to mouthpiece  16  for user inhalation, whereby microcontroller  31  compares the actual volume passed through atomizer  20  to the dosage setting to determine when to shut off heating element  22 . 
     In some embodiments, memory device  28  and/or microcontroller  31 , along with appropriate sensors, can also be used as part of a system for gathering data relating to the use of vape device  10  by the user by monitoring that can include, without limitation, historical vape device usage information, such as how many times vape device  10  is used during a given period of time (hour, day, week, etc.), the duration of each use of vape device  10 , how many draws the user takes on vape device  10 , the strength of those draws, the amount of payload consumed during each use of vape device  10 , and other information as described herein. The historical vape device usage information may be stored in a database in association with the payload identifier. In some embodiments, the historical vape device usage information can be used as clinical data for determining whether the user is consuming the right amount of medicine to be vaporized and inhaled and at the right times of day. The information can be used to provide feedback to the user in terms of whether the user should consume medicine more frequently or less frequently throughout the day and/or to increase or decrease the amount of medicine consumed per usage overall or per usage at particular times of the day. In some embodiments, the information collected about the user&#39;s consumption of a  cannabis  liquid or oil payload with vape device  10  can be used to estimate the user&#39;s intoxication or impairment based on the user&#39;s physical characteristics and the amount of  cannabis  liquid or oil payload consumed. This estimation can be relayed to the user as a means to inform the user as to whether the user is too intoxicated or impaired to operate a motor vehicle or to operate tools or machinery, as an example. 
     Second Embodiment of Vape Device 
     Referring to  FIG. 2 , a second embodiment of a vape device is shown generally as reference numeral  100 . In some embodiments, vape device  100  can comprise control assembly  14 , atomizer assembly  79  and mouthpiece assembly  88  operatively coupled together in that order using mechanical connection means  56  to join the subassemblies together. Mechanical connection means  56  can comprise one or more of threaded connection means, magnetic connection means and friction or press-fit connection means, and any of the connection means  15  described above, including  510  threaded connectors. In some embodiments, mouthpiece assembly  88  can comprise a mouthpiece  58  in communication with the outlet of atomizer  20  via conduit  60 , which is typically a hollow tube made of stainless steel, aluminum, or other materials known to those skilled in the art. Mouthpiece assembly  88  can further comprise a payload reservoir  62  that can be filled with a payload  64  that may be liquid or oil. The payload  64  can flow from payload reservoir  62  to inlet  21  of atomizer  20  via one or more valves  68 . In some embodiments, mouthpiece assembly  88  can comprise memory device  28  and an oil gauge  66 , which can be configured to monitor the volume of payload  64  in payload reservoir  62  and relay that information to microcontroller  31 . In this embodiment, mouthpiece assembly  88  can be a consumable element that can be replaced as a complete subassembly once depleted, or simply interchanged with another mouthpiece assembly  88  containing a different payload  64  for consumption, depending on the needs and wants of the user. In some embodiments, oil gauge  66  can simply be a sight glass disposed on mouthpiece assembly  88  to provide a visual indicator to the user as to the amount of payload remaining therein. Atomizer assembly  79  is preferably configured to prevent air-lock and/or clogging with thick, undiluted payloads. It will be understood to those skilled in the art that an air path will extend through atomizer assembly  79  allowing ambient air to flow from an air inlet (not shown) of atomizer  20  and through conduit  60  to mouthpiece  58 . 
     Control assembly  14  of vape device  100  is preferably substantially similar to control assembly  14  of vape device  10 . Atomizer  20  of vape device  100  is preferably substantially similar to atomizer  20  of vape device  10 , and may include alternative means for vaporizing a payload other than a heating element as described above in connection with vape device  10 . It is within the scope of the invention for atomizer assembly  79  and mouthpiece assembly  88  to be formed integrally within a common housing that is releasably connected to control assembly  14 . Further, it is within the scope of the invention for control assembly  14  and atomizer assembly  79  to be formed integrally within a common housing that is releasably connected to mouthpiece assembly  88 . It is also within the scope of the invention for atomizer assembly  79 , mouthpiece assembly  88 , and control assembly  14  to be formed integrally within a common housing. 
     Vape Device Application 
     Referring to  FIG. 3 , one embodiment of a vape device system  102  includes vape device  10  and a personal computing device  72  running application  74  thereon. It is understood that personal computing device  72  includes a processor  94  that runs application  74 , and that references herein to personal computing device  72  include its processor  94 . Vape device  100  may also be operated with personal computing device  72  in the same manner as described below with respect to vape device  10 . 
     As used herein, the term “personal computing device” is defined as including personal computers, laptop computers, personal digital assistants, personal computing tablets (such as those made by Apple® and Samsung®, and by others as well known to those skilled in the art), smart phones (such as those running on iOS® and Android® operating systems, and others as well known to those skilled in the art), smart watches, fitness tracking wristbands, wearable devices, smart glasses, and any other electronic computing device that comprises means for communication (wireless or wired) with other electronic devices, and with a global telecommunications or computing network. 
     In some embodiments, vape device  10  can wirelessly communicate with personal computing device  72  and application  74  via RF communications link  73 . In some embodiments, RF communications link  73  can comprise one or more of Bluetooth™ communications protocol, Wi-Fi™ IEEE 802 communications protocol, Zigbee IEEE 802.15.4-based protocol, and any other RF, short-range, and long-range communications protocol as well known to those skilled in the art. Vape device  10  may also communicate with personal computing device  72  via a wired connection established, for example, between electrical connector  35  of vape device  10  and a communications connector (not shown) of personal computing device  72 . 
     Vape device  10  can preferably communicate with personal computing device  72  and operate in conjunction with application  74  to control and monitor the use of vape device  10 . In some embodiments, application  74  can be configured to acquire specific information on the payload being vaporized (described below) based on the serial number of the cartridge. In some embodiments, application  74  can access an online source of data to acquire this information, which can be done periodically and/or automatically, or manually by the user prompting the application to update the information, or a combination of both processes. This information can then be used to control or meter the dose of vapor inhaled by the user, as described below. 
     In some embodiments, computing device  72  transmits the unique payload identifier to a remote computing device at a central server or in the cloud. The remote computing device may maintain a database of operational settings that are associated with each unique payload identifier and tailored to the particular substance located in the payload reservoir and/or the particular user using the payload reservoir. The remote computing device may then send the operational settings and identification of the specific substance within the payload reservoir back to the computing device  72 . The historical vape device usage information described above may also be transmitted to and maintained by the remote computing device at the central server or in the cloud. 
     In some embodiments, application  74  can present a visual “dashboard”  75  comprising visual information and controls that can be operated by a user. In some embodiments, dashboard  75  can comprise user information window  76  for displaying information regarding the operation of vape device  10  in addition to general information. This general information can include general news as well as information on available updates for vape device  10  or the application  74  from the manufacturer or supplier of the same. 
     In some embodiments, dashboard  75  can comprise a locate button  78  as a means for the user to determine the location of vape device  10  should the user misplace it. By pressing locate button  78 , personal computing device  72  can send a signal wirelessly to vape device  10  to operate an audible signal from an audio speaker or buzzer or other like device disposed thereon to assist the user in finding vape device  10 . In other embodiments, pressing locate button  78  can assist the user to determine his or her geographic location (using geographic location capabilities of personal computing device  72 ) and whether  cannabis  products can be consumed using vape device  10  in that location (e.g., whether there are any governmental regulations, laws, or rules applicable to or enforceable in the geographic area where vape device  10  is located that may subject the user of vape device  10  to criminal or administrative penalties, fines, or enforcement actions). In some embodiments, dashboard  75  can comprise heat swipe button  80  as a means for the user to manually control the heat used to vaporize payload  64 , wherein the signal transmitted by application  74  to vape device  10  to control the heat can be included in the operational settings. In some embodiments, dashboard  75  can comprise lock indicator  82 , unlock indicator  84  and swipe button  86  as a means to enable and disable vape device  10  by the user swiping swipe button  86  right or left, respectively. 
     II. Dose Metering Methods 
     The vape device as described above may use four different methods, independently or in any combination, to measure the portion of the payload that is vaporized during each user inhalation and thereby determine the dose of vaporized payload delivered to the user. The first method tracks the energy used to vaporize the payload portion during user inhalation in order to determine the mass of the vaporized payload; the second method measures the temperature at multiple locations within the air flow chamber during user inhalation to determine the vapor density and by extension the mass of the vaporized payload; the third method measures the intensity of light that is transmitted through the vaporized payload, reflected off the vaporized payload, or transmitted through a light transmitting medium positioned within the vaporized payload, during user inhalation to determine the vapor density and by extension the mass of the vaporized payload; and the fourth method utilizes hot wire anemometers to determine the mass of the vaporized payload that was delivered to the user during each user inhalation and/or to determine the size and density distribution of the droplets in the vaporized payload and use such distribution to calculate the total mass of the vaporized payload that was delivered to the user during each user inhalation. Each of these methods will be described below in connection with the exemplary vape devices shown in  FIGS. 4-15 . 
     It should be understood that the exemplary vape devices shown in  FIGS. 4-15  are illustrated schematically in order to describe the sensors and other components that may be used to implement the various methods. These schematic diagrams and are not intended to illustrate any particular structural configurations for the vape devices, which will vary depending on the type of vape device that implements the disclosed methods. For example, the atomizer of the vape device may be suspended in a conduit and in fluid communication with the payload from a payload reservoir, or, the atomizer of the vape device may be suspended in a portion of the conduit allowing ambient air from the inlet to flow through the atomizer. The conduit may have a cross-section that is circular, rectangular, or any other shape. The various structural configurations for the cartridge, payload reservoir, conduit, etc. will be apparent to those skilled in the art. 
     In some embodiments, the vape device is also configured to determine the aggregated amount of payload that has been vaporized during previous user inhalations. This amount may be subtracted from the total amount of payload prior to any vaporization to determine the remaining amount of payload in the payload reservoir. Also, because there will be some residual payload in the payload reservoir, the vape device may also be configured to determine the portion of the remaining amount of payload in the payload reservoir that is useable for vaporization—e.g., based on characterization data or testing of samples to determine a mean and range of useable payload with a specified measure of accuracy. Further, the vape device may be configured to provide a notice to the user (e.g., via personal computing device  72 ) when the remaining amount of payload in the payload reservoir is below a minimum level so that the user may take appropriate steps to refill the payload reservoir or obtain a replacement cartridge. 
     Energy Usage Method 
     In some embodiments, the vape device is configured to track the energy used to vaporize a portion of the payload during user inhalation in order to determine the mass of vaporized payload that was delivered to the user during each user inhalation. 
     Referring to  FIG. 4 , an example of a vape device that relies on the energy usage method to determine the dose of vaporized payload is shown generally as reference numeral  400 . Vape device  400  includes a control assembly  410  and a cartridge  420  that may be formed in separate housings that are releasably connected to each other via an electromechanical connection  440 . In this embodiment, control assembly  410  is provided as a re-useable component that can be used with multiple disposable cartridges, such as cartridge  420 . In other embodiments, control assembly  410  may be disposable, or, the components of control assembly  410  and cartridge  420  may be provided as a self-contained vape device. 
     Electromechanical connection  440  is configured to provide a mechanical and electrical connection between control assembly  410  and cartridge  420 . For example, electromechanical connection  440  may comprise a female  510  threaded connector on control assembly  410  that releasably engages a male  510  threaded connector on cartridge  420 . Of course, the invention is not limited to the use of  510  threaded connectors and other types of connectors may also be used, as described above. 
     As shown in  FIG. 4 , control assembly  410  includes a power source  412 , a microcontroller  414 , an RF transceiver circuit  416 , and one or more antennas  418 . Also, cartridge  420  includes a payload reservoir  422 , an atomizer  424 , one or more temperature measurement circuits  426  (optional), one or more pressure measurement circuits  428  (optional), and a memory device  430  (optional). Of course, it should be understood that all or a portion of temperature measurement circuits  426  and/or pressure measurement circuits  428  may alternatively be located within control assembly  410 . Most of these components (with the exception of the temperature and pressure measurement circuits) are described above in connection with vape devices  10  and  100 . Of course, it should be understood that control assembly  410  and cartridge  420  may include a number of other components that are not specifically shown in  FIG. 4 , as also described above in connection with vape devices  10  and  100 . 
     With respect to vape device  400 , microcontroller  414  is programmed to control power source  412  (e.g., a battery) so that power source  412  transmits a power signal (e.g., a direct current or pulsed direct current) to atomizer  424  in accordance with desired operational settings. When the heating element of atomizer  424  reaches the vaporization temperature of the payload contained in payload reservoir  422 , a portion of the payload is vaporized to thereby generate a vaporized payload for user inhalation. As described below, if the amount of energy required to vaporize the total mass of the payload in payload reservoir  422  is known (i.e., the total mass of the payload prior to any vaporization), microcontroller  414  is able to interpolate from the amount of energy used in each user inhalation the partial mass of payload that has been vaporized during the user inhalation. 
     For example, consider a payload having a total mass of 0.5 grams (assuming a density of 1 gram/milliliter) that is known to require 1.240 watt-hours of energy to be fully vaporized. If a particular user inhalation were to use 6.179 milliwatt-hours of energy (e.g., 2 amperes of current at 3.7 volts for 3 seconds), this energy usage would comprise approximately 1/200 th  of the energy required for the total payload. Thus, it is possible to estimate that the partial amount of payload that was vaporized during the user inhalation was 0.0025 grams (i.e., 0.5 grams/200). 
     In some embodiments, microcontroller  414  is programmed to determine the dose of payload that is vaporized during each user inhalation by performing the following steps: (1) determining the amount of energy used to vaporize a portion of the payload during each user inhalation; and (2) using the amount of energy to determine the partial mass of the payload that is vaporized during the user inhalation. Each of these steps will be described in greater detail below. 
     It should be understood that the amount of energy used to vaporize a portion of the payload may be associated with the partial mass of the payload using characterization data for the particular payload (e.g., data that has been obtained through testing to correlate the amount of energy to the partial mass). In some embodiments, microcontroller  414  acquires this information from memory device  430 , i.e., the characterization data is stored in memory device  430  by the manufacturer of cartridge  420 . In other embodiments, microcontroller  414  acquires a unique payload identifier from memory device  430  and transmits the unique payload identifier to personal computing device  72  via RF transceiver  416  and antenna(s)  418 . The unique serial number may comprise, for example, a serial number of cartridge  420 . The application  74  running on personal computing device  72  may then acquire the characterization data based on the unique payload identifier. In some embodiments, application  74  can access an online source of data to acquire this information. Of course, the payload identifier stored in memory device  430  need not comprise a unique identifier, in which case cartridges containing the same type and amount of payload could all store the same payload identifier in their respective memory devices. In all of these cases, computing device  72  transmits the acquired information back to microcontroller  414  via RF transceiver  416  and antenna(s)  418 . In yet other embodiments in which the vape device comprises a self-contained vape device, the characterization data may be stored on microcontroller  414  itself. 
     Microcontroller  414  determines the amount of energy used to vaporize a portion of the payload during each user inhalation by determining the amount of power provided to atomizer  424  during the user inhalation, determining the duration of the user inhalation, and then calculating the total amount of energy based on this information (i.e., E=P×t). In some embodiments, microcontroller  414  is programmed to determine the amount of power provided to atomizer  424  by measuring the output voltage of power source  414 , measuring the current delivered to atomizer  424 , and then calculating the power based on this information (i.e., P=V×I). In other embodiments, microcontroller  414  is programmed to determine the amount of power provided to atomizer  424  by measuring the resistance of the path between power source  412  and atomizer  424 , measuring either the output voltage of power source  414  or the current delivered to atomizer  424 , and then calculating the power based on this information (i.e., P=I 2 ×R=V 2 /R). 
     In some embodiments, the step of determining the amount of energy used to vaporize a portion of the payload during each user inhalation may be further refined (optionally) by determining the air flow rate within the air flow chamber, and then adjusting the total amount of energy calculated above to account for the air flow rate and its effect on removing heat from atomizer  424 . The air flow chamber extends between an inlet and an outlet, and atomizer  424  is positioned between the inlet and outlet such that (1) ambient air flows through the air flow chamber from the inlet to atomizer  424  and (2) air mixed with vaporized payload flows through the air flow chamber from atomizer  424  to the outlet (which may be in communication with a mouthpiece). Those skilled in the art will appreciate that increasing the air flow rate will pull more vapor (and by extension heat) away from atomizer  424  thereby causing the control loop to add more energy into the heating element to maintain a constant temperature. Including the effect of the air flow rate using a direct air flow measurement will increase the accuracy of the dose measurement. 
     In some embodiments, microcontroller  414  is programmed to determine the air flow rate within the air flow chamber based on a pressure difference across an orifice positioned anywhere in the sealed path between the inlet and outlet of the air flow chamber and the known cross-sectional area of the orifice. As described below, there are different ways to determine the pressure differential across the orifice using one or more pressure sensors incorporated within pressure measurement circuit(s)  428 . 
     In one embodiment, a first pressure sensor is located on one side of the orifice and a second pressure sensor is located on the opposing side of the orifice. The first pressure sensor is incorporated into a first pressure measurement circuit configured to obtain a plurality of pressure measurements during user inhalation. Similarly, the second pressure sensor is incorporated into a second pressure measurement circuit configured to obtain a plurality of pressure measurements during user inhalation. Thus, the pressure difference across the orifice during user inhalation is based on the pressure measurements obtained by the first and second pressure measurement circuits during user inhalation. 
     In another embodiment, a single pressure sensor is located on one side of the orifice. The pressure sensor is incorporated into a pressure measurement circuit configured to obtain a plurality of pressure measurements before and during user inhalation, e.g., one or more ambient pressure measurements before the draw in which the pressure is equal on either side of the orifice followed by other pressure measurements during the draw in which there is a partial vacuum on the side of the orifice where the pressure sensor is located. Thus, the pressure difference across the orifice during user inhalation is based on the pressure measurements obtained by the pressure measurement circuit before and during user inhalation. 
     In another embodiment, a single pressure sensor is located on one side of the orifice. The pressure sensor is incorporated into a pressure measurement circuit configured to obtain a plurality of pressure measurements during and after user inhalation, e.g., pressure measurements during the draw in which there is a partial vacuum on the side of the orifice where the pressure sensor is located followed by one or more ambient pressure measurements after the draw in which the pressure is equal on either side of the orifice. Thus, the pressure difference across the orifice during user inhalation is based on the pressure measurements obtained by the pressure measurement circuit during and after user inhalation. 
     In yet another embodiment, a single pressure sensor is located on one side of the orifice. The pressure sensor is incorporated into a pressure measurement circuit configured to obtain a plurality of pressure measurements before, during and after user inhalation, e.g., a combination of the above two embodiments, such that the ambient pressure measurements before and after the draw are used and compared to the partial vacuum measurements during the draw. Thus, the pressure difference across the orifice during user inhalation is based on the pressure measurements obtained by the pressure measurement circuit before, during and after user inhalation. 
     In some embodiments, the step of determining the amount of energy used to vaporize a portion of the payload during each user inhalation may be further refined (optionally) by determining the amount of energy used to heat atomizer  424  to the vaporization temperature, and then adjusting the total amount of energy calculated above by subtracting or omitting that portion of the total energy. In order to determine when atomizer  424  has reached the vaporization temperature, a temperature sensor incorporated into temperature measurement circuit  426  may be used to sense the temperature within cartridge  420 . Various examples of temperature sensors that may be used in temperature measurement circuit  426  are described below. 
     In general, the temperature sensor may comprise any type of component capable of sensing the temperature within cartridge  420 . For example, temperature sensor  426  may comprise a thermistor, a thermocouple, a bandgap temperature sensor, an analog temperature sensor, a digital temperature sensor (e.g., temperature sensors with I2C interface compatibility), or any other type of temperature sensor known to those skilled in the art. The thermal path between atomizer  424  and the temperature sensor may be implemented with thermal paste, a ceramic thermal bridge (e.g., the Q-Bridge thermal conductor available from American Technical Ceramics), or air and PCB dielectric. 
     The temperature sensor may also comprise a light sensor configured to detect light emitted from a material within cartridge  420 , wherein the intensity of the emitted light is proportional to the temperature of the material, as is known to those skilled in the art. The light sensor may comprise, for example, a photodiode or phototransistor that detects light emitted by the heating element and/or light emitted by the vaporized payload (which would typically be in the infrared region of 0.7 microns to 20 microns). The light sensor is preferably able to detect the light through different seals or glass so that the light sensor can be isolated from the vaporized payload. 
     The temperature sensor may also comprise a circuit configured to measure the resistance of the heating element and utilize this measurement to determine the temperature within cartridge  420 . As is known in the art, the resistance of the heating element is directly proportional to the resistivity of the material from which the heating element is made (i.e., the resistance is dependent on the resistivity, length, and cross-sectional area of the heating element). The relationship between the resistivity of the heating element and temperature is shown by the following equation (which is a linear approximation for cases in which the temperature variance is not large): 
       ρ=ρ 0 (1+α( T−T   0 ))  (1)
 
     where 
     ρ=resistivity of heating element at temperature T in ohm meters; 
     ρ 0 =resistivity of heating element at temperature T 0  in ohm meters; 
     α=temperature coefficient of resistivity at T 0 ; 
     T=current temperature in ° K; and 
     T 0 =fixed reference temperature (e.g., ambient temperature) in ° K. 
     It can be seen from equation (1) that the resistivity of the heating element increases with an increase in the current temperature of the heating element. Thus, if the resistance of the heating element is known at any given moment, it is possible to calculate the resistivity of the heating element and, using equation (1), calculate the current temperature of the heating element. 
     For example, the following method may be implemented to determine the current temperature of the heating element (and thus the temperature within cartridge  420 ): (a) measure the ambient temperature within cartridge  420  (the heating element will be approximately the same temperature provided it has not been activated recently); (b) periodically measure the resistance of the heating element while the heating element is being powered; and (c) calculate the current temperature of the heating element based on the measured resistance (or determine a change in the resistance of the heating element to provide the temperature increase above the ambient temperature value). Thus, the resistance of the heating element as a function of temperature can be used to provide an accurate assessment of the temperature within cartridge  420  at any given moment. 
     In addition, in some embodiments, the step of determining the amount of energy used to vaporize a portion of the payload during each user inhalation may be further refined (optionally) by adjusting the total amount of energy calculated above to account for one or more operating conditions, such as those listed in Table 1 below: 
     
       
         
           
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Operating Condition 
                 Impact on Energy 
               
               
                   
               
             
            
               
                 starting temperature of 
                 The starting temperature of the vape device&#39;s 
               
               
                 vape device 
                 materials (e.g., the housing, battery, payload 
               
               
                   
                 reservoir, etc.) will impart a baseline 
               
               
                   
                 temperature to the volume of air in the vape 
               
               
                   
                 device. 
               
               
                 starting temperature of 
                 The payload temperature determines the 
               
               
                 payload 
                 starting point from which the payload must be 
               
               
                   
                 heated. The colder the payload, the more 
               
               
                   
                 energy must be supplied to the atomizer before 
               
               
                   
                 the payload will begin to vaporize. 
               
               
                 temperature of ambient 
                 The ambient air drawn into the inlet during an 
               
               
                 air 
                 inhale will bring with it an amount of heat 
               
               
                   
                 energy that will offset the air at the outlet. The 
               
               
                   
                 colder the ambient air, the less it is expected 
               
               
                   
                 that the air at the outlet will increase. The 
               
               
                   
                 warmer the ambient air, the more it is expected 
               
               
                   
                 that the air at the outlet will increase. 
               
               
                 relative humidity of 
                 The ambient relative humidity changes the 
               
               
                 ambient air 
                 specific heat capacity of the ambient air, 
               
               
                   
                 making it require more or less energy to impart 
               
               
                   
                 the same temperature change. 
               
               
                 pressure of ambient air 
                 Ambient pressure is used to determine the flow 
               
               
                   
                 rate of the air through the orifice. The ambient 
               
               
                   
                 pressure occurs on one side of the orifice and 
               
               
                   
                 the inhale pressure occurs on the other side of 
               
               
                   
                 the orifice. It is the difference between these 
               
               
                   
                 two that can be used to determine the flow rate. 
               
               
                 output voltage of power 
                 As the battery voltage changes through normal 
               
               
                 source 
                 use, the maximum amount of power that can be 
               
               
                   
                 put into the atomizer is reduced. 
               
               
                 temperature ramp rate of 
                 This operating condition can be used to 
               
               
                 atomizer 
                 determine the thermal mass in thermal 
               
               
                   
                 communication with the heating element. This 
               
               
                   
                 information can be used to determine how 
               
               
                   
                 much payload is present and available for 
               
               
                   
                 vaporization. 
               
               
                   
               
            
           
         
       
     
     As discussed above, microcontroller  414  uses the amount of energy calculated above to determine the partial mass of the payload that is vaporized during user inhalation. In some embodiments, this step may be further refined (optionally) to determine the mass of each of the components within the payload that are vaporized during user inhalation (assuming that the payload and its constituent components and relative percentages are known). For example, assume that the payload includes known percentages of CBD and THC, wherein CBD vaporizes at 150° C. (i.e., the boiling point of CBD) and THC vaporizes at 178° C. (i.e., the boiling point of THC). Microcontroller  414  can predict the relative amounts of CBD and THC vaporized at temperatures of 140° C., 160° C., 180° C., etc., to provide specific information on the dose of CBD and THC delivered to the user during user inhalation. Further, microcontroller  414  may optionally determine an optimal vaporization temperature for the payload based on the relative percentage and boiling point for each of the components within the payload. 
     Finally, it should be understood that all or a portion of the processing steps performed by microcontroller  414 , as described above, could alternatively be performed by one or more other microcontrollers, such as a secondary microcontroller (not shown) positioned in cartridge  420 . For example, in some embodiments, a secondary microcontroller positioned in cartridge  420  is programmed to determine the amount of energy delivered to atomizer  424  during each user inhalation and then transmit this information to microcontroller  414  over the electrical interface between cartridge  420  and control assembly  410 . In this case, microcontroller  414  would perform all of the other steps described above. In other embodiments, a secondary microcontroller positioned in cartridge  420  is programmed to perform all of the steps described above and then transmit the dose of the vaporized payload to microcontroller  414  over the electrical interface between cartridge  420  and control assembly  410 . In yet other embodiments, personal computing device  72  is programmed to perform a portion of the steps described above, assuming that the appropriate information is passed from the vape device to personal computing device  72 . Further, in some embodiments, a secondary microcontroller positioned in cartridge  420  is configured by microcontroller  414  positioned in control assembly  410  or, alternatively, the secondary microcontroller uses operational settings stored in memory device  430  to determine when to stop atomizer  424  so as to deliver a full dose (wherein the full dose may also be stored in memory device  430 ). Of course, those skilled in the art will appreciate that the steps performed by microcontroller  414  and any secondary microcontroller will vary between different applications. 
     Temperature Measurement Method 
     In some embodiments, the vape device is configured to measure the temperature at multiple locations within the air flow chamber during user inhalation (and optionally before and after user inhalation) to determine the vapor density and by extension the mass of vaporized payload that was delivered to the user during each user inhalation. 
     Referring to  FIG. 5 , an example of a vape device that relies on the temperature measurement method to determine the dose of vaporized payload is shown generally as reference numeral  500 . Vape device  500  includes a housing  502 , which may comprise an internal housing or external housing of vape device  500 . Positioned within housing  502  is an air flow chamber which, in this example, comprises a conduit  512  that extends between an inlet  504  and an outlet  506 . It can be appreciated that the inlet and outlet orifices are defined by conduit  512 . An atomizer  510  is positioned anywhere between inlet  504  and outlet  506 . As described above, atomizer  510  is configured to heat and vaporize the payload contained in a payload reservoir (not shown) so as to output a vaporized payload. During a user inhalation, ambient air flows through conduit  512  from inlet  504  to atomizer  510 , and ambient air mixed with vaporized payload flows through conduit  512  from atomizer  510  to outlet  506 . Outlet  506  may further be in communication with a mouthpiece, as described above. Of course, it should be understood that vape device  500  may include a number of other components that are not specifically shown in  FIG. 5 , including a power source, a microcontroller, and other electronics, as described above in connection with vape devices  10  and  100 . 
     With respect to vape device  500 , the microcontroller is programmed to control the power source (e.g., a battery) so that the power source transmits a power signal (e.g., a direct current or pulsed direct current) to atomizer  510  in accordance with desired operational settings. When the heating element of atomizer  510  reaches the vaporization temperature of the payload contained in the payload reservoir, a portion of the payload is vaporized to thereby generate the vaporized payload for user inhalation. As described below, the vaporized payload transfers a significant amount of heat from atomizer  510  to the air that is flowing through conduit  512  to outlet  506 —significantly more so than air alone. There are key locations in the air path within conduit  512 —i.e., a location between inlet  504  and atomizer  510  and one or more locations between atomizer  510  and outlet  506 —where temperature measurements can provide valuable information. 
     In this example, vape device  500  includes three temperature sensors. Specifically, a first temperature sensor  514  is located within conduit  512  between inlet  504  and atomizer  510 , wherein first temperature sensor  514  is incorporated into a first temperature measurement circuit configured to obtain a plurality of temperature measurements during user inhalation (and optionally before and after user inhalation). Also, a second temperature sensor  516  is located within conduit  512  between atomizer  510  and outlet  506  (relatively close to atomizer  510 ), wherein second temperature sensor  516  is incorporated into a second temperature measurement circuit configured to obtain a plurality of temperature measurements during user inhalation (and optionally before and after user inhalation). In addition, a third temperature sensor  518  is located within conduit  512  between atomizer  510  and outlet  506  (close to outlet  506 ), wherein third temperature sensor  518  is incorporated into a third temperature measurement circuit configured to obtain a plurality of temperature measurements during user inhalation (and optionally before and after user inhalation). 
     Each of temperature sensors  514 ,  516  and  518  may comprise any type of component capable of sensing the temperature at the designated locations, such as a thermistor, a thermocouple, an infrared sensor, a bandgap temperature sensor, an analog temperature sensor, or a digital temperature sensor. Of course, those skilled in the art will understand that other types of temperature sensors may be used in accordance with the present invention. 
     Using the measured temperatures and the relative temperature changes between temperature sensors  514 ,  516  and  518  in conjunction with the air flow rate within conduit  512  (which may be determined using one or more pressure measurement circuits, such as pressure measurement circuit(s)  428  described above in connection with  FIG. 4 ), it is possible to determine the amount of vaporized payload required to transfer the heat energy throughout the air path. Specifically, the vaporized payload has a specific heat capacity and carries heat away from atomizer  510  and towards outlet  506 . As more vapor is created, more heat energy will be transferred downstream. Given a fixed, non-zero air flow rate, the temperature within conduit  512  between atomizer  510  and outlet  506  will be higher than the temperature within conduit  512  between inlet  504  and atomizer  510 . Likewise, for a fixed amount of vapor, there will be a lower temperature rise for higher air flow rates because there is more ambient air mixed with the vaporized payload thereby reducing the amount of heat being transferred within conduit  512  from atomizer  510  to outlet  506 . Thus, through characterization over various operating conditions, an accurate estimate of the vapor density of the vaporized payload can be determined. Using the vapor density and the air flow rate over time, it is possible to determine the mass of payload that was vaporized for user inhalation and by extension the dose that the user received. 
     Thus, in some embodiments, the microcontroller of vape device  500  is programmed to determine the dose of payload that is vaporized during each user inhalation by performing the following steps: (1) acquiring a plurality of temperature measurements obtained at various locations within the air flow chamber during user inhalation (and optionally before and after user inhalation); (2) determining the air flow rate within the air flow chamber during user inhalation; and (3) using the information from steps 1 and 2 to determine the vapor density of the vaporized payload and by extension the partial mass of the payload that is vaporized during user inhalation. 
     In some embodiments, the method may be further refined (optionally) by using a thermistor as part of one or more of the temperature measurement circuits. The thermistor may be biased to a more sensitive operating region by passing current (direct current or pulsed direct current) such that it self-heats the thermistor. By tracking the amount of current increase required to keep the thermistor at the same temperature, an estimate of the air flow rate, vapor density, etc., may be determined using characterization data. 
     In some embodiments, the method may be further refined (optionally) by accounting for the air moisture content and atmospheric pressure within the air flow chamber prior to vaporization, e.g., within conduit  512  between inlet  504  and atomizer  510 . These operating conditions will alter the rate at which the temperature changes throughout the air flow path. 
     Finally, it should be understood that all or a portion of the processing steps performed by the microcontroller of vape device  500 , as described above, could alternatively be performed by one or more other microcontrollers, such as a secondary microcontroller (not shown) positioned in a cartridge of vape device  500  (for embodiments in which vape device  500  comprises a cartridge releasably connected to a control assembly). Various embodiments will be apparent to those skilled in the art. 
     Light Intensity Measurement Methods 
     Various examples of vape devices that utilize different light intensity measurement methods will be described below. In each of these examples, the vape device includes at least one light sensor comprised of a light source and a light detector. The light source may comprise, for example, a light emitting diode (LED), a laser, or an incandescent lamp, although other types of light sources may also be used. The light detector may comprise, for example, a photo-diode, although other types of light detectors may also be used. 
     The characteristics of the light emitted by the light source for detection by the light detector will vary between different applications. The wavelength of the emitted light may fall in the visible or invisible (ultraviolet or infrared) portions of the electromagnetic spectrum. The emitted light may be continuous, or the light may be pulsed, for example, to save power or to take successive light intensity measurements. The pulsing is preferably scaled to reflect the air flow rate. 
     As discussed below, the light source and light detector are incorporated into a light intensity measurement circuit configured to obtain a plurality of light intensity measurements during each user inhalation (and optionally before and after user inhalation) and provide such measurements to the microcontroller of the vape device. Preferably, the characterization data used by the microcontroller to determine the vapor density based on the light intensity measurements will account for the vapor density changing with temperature and air flow rate. 
     In some examples, the light sensor is a reflective sensor in which the light source is configured to emit light that is directed toward the path of the vaporized payload and the light detector is configured to detect the light reflection from the vaporized payload (such as the light sensor incorporated into the vape device shown in  FIG. 6 ). When the vapor density of the vaporized payload increases, the light reflection from the vaporized payload increases. Conversely, when the vapor density of the vaporized payload decreases, the light reflection from the vaporized payload decreases. These properties can be utilized to determine the vapor density of the vaporized payload. 
     With a reflective sensor, the wavelength of the emitted light may be selected so that the light is maximally reflected by the vaporized payload. The intensity of the emitted light is preferably low enough so that the reflected light does not overwhelm the light detector. In some embodiments, the light intensity is ramped over a very short time period (but slow enough that the photo-diode is able to track it) in order to identify the point at which the photo-diode begins to saturate. The photo-diode will saturate earlier if the vaporized payload has a higher vapor density and is more reflective. In some embodiments, the light intensity is dynamically modified based on the measured vapor density of the vaporized payload. 
     In other examples, the light sensor is a transmissive sensor in which the light source is configured to emit light that is directed toward the path of the vaporized payload and the light detector is configured to detect light transmission through the vaporized payload (such as the light sensors incorporated into the vape devices shown in  FIGS. 7-10 ). When the vapor density of the vaporized payload increases, the light transmission through the vaporized payload decreases. Conversely, when the vapor density of the vaporized payload decreases, the light transmission through the vaporized payload increases. These properties can be utilized to determine the vapor density of the vaporized payload. 
     With a transmissive sensor, the wavelength of the emitted light may be selected so that the light is maximally absorbed by the vaporized payload. The intensity of the emitted light is preferably high enough to result in some light reaching the light detector. In some embodiments, the light intensity is ramped over a very short time period (but slow enough that the photo-diode is able to track it) in order to identify the point at which the photo-diode begins to saturate. The photo-diode will saturate earlier if the vaporized payload has a lower vapor density. In some embodiments, the light intensity is dynamically modified based on the measured vapor density of the vaporized payload. 
     In yet other examples, the light source is configured to emit light that is directed toward a light transmitting medium positioned within the path of the vaporized payload and the light detector is configured to detect light transmitted through the medium (such as the light sensors incorporated into the vape devices shown in  FIGS. 11-13 ). The light transmitting medium is made of glass, plastic or another material with an index of refraction that is sufficiently similar to that of the payload and sufficiently different from that of air. 
     When the surface of the light transmitting medium is surrounded entirely by air prior to any use of the vape device, most of the light emitted by the light source will travel through the medium to the light detector. Notably, when the light impacts the medium/air boundary at an angle, the light will totally reflect back into the medium (i.e., total internal reflection) due to the differences between the index of refraction of the medium and the index of refraction of air. Thus, the light detected by the light detector will have substantially the same intensity as the light emitted by the light source. 
     However, when vaporized payload, e.g., an oil droplet, is deposited on the surface of the light transmitting medium during use of the vape device, some of the light traveling through the medium will impact the medium/payload boundary at an angle and escape the medium into the deposited payload due to the similarities between the index of refraction of the medium and the index of refraction of the payload. Thus, the level of attenuation of the light received by the light detector will be dependent on the total amount of payload deposited on the surface of the medium. 
     It should be understood that the light transmission through the medium will decrease as the medium becomes increasingly fouled (coated) with droplets from the vaporized payload over the lifetime of the medium—i.e., there will be residual payload deposited on the surface of the medium after each user inhalation. Light intensity measurements are preferably obtained before, during, and after each user inhalation, and the rate of decrease of light transmission through the medium indicates the amount of vaporized payload that has passed the medium during that user inhalation. These properties can be utilized to determine the vapor density of the vaporized payload. Because the light transmitting medium has a limited lifetime, it is preferably placed in a replaceable cartridge portion of the vape device. 
     With this type of light sensor, the intensity of the emitted light is preferably increased over the lifetime of the light transmitting medium. When the medium is clean, very little of the emitted light will escape the medium due to total internal reflection at the medium/air boundary. As such, the emitted light can have a low intensity and still be detectable at the light detector. However, as droplets from the vaporized payload successively collect on the outside surface of the light transmitting medium throughout the lifetime of the medium, more light will escape the medium at the medium/payload boundary. As such, the emitted light must have a higher intensity to be detectable at the light detector. 
     The material of the light transmitting medium may be selected to obtain a desired index of refraction and associated effect. Those skilled in the art will appreciate that the critical angle is the smallest angle of incidence that yields total internal reflection through a light transmitting medium, as shown by the following equation: 
       θ c =arc sin( n   2   /n   1 )  (2)
 
     where 
     θ c =critical angle in degrees; 
     n 1 =index of refraction of light transmitting medium; and 
     n 2 =index of refraction of material adjacent to light transmitting medium (e.g., the droplets from the vaporized payload). 
     The closer the indexes of refraction are between the light transmitting medium and the droplets from the vaporized payload, the more likely it will be that the light escapes the medium into one of the droplets. In some embodiments, the index of refraction of the light transmitting medium is selected so as to be substantially the same as the index of refraction of the vaporized payload so as to maximize the amount of escaped light. In other embodiments, the index of refraction of the light transmitting medium is selected so as to be slightly different than the index of refraction of the vaporized payload so as to limit the amount of escaped light, which may be beneficial in cases where it is desired to limit the amount of attenuation at the light detector. In other embodiments, the payload is modified via the use of additive(s) so as to obtain a desired index of refraction, although this approach is not preferred insofar as any such additive(s) may be inhaled by the user—i.e, it is preferred to modify the index of refraction of the light transmitting medium. 
     Of course, other vape devices may include any combination of the foregoing types of light sensors. For example, a vape device may include both a reflective sensor and a transmissive sensor that are used either simultaneously or sequentially to switch between the reflective and transmissive modes (depending on which mode provides better dynamic range). 
     Referring to  FIG. 6 , a first example of a vape device that relies on a light intensity measurement method to determine the dose of vaporized payload is shown generally as reference numeral  600 . Vape device  600  includes a housing  602 , which may comprise an internal housing or external housing of vape device  600 . Positioned within housing  602  is an air flow chamber which, in this example, comprises a conduit  612  that extends between an inlet  604  and an outlet  606 . It can be appreciated that the inlet and outlet orifices are defined by conduit  612 . An atomizer  610  is positioned anywhere between inlet  604  and outlet  606 . As described above, atomizer  610  is configured to heat and vaporize the payload contained in a payload reservoir (not shown) so as to output a vaporized payload. During a user inhalation, ambient air flows through conduit  612  from inlet  604  to atomizer  610 , and ambient air mixed with vaporized payload flows through conduit  612  from atomizer  610  to outlet  606 . Outlet  606  may further be in communication with a mouthpiece, as described above. Of course, it should be understood that vape device  600  may include a number of other components that are not specifically shown in  FIG. 6 , including a power source, a microcontroller, and other electronics, as described above in connection with vape devices  10  and  100 . 
     With respect to vape device  600 , the microcontroller is programmed to control the power source (e.g., a battery) so that the power source transmits a power signal (e.g., a direct current or pulsed direct current) to atomizer  610  in accordance with desired operational settings. When the heating element of atomizer  610  reaches the vaporization temperature of the payload contained in the payload reservoir, a portion of the payload is vaporized to thereby generate the vaporized payload for user inhalation. As described above, the microcontroller is programmed to determine the dose of vaporized payload based on a plurality of light intensity measurements obtained during user inhalation (and optionally before and after user inhalation), wherein the light intensity measurements are associated with light reflected from the vaporized payload when the vaporized payload passes through conduit  612  from atomizer  610  to outlet  606 . 
     As shown in  FIG. 6 , vape device  600  includes a light source  614  and a light detector  616  positioned side-by-side within housing  602  outside of conduit  612  between atomizer  610  and outlet  606 . In this example, conduit  612  includes a transparent section  618  formed on its sidewall that is located adjacent to light source  614  and light detector  616 . Transparent section  618  may be made of glass or any other transparent material known to those skilled in the art. As used herein, the term “transparent” generally means transparency for light and includes both clear transparency as well as translucency. Generally, a material is considered transparent if at least about 50%, preferably about 60%, more preferably about 70%, more preferably about 80% and still more preferably about 90% of the light illuminating the material can pass through the material. 
     The light path between light source  614  and light detector  616  is indicated by dashed lines in  FIG. 6 . As can be seen, light source  614  is configured to emit light that passes through transparent section  618  and into conduit  612 , whereby some of the light reflects off the vaporized payload within conduit  612  and passes back through transparent section  618  to light detector  616  (noting that some of the emitted light will not be reflected back to light detector  616 ). Light detector  616  is then configured to generate a signal representing the intensity of the reflected light. As discussed above, light source  614  and light detector  616  are incorporated into a light intensity measurement circuit configured to obtain a plurality of light intensity measurements during each user inhalation (and optionally before and after user inhalation) and provide such measurements to the microcontroller of vape device  600 . 
     It should be understood that various modifications could be made to vape device  600  within the scope of the present invention. For example, in some embodiments, light source  614  and light detector  616  are positioned within conduit  612  (e.g., attached on a sidewall of conduit  612 ) so that the vaporized payload can flow past light source  614  and light detector  616 , provided that appropriate steps are taken to protect the integrity of the components within conduit  612 . In this case, transparent section  618  of conduit  612  would not be required. Of course, other modifications will be apparent to those skilled in the art. 
     Referring to  FIG. 7 , a second example of a vape device that relies on a light intensity measurement method to determine the dose of vaporized payload is shown generally as reference numeral  700 . Vape device  700  includes a housing  702 , which may comprise an internal housing or external housing of vape device  700 . Positioned within housing  702  is an air flow chamber which, in this example, comprises a conduit  712  that extends between an inlet  704  and an outlet  706 . It can be appreciated that the inlet and outlet orifices are defined by conduit  712 . An atomizer  710  is positioned anywhere between inlet  704  and outlet  706 . As described above, atomizer  710  is configured to heat and vaporize the payload contained in a payload reservoir (not shown) so as to output a vaporized payload. During a user inhalation, ambient air flows through conduit  712  from inlet  704  to atomizer  710 , and ambient air mixed with vaporized payload flows through conduit  712  from atomizer  710  to outlet  706 . Outlet  706  may further be in communication with a mouthpiece, as described above. Of course, it should be understood that vape device  700  may include a number of other components that are not specifically shown in  FIG. 7 , including a power source, a microcontroller, and other electronics, as described above in connection with vape devices  10  and  100 . 
     With respect to vape device  700 , the microcontroller is programmed to control the power source (e.g., a battery) so that the power source transmits a power signal (e.g., a direct current or pulsed direct current) to atomizer  710  in accordance with desired operational settings. When the heating element of atomizer  710  reaches the vaporization temperature of the payload contained in the payload reservoir, a portion of the payload is vaporized to thereby generate the vaporized payload for user inhalation. As described above, the microcontroller is programmed to determine the dose of vaporized payload based on a plurality of light intensity measurements obtained during user inhalation (and optionally before and after user inhalation), wherein the light intensity measurements are associated with light transmitted through the vaporized payload when the vaporized payload passes through conduit  712  from atomizer  710  to outlet  706 . 
     As shown in  FIG. 7 , vape device  700  includes a light source  714  and a light detector  716  positioned within housing  702  outside of conduit  712  between atomizer  710  and outlet  706 , wherein light source  714  is positioned on a first side of conduit  712  and light detector  716  is positioned on a second opposing side of conduit  712 . In this example, conduit  712  includes a first transparent section  718  formed on its sidewall adjacent light source  714  and a second transparent section  720  formed on its sidewall adjacent light detector  716 . Transparent sections  718  and  720  may be made of glass or any other transparent material known to those skilled in the art. 
     The light path between light source  714  and light detector  716  is indicated by dashed lines in  FIG. 7 . As can be seen, light source  714  is configured to emit light that passes through transparent section  718  and into conduit  712 , whereby the light travels through the vaporized payload within conduit  712  (noting that some of the light is absorbed by the vaporized payload) and passes through transparent section  720  to light detector  716 . Light detector  716  is then configured to generate a signal representing the intensity of the light that is received at light detector  716 . As discussed above, light source  714  and light detector  716  are incorporated into a light intensity measurement circuit configured to obtain a plurality of light intensity measurements during each user inhalation (and optionally before and after user inhalation) and provide such measurements to the microcontroller of vape device  700 . 
     It should be understood that various modifications could be made to vape device  700  within the scope of the present invention. For example, in some embodiments, light source  714  and light detector  716  are positioned within conduit  712  (e.g., attached on opposing sidewalls of conduit  712 ) so that the vaporized payload can flow past light source  714  and light detector  716 , provided that appropriate steps are taken to protect the integrity of the components within conduit  712 . In this case, transparent sections  718  and  720  of conduit  712  would not be required. Of course, other modifications will be apparent to those skilled in the art. 
     Referring to  FIG. 8 , a third example of a vape device that relies on a light intensity measurement method to determine the dose of vaporized payload is shown generally as reference numeral  800 . In this example, vape device  800  includes a cartridge  808  and a control assembly  814  formed in separate housings  802  and  832 , respectively, which are releasably connected to each other via an electromechanical connection, as described above. Housings  802  and  832  may comprise an internal housing or external housing of cartridge  808  and control assembly  814 , respectively. Positioned within housings  802  and  832  is an air flow chamber which, in this example, comprises a conduit  812  that extends between an inlet  804  within control assembly  814  and an outlet  806  within cartridge  808 . It can be appreciated that the inlet and outlet orifices are defined by conduit  812 . An atomizer  810  is positioned anywhere between inlet  804  and outlet  806  within cartridge  808 . As described above, atomizer  810  is configured to heat and vaporize the payload contained in a payload reservoir (not shown) so as to output a vaporized payload. During a user inhalation, ambient air flows through conduit  812  from inlet  804  to atomizer  810 , and ambient air mixed with vaporized payload flows through conduit  812  from atomizer  810  to outlet  806 . Outlet  806  may further be in communication with a mouthpiece, as described above. Of course, it should be understood that vape device  800  may include a number of other components that are not specifically shown in  FIG. 8 , including a power source, a microcontroller, and other electronics positioned in control assembly  814 , as described above in connection with vape devices  10  and  100 . It should also be understood that conduit  812  may be positioned entirely within cartridge  808 , in which case conduit  812  would not extend through control assembly  814  as shown. 
     With respect to vape device  800 , the microcontroller is programmed to control the power source (e.g., a battery) so that the power source transmits a power signal (e.g., a direct current or pulsed direct current) over the electromechanical connection to atomizer  810  in accordance with desired operational settings. When the heating element of atomizer  810  reaches the vaporization temperature of the payload contained in the payload reservoir, a portion of the payload is vaporized to thereby generate the vaporized payload for user inhalation. As described above, the microcontroller is programmed to determine the dose of vaporized payload based on a plurality of light intensity measurements obtained during user inhalation (and optionally before and after user inhalation), wherein the light intensity measurements are associated with light transmitted through the vaporized payload when the vaporized payload passes through conduit  812  from atomizer  810  to outlet  806 . 
     As shown in  FIG. 8 , vape device  800  includes a light source  816  and a light detector  818  positioned within housing  832  of control assembly  814  outside of conduit  812 , wherein light source  816  is positioned on a first side of conduit  812  and light detector  818  is positioned on a second opposing side of conduit  812 . Also, the interface between control assembly  814  and cartridge  808  includes a first transparent window  820  located adjacent light source  816  and a second transparent window  822  located adjacent light detector  818 . In addition, a first reflective surface  824  and a second reflective surface  826  are located within housing  802  of cartridge  808 . As can be seen, first reflective surface  824  and first transparent window  820  are positioned to align with light source  816 , and second reflective surface  826  and second transparent window  822  are positioned to align with light detector  818 . Further, conduit  812  includes a first transparent section  828  formed on its sidewall adjacent first reflective surface  824  and a second transparent section  830  formed on its sidewall adjacent second reflective surface  826 . Transparent sections  828  and  830  may be made of glass or any other transparent material known to those skilled in the art. 
     The light path between light source  816  and light detector  818  is indicated by dashed lines in  FIG. 8 . As can be seen, light source  816  is configured to emit light that passes through first transparent window  820  to first reflective surface  824 , whereby the light is reflected and redirected though first transparent section  828  and into conduit  812 . The light then travels through the vaporized payload within conduit  812  (noting that some of the light is absorbed by the vaporized payload) and passes through second transparent section  830  to second reflective surface  826 , whereby the light is reflected and redirected through second transparent window  822  to light detector  818 . Light detector  818  is then configured to generate a signal representing the intensity of the light that is received at light detector  818 . As discussed above, light source  816  and light detector  818  are incorporated into a light intensity measurement circuit configured to obtain a plurality of light intensity measurements during each user inhalation (and optionally before and after user inhalation) and provide such measurements to the microcontroller of vape device  800 . 
     Referring to  FIG. 9 , a fourth example of a vape device that relies on a light intensity measurement method to determine the dose of vaporized payload is shown generally as reference numeral  900 . In this example, vape device  900  includes a cartridge  908  and a control assembly  914  formed in separate housings  902  and  928 , respectively, which are releasably connected to each other via an electromechanical connection, as described above. Housings  902  and  928  may comprise an internal housing or external housing of cartridge  908  and control assembly  914 , respectively. Positioned within housings  902  and  928  is an air flow chamber which, in this example, comprises a conduit  912  that extends between an inlet  904  within control assembly  914  and an outlet  906  within cartridge  908 . It can be appreciated that the inlet and outlet orifices are defined by conduit  912 . An atomizer  910  is positioned between inlet  904  and outlet  906  within cartridge  908 . As described above, atomizer  910  is configured to heat and vaporize the payload contained in a payload reservoir (not shown) so as to output a vaporized payload. During a user inhalation, ambient air flows through conduit  912  from inlet  904  to atomizer  910 , and ambient air mixed with vaporized payload flows through conduit  912  from atomizer  910  to outlet  906 . Outlet  906  may further be in communication with a mouthpiece, as described above. Of course, it should be understood that vape device  900  may include a number of other components that are not specifically shown in  FIG. 9 , including a power source, a microcontroller, and other electronics positioned in control assembly  914 , as described above in connection with vape devices  10  and  100 . It should also be understood that conduit  912  may be positioned entirely within cartridge  908 , in which case conduit  912  would not extend through control assembly  914  as shown. 
     With respect to vape device  900 , the microcontroller is programmed to control the power source (e.g., a battery) so that the power source transmits a power signal (e.g., a direct current or pulsed direct current) to atomizer  910  in accordance with desired operational settings. When the heating element of atomizer  910  reaches the vaporization temperature of the payload contained in the payload reservoir, a portion of the payload is vaporized to thereby generate the vaporized payload for user inhalation. As described above, the microcontroller is programmed to determine the dose of vaporized payload based on a plurality of light intensity measurements obtained during user inhalation (and optionally before and after user inhalation), wherein the light intensity measurements are associated with light transmitted through the vaporized payload when the vaporized payload passes through conduit  912  from atomizer  910  to outlet  906 . 
     As shown in  FIG. 9 , vape device  900  includes a light source  916  and a light detector  918  positioned in close proximity to each other within housing  928  of control assembly  914  outside of conduit  912 . Also, the interface between control assembly  914  and cartridge  908  includes a transparent window  920  located adjacent light source  916  and light detector  918 . In addition, a reflective surface  922  is located within housing  902  of cartridge  908 . As can be seen, reflective surface  922  and transparent window  920  are positioned to align with light source  916  and light detector  918 . Further, conduit  912  includes a transparent section  924  formed on its sidewall adjacent reflective surface  922  and a reflective section  926  formed on an opposing sidewall. Transparent section  924  may be made of glass or any other transparent material known to those skilled in the art. Reflective section  926  may be made of polished stainless steel or any other reflective material known to those skilled in the art. If the section of conduit  912  opposite transparent section  924  is sufficiently reflective (e.g., if conduit  912  is made of stainless steel), then a separate reflective section  926  would not be required and that section of conduit  912  would serve as the reflective section. 
     The light path between light source  916  and light detector  918  is indicated by dashed lines in  FIG. 9 . As can be seen, light source  916  is configured to emit light that passes through transparent window  920  to reflective surface  922 , whereby the light is reflected and redirected though transparent section  924  and into conduit  912 . The light then travels through the vaporized payload to reflective section  926 , whereby the light is reflected and redirected back through the vaporized payload (noting that some of the light is absorbed by the vaporized payload). The light then passes through transparent section  924  to reflective surface  922 , whereby the light is reflected and redirected through transparent window  904  to light detector  918 . Light detector  918  is then configured to generate a signal representing the intensity of the light that is received at light detector  918 . As discussed above, light source  916  and light detector  918  are incorporated into a light intensity measurement circuit configured to obtain a plurality of light intensity measurements during each user inhalation (and optionally before and after user inhalation) and provide such measurements to the microcontroller of vape device  900 . 
     Referring to  FIG. 10 , a fifth example of a vape device that relies on a light intensity measurement method to determine the dose of vaporized payload is shown generally as reference numeral  1000 . In this example, vape device  1000  includes a cartridge  1008  and a control assembly  1014  formed in separate housings  1002  and  1028 , respectively, which are releasably connected to each other via an electromechanical connection, as described above. Housings  1002  and  1028  may comprise an internal housing or external housing of cartridge  1008  and control assembly  1014 , respectively. Positioned within housings  1002  and  1028  is an air flow chamber which, in this example, comprises a conduit  1012  that extends between an inlet  1004  within control assembly  1014  and an outlet  1006  within cartridge  1008 . It can be appreciated that the inlet and outlet orifices are defined by conduit  1012 . An atomizer  1010  is positioned anywhere between inlet  1004  and outlet  1006  within cartridge  1008 . As described above, atomizer  1010  is configured to heat and vaporize the payload contained in a payload reservoir (not shown) so as to output a vaporized payload. During a user inhalation, ambient air flows through conduit  1012  from inlet  1004  to atomizer  1010 , and ambient air mixed with vaporized payload flows through conduit  1012  from atomizer  1010  to outlet  1006 . Outlet  1006  may further be in communication with a mouthpiece, as described above. Of course, it should be understood that vape device  1000  may include a number of other components that are not specifically shown in  FIG. 10 , including a power source, a microcontroller, and other electronics positioned in control assembly  1014 , as described above in connection with vape devices  10  and  100 . It should also be understood that conduit  1012  may be positioned entirely within cartridge  1008 , in which case conduit  1012  would not extend through control assembly  1014  as shown. 
     With respect to vape device  1000 , the microcontroller is programmed to control the power source (e.g., a battery) so that the power source transmits a power signal (e.g., a direct current or pulsed direct current) to atomizer  1010  in accordance with desired operational settings. When the heating element of atomizer  1010  reaches the vaporization temperature of the payload contained in the payload reservoir, a portion of the payload is vaporized to thereby generate the vaporized payload for user inhalation. As described above, the microcontroller is programmed to determine the dose of vaporized payload based on a plurality of light intensity measurements obtained during user inhalation (and optionally before and after user inhalation), wherein the light intensity measurements are associated with light transmitted through the vaporized payload when the vaporized payload passes through conduit  1012  from atomizer  1010  to outlet  1006 . 
     As shown in  FIG. 10 , vape device  1000  includes a light source  1016  positioned within housing  1002  of cartridge  1008  outside of conduit  1012  and a light detector  1018  positioned within housing  1028  of control assembly  1014  outside of conduit  1012 . Also, the interface between control assembly  1014  and cartridge  1008  includes a transparent window  1020  located adjacent light detector  1018 . In addition, a reflective surface  1022  is located within housing  1002  of cartridge  1008  outside of conduit  1012 . As can be seen, reflective surface  1022  and transparent window  1020  are positioned to align with light detector  1018 . Further, conduit  1012  includes a first transparent section  1024  formed on its sidewall adjacent reflective surface  1022  and a second transparent section  1026  formed on an opposing sidewall. Transparent sections  1024  and  1026  may be made of glass or any other transparent material known to those skilled in the art. 
     The light path between light source  1016  and light detector  1018  is indicated by dashed lines in  FIG. 10 . As can be seen, light source  1016  is configured to emit light that passes through second transparent section  1026  and into conduit  1012 . The light travels through the vaporized payload within conduit  1012  (noting that some of the light is absorbed by the vaporized payload) and passes through first transparent section  1024  to reflective surface  1022 , whereby the light is reflected and redirected though transparent window  1020  to light detector  1018 . Light detector  1018  is then configured to generate a signal representing the intensity of the light that is received at light detector  1018 . As discussed above, light source  1016  and light detector  1018  are incorporated into a light intensity measurement circuit configured to obtain a plurality of light intensity measurements during each user inhalation (and optionally before and after user inhalation) and provide such measurements to the microcontroller of vape device  1000 . 
     Referring to  FIG. 11A , a sixth example of a vape device that relies on a light intensity measurement method to determine the dose of vaporized payload is shown generally as reference numeral  1100 . Vape device  1100  includes a housing  1102 , which may comprise an internal housing or external housing of vape device  1100 . Positioned within housing  1102  is an air flow chamber which, in this example, comprises a conduit  1112  that extends between an inlet  1104  and an outlet  1106 . It can be appreciated that the inlet and outlet orifices are defined by conduit  1112 . An atomizer  1110  is positioned anywhere between inlet  1104  and outlet  1106 . As described above, atomizer  1110  is configured to heat and vaporize the payload contained in a payload reservoir (not shown) so as to output a vaporized payload. During a user inhalation, ambient air flows through conduit  1112  from inlet  1104  to atomizer  1110 , and ambient air mixed with vaporized payload flows through conduit  1112  from atomizer  1110  to outlet  1106 . Outlet  1106  may further be in communication with a mouthpiece, as described above. Of course, it should be understood that vape device  1100  may include a number of other components that are not specifically shown in  FIG. 11A , including a power source, a microcontroller, and other electronics, as described above in connection with vape devices  10  and  100 . 
     With respect to vape device  1100 , the microcontroller is programmed to control the power source (e.g., a battery) so that the power source transmits a power signal (e.g., a direct current or pulsed direct current) to atomizer  1110  in accordance with desired operational settings. When the heating element of atomizer  1110  reaches the vaporization temperature of the payload contained in the payload reservoir, a portion of the payload is vaporized to thereby generate the vaporized payload for user inhalation. As described above, the microcontroller is programmed to determine the dose of vaporized payload based on a plurality of light intensity measurements obtained before, during, and after user inhalation, wherein the light intensity measurements in this example are associated with light transmitted through a light transmitting medium positioned parallel to the path of the vaporized payload within conduit  1112 , as described below. 
     As shown in  FIG. 11A , vape device  1100  includes a light source  1114  and a light detector  1116  spaced apart from each other within housing  1102  outside of conduit  1112  between atomizer  1110  and outlet  1106 . Also, vape device  1100  includes one or more fibers made of glass, plastic, or another material with an index of refraction that is sufficiently similar to that of the payload and sufficiently different from that of air, as discussed above, which will be referred to herein as a “glass fiber  1118 ” for ease of reference. In this example, glass fiber  1118  is positioned substantially inside of conduit  1118  and extends generally parallel to the direction of the airflow. One end  1118   a  of glass fiber  1118  extends through an opening in the sidewall of conduit  1112  so as to be positioned outside of conduit  1112  adjacent light source  1114 . The other end  1118   b  of glass fiber  1118  penetrates through another opening in the sidewall of conduit  1112  so as to be positioned outside of conduit  1112  adjacent light detector  1116 . Any suitable sealant may be used to seal the openings in conduit  1112  so as to prevent the leakage of vaporized payload therethrough. 
     The light path between light source  1114  and light detector  1116  through glass fiber  1118  can be understood with reference to the simplified diagrams shown in  FIGS. 11B and 11C . 
       FIG. 11B  shows the surface of glass fiber  1118  surrounded entirely by air, i.e., prior to any use of vape device  1100 . The light emitted by light source  1114  travels through glass fiber  1118  to light detector  1116  in a light path indicated by the dashed lines in  FIG. 11B . As can be seen, when the light impacts each glass/air boundary at an angle, the light totally reflects back into glass fiber  1118  (i.e., total internal reflection) due to the differences between their respective indexes of refraction. Thus, the light detected by light detector  1116  has substantially the same intensity as the light emitted by light source  1114 . 
       FIG. 11C  shows the surface of glass fiber  1118  with vaporized payload (an oil droplet in this example) deposited on a portion of the surface. The light emitted by light source  1114  travels through glass fiber  1118  to light detector  1116  in a light path indicated by the dashed lines in  FIG. 11C . As can be seen, when the light impacts the glass/oil boundary at an angle, the light will escape glass fiber  1118  and enter the oil, and some of the light may further escape the oil into the air. However, when the light impacts the glass/air boundary at an angle (i.e., in areas where there are no oil droplets on the surface), the light reflects back into glass fiber  1118 . Thus, the level of attenuation of the light received by light detector  1116  will be dependent on the amount of oil deposited on the surface of glass fiber  1118 . 
     It can be appreciated that light detector  1116  is configured to generate a signal representing the intensity of the received light. As discussed above, light source  1114  and light detector  1116  are incorporated into a light intensity measurement circuit configured to obtain a plurality of light intensity measurements before, during, and after each user inhalation and provide such measurements to the microcontroller of vape device  1100 . 
     It should be understood that various modifications could be made to vape device  1100  within the scope of the present invention. For example, in some embodiments, glass fiber  1118  is positioned entirely inside of conduit  1112 . In this case, a first transparent section is formed on the sidewall of conduit  1112  adjacent light source  1114  to provide a light path between glass fiber  1118  and light source  1114  and, similarly, a second transparent section is formed on the sidewall of conduit  1112  adjacent light detector  1116  to provide a light path between glass fiber  1118  and light detector  1116 . The transparent sections may be made of glass or any other transparent material known to those skilled in the art. In this case, conduit  1112  would not need openings for the ends of glass fiber  1118 . In yet other embodiments, glass fiber  1118  is replaced with another material having an index of refraction similar to that of the vaporized payload, as discussed above. Of course, other modifications will be apparent to those skilled in the art. 
     Referring to  FIG. 12 , a seventh example of a vape device that relies on a light intensity measurement method to determine the dose of vaporized payload is shown generally as reference numeral  1200 . Vape device  1200  includes a housing  1202 , which may comprise an internal housing or external housing of vape device  1200 . Positioned within housing  1202  is an air flow chamber which, in this example, comprises a conduit  1212  that extends between an inlet  1204  and an outlet  1206 . It can be appreciated that the inlet and outlet orifices are defined by conduit  1212 . An atomizer  1210  is positioned anywhere between inlet  1204  and outlet  1206 . As described above, atomizer  1210  is configured to heat and vaporize the payload contained in a payload reservoir (not shown) so as to output a vaporized payload. During a user inhalation, ambient air flows through conduit  1212  from inlet  1204  to atomizer  1210 , and ambient air mixed with vaporized payload flows through conduit  1212  from atomizer  1210  to outlet  1206 . Outlet  1206  may further be in communication with a mouthpiece, as described above. Of course, it should be understood that vape device  1200  may include a number of other components that are not specifically shown in  FIG. 12 , including a power source, a microcontroller, and other electronics, as described above in connection with vape devices  10  and  100 . 
     With respect to vape device  1200 , the microcontroller is programmed to control the power source (e.g., a battery) so that the power source transmits a power signal (e.g., a direct current or pulsed direct current) to atomizer  1210  in accordance with desired operational settings. When the heating element of atomizer  1210  reaches the vaporization temperature of the payload contained in the payload reservoir, a portion of the payload is vaporized to thereby generate the vaporized payload for user inhalation. As described above, the microcontroller is programmed to determine the dose of vaporized payload based on a plurality of light intensity measurements obtained before, during, and after user inhalation, wherein the light intensity measurements in this example are associated with light transmitted through a light transmitting medium positioned perpendicular to the path of the vaporized payload within conduit  1212 , as described below. 
     As shown in  FIG. 12 , vape device  1200  includes a light source  1214  and a light detector  1216  positioned within housing  1202  outside of conduit  1212  between atomizer  1210  and outlet  1206 , wherein light source  1214  is positioned on a first side of conduit  1212  and light detector  1216  is positioned on a second opposing side of conduit  1212 . Also, vape device  1200  includes one or more fibers made of glass, plastic, or another material with an index of refraction that is sufficiently similar to that of the payload and sufficiently different from that of air, as discussed above, which will be referred to herein as a “glass fiber  1218 ” for ease of reference. Glass fiber  1218  is positioned substantially inside of conduit  1212  and extends generally perpendicular to the direction of the airflow. One end  1218   a  of glass fiber  1218  extends through an opening in the sidewall of conduit  1212  so as to be positioned outside of conduit  1212  adjacent light source  1214 . The other end  1218   b  of glass fiber  1218  penetrates through another opening in the sidewall of conduit  1212  so as to be positioned outside of conduit  1212  adjacent light detector  1216 . Any suitable sealant may be used to seal the openings in conduit  1212  so as to prevent the leakage of vaporized payload therethrough. 
     The light path between light source  1214  and light detector  1216  through glass fiber  1218  can be understood from the description of  FIGS. 11B and 11C  above, wherein light detector  1216  is configured to generate a signal representing the intensity of the received light. As discussed above, light source  1214  and light detector  1216  are incorporated into a light intensity measurement circuit configured to obtain a plurality of light intensity measurements before, during, and after each user inhalation and provide such measurements to the microcontroller of vape device  1200 . 
     It should be understood that various modifications could be made to vape device  1200  within the scope of the present invention. For example, in some embodiments, glass fiber  1218  is positioned entirely inside of conduit  1212 . In this case, a first transparent section is formed on the sidewall of conduit  1212  adjacent light source  1214  to provide a light path between glass fiber  1218  and light source  1214  and, similarly, a second transparent section is formed on the sidewall of conduit  1212  adjacent light detector  1216  to provide a light path between glass fiber  1218  and light detector  1216 . The transparent sections may be made of glass or any other transparent material known to those skilled in the art. In this case, conduit  1212  would not need openings for the ends of glass fiber  1218 . In yet other embodiments, glass fiber  1218  is replaced with another material having an index of refraction similar to that of the vaporized payload, as discussed above. Of course, other modifications will be apparent to those skilled in the art. 
     Referring to  FIG. 13 , an eighth example of a vape device that relies on a light intensity measurement method to determine the dose of vaporized payload is shown generally as reference numeral  1300 . Vape device  1300  includes a housing  1302 , which may comprise an internal housing or external housing of vape device  1300 . Positioned within housing  1302  is an air flow chamber which, in this example, comprises a conduit  1312  that extends between an inlet  1304  and an outlet  1306 . It can be appreciated that the inlet and outlet orifices are defined by conduit  1312 . An atomizer  1310  is positioned anywhere between inlet  1304  and outlet  1306 . As described above, atomizer  1310  is configured to heat and vaporize the payload contained in a payload reservoir (not shown) so as to output a vaporized payload. During a user inhalation, ambient air flows through conduit  1312  from inlet  1304  to atomizer  1310 , and ambient air mixed with vaporized payload flows through conduit  1312  from atomizer  1310  to outlet  1306 . Outlet  1306  may further be in communication with a mouthpiece, as described above. Of course, it should be understood that vape device  1300  may include a number of other components that are not specifically shown in  FIG. 13 , including a power source, a microcontroller, and other electronics, as described above in connection with vape devices  10  and  100 . 
     With respect to vape device  1300 , the microcontroller is programmed to control the power source (e.g., a battery) so that the power source transmits a power signal (e.g., a direct current or pulsed direct current) to atomizer  1310  in accordance with desired operational settings. When the heating element of atomizer  1310  reaches the vaporization temperature of the payload contained in the payload reservoir, a portion of the payload is vaporized to thereby generate the vaporized payload for user inhalation. As described above, the microcontroller is programmed to determine the dose of vaporized payload based on a plurality of light intensity measurements obtained before, during and after user inhalation, wherein the light intensity measurements in this example are associated with light transmitted through a glass section of conduit  1312 , as described below. 
     As shown in  FIG. 13 , vape device  1300  includes a light source  1314  and a light detector  1316  spaced apart from each other within housing  1302  outside of conduit  1312  between atomizer  1310  and outlet  1306 . Also, in this example, conduit  1312  includes a flat or curved section made of glass, plastic, or another material with an index of refraction that is sufficiently similar to that of the payload and sufficiently different from that of air, as discussed above, which will be referred to herein as a “glass section  1318 ” for ease of reference. Glass section  1318  extends along the length of conduit  1312  such that one end of glass section  1318  is positioned adjacent light source  1314  and the other end of glass section  1318  is positioned adjacent light detector  1316 . 
     The light path between light source  1314  and light detector  1316  through glass section  1318  can be understood from the description of  FIGS. 11B and 11C  above, wherein light detector  1316  is configured to generate a signal representing the intensity of the received light. As discussed above, light source  1314  and light detector  1316  are incorporated into a light intensity measurement circuit configured to obtain a plurality of light intensity measurements before, during and after each user inhalation and provide such measurements to the microcontroller of vape device  1300 . 
     It should be understood that various modifications could be made to vape device  1300  within the scope of the present invention. For example, in some embodiments, a mirrored coating may be applied to the non-vapor side of glass section  1318 , i.e., the outside surface of glass section  1318 . In this case, light would still escape glass section  1318  when vaporized payload is deposited on the inside surface of glass section  1318 . In other embodiments, all of conduit  1312  (not just glass section  1318 ) may be made of glass—either with or without a mirrored coating on the outside surface of conduit  1312 . In yet other embodiments, glass section  1318  is made of another material having an index of refraction similar to that of the vaporized payload, as discussed above. Of course, other modifications will be apparent to those skilled in the art. 
     It should also be understood that any of vape devices  1100 ,  1200  and  1300  could be modified by placing a mirrored finish on the far end of the light transmitting medium from the light source so that the light sensor may be co-located with the light source. If the vape device includes a cartridge and a control assembly formed in separate housings that are releasably connected to each other via an electromechanical connection, as described above, this modification would enable the light source and/or the light detector to be positioned within the control assembly while the light transmitting medium is located within the cartridge (similar to the configurations shown in  FIGS. 8-10 ). 
     Of course, other modifications to vape devices  1100 ,  1200  and  1300  will be apparent to those skilled in the art. For example, the glass fiber may be oriented at any angle within the conduit and is not limited to being positioned parallel to the direction of airflow (as in the vape device of  FIG. 11A ) or perpendicular to the direction of airflow (as in the vape device of  FIG. 12 ). In addition, the glass fiber may follow the contour of the conduit, either in a direct line or helix. 
     Further, in each of the vape devices shown in  FIGS. 6-13  above, the light intensity measurement circuit is configured to provide the light intensity measurements obtained during user inhalation (and optionally before and after user inhalation) to the microcontroller of the vape device. In some embodiments, the microcontroller is programmed to determine the dose of payload that is vaporized during each user inhalation by performing the following steps: (1) acquiring a plurality of light intensity measurements from the light intensity measurement circuit during user inhalation (and optionally before and after user inhalation) and (2) using the information from step 1 to determine the vapor density of the vaporized payload and by extension the partial mass of the payload that is vaporized during user inhalation. 
     In some embodiments, the method may be further refined (optionally) by varying the intensity of the light signal emitted by the light source and/or the gain of the light detector in order to adjust the sensitivity. 
     In some embodiments, the method may be further refined (optionally) by applying an electric field to the air flow chamber so as to orient a plurality of molecules in the vaporized payload when the vaporized payload passes through the conduit in order to improve their reflective properties. 
     Finally, it should be understood that all or a portion of the processing steps performed by the microcontroller of the vape device, as described above, could alternatively be performed by one or more other microcontrollers, such as a secondary microcontroller positioned in a cartridge of the vape device (for embodiments in which the vape device comprises a cartridge releasably connected to a control assembly). Various embodiments will be apparent to those skilled in the art. 
     Dose Determination/Vapor Droplet Counting Method Using Hot Wire Anemometers 
     In some embodiments, the vape device utilizes two or more hot wire anemometers to determine the mass of the vaporized payload that was delivered to the user during each user inhalation and/or to determine the size and density distribution of the droplets in the vaporized payload and use such distribution to calculate the total mass of the vaporized payload that was delivered to the user during each user inhalation. 
     Referring to  FIG. 14 , an example of a vape device that relies on this method to determine the dose of vaporized payload is shown generally as reference numeral  1400 . Vape device  1400  includes a housing  1402 , which may comprise an internal housing or external housing of vape device  1400 . Positioned within housing  1402  is an air flow chamber which, in this example, comprises a conduit  1412  that extends between an inlet  1404  and an outlet  1406 . It can be appreciated that the inlet and outlet orifices are defined by conduit  1412 . An atomizer  1410  is positioned anywhere between inlet  1404  and outlet  1406 . As described above, atomizer  1410  is configured to heat and vaporize the payload contained in a payload reservoir (not shown) so as to output a vaporized payload. During a user inhalation, ambient air flows through conduit  1412  from inlet  1404  to atomizer  1410 , and ambient air mixed with vaporized payload flows through conduit  1412  from atomizer  1410  to outlet  1406 . Outlet  1406  may further be in communication with a mouthpiece, as described above. Of course, it should be understood that vape device  1400  may include a number of other components that are not specifically shown in  FIG. 14 , including a power source, a microcontroller, and other electronics, as described above in connection with vape devices  10  and  100 . 
     With respect to vape device  1400 , the microcontroller is programmed to control the power source (e.g., a battery) so that the power source transmits a power signal (e.g., a direct current or pulsed direct current) to atomizer  1410  in accordance with desired operational settings. When the heating element of atomizer  1410  reaches the vaporization temperature of the payload contained in the payload reservoir, a portion of the payload is vaporized to thereby generate the vaporized payload for user inhalation. 
     A rough dose estimate for each user inhalation can be determined by integrating the power draw versus time of the heating element of atomizer  1410  and comparing it with the amount of payload theoretically vaporized based on the specific heat and heat of vaporization of the payload. However, this dose estimate may not be accurate enough for critical pharmaceutical delivery applications, especially in the case of multi-component payloads in which partial fractionation of the mixture may occur at the interface between the wick and heating element of atomizer  1410 . Therefore, in order to provide a more accurate and repeatable measurement of the total mass of the payload vaporized during each user inhalation, vape device  1400  may utilize a number of different components and circuits, as described below. 
     In this example, vape device  1400  includes three hot wire anemometers—a reference hot wire anemometer  1414  located within conduit  1412  between inlet  1404  and atomizer  1410  and two sampling hot wire anemometers  1416  and  1418  located within conduit  1412  between atomizer  1410  and outlet  1406 . The wire filament of each of these anemometers may be made of tungsten, platinum or platinum-iridium, although other materials known to those skilled in the art may also be used. 
     Vape device  1400  also includes two temperature sensors—a first temperature sensor  1420  located within conduit  1412  between inlet  1404  and atomizer  1410  and a second temperature sensor  1422  located within conduit  1412  between atomizer  1410  and outlet  1406 . Each of temperature sensors  1420  and  1422  may comprise any type of component capable of sensing the temperature at the designated locations, such as a thermistor, a thermocouple, an infrared sensor, a bandgap temperature sensor, an analog temperature sensor, or a digital temperature sensor. Of course, those skilled in the art will understand that other types of temperature sensors may be used in accordance with the present invention. 
     Reference hot wire anemometer  1414  is incorporated into a circuit configured to measure the velocity of air flowing over the wire. The circuit may comprise, for example, a constant temperature Wheatstone bridge circuit, as known to those skilled in the art. During each user inhalation, an electric current is sent through the wire, causing the wire to become hot. As air flows over the wire, it cools the wire and removes some of its heat energy. By integrating the instantaneous heat loss from the wire over time, the anemometer provides a baseline reading of the air flow rate through conduit  1412  during user inhalation, which may be used along with the information from sampling hot wire anemometers  1416  and  1418  (discussed below) to determine the dose of the vaporized payload. 
     Sampling hot wire anemometer  1416  is incorporated into a circuit configured to measure the mass of vaporized payload passing by the wire during each user inhalation. By passing current through the wire of hot wire anemometer  1416  so that it operates at a temperature that is above the boiling point of each of the components in the payload, individual collisions of the wire with the droplets in the vaporized payload can be measured. Goldschmidt, Victor W. “Measurement of Aerosol Concentrations with a Hot Wire Anemometer,”  Journal of Colloid Science  20, 617-634 (1965). Counting the number of droplets detected over time can serve as input in determining the total mass of vaporized payload delivered during each user inhalation, provided the size distribution of the droplets in the vaporized payload is known, narrow and constant. This enables the accuracy of the dose determination to be significantly improved. It should be understood that sampling hot wire anemometer  1418  operates in the same manner. 
     Sampling hot wire anemometers  1416  and  1418  may also be operated at different temperatures to enable detection of different components in the vaporized payload. For example, assume that the vaporized payload contains components A and B, wherein the boiling point of component A is lower than the boiling point of component B. In this case, hot wire anemometer  1416  is operated at a temperature that is higher than the boiling point of component A, but lower than the boiling point of component B. Also, hot wire anemometer  1418  is operated at a temperature that is higher than the boiling points of components A and B. It can be appreciated that this arrangement enables the dose of each of components A and B to be determined. 
     It should be noted that sampling hot wire anemometer  1416  may be fouled by deposition of component B. In order to address this issue, the “roles” of sampling hot wire anemometers  1416  and  1418  may be swapped between successive user inhalations (i.e., the operating temperatures of the anemometers are successively swapped) so that component B is vaporized over the course of using vape device  1400 . 
     First temperature sensor  1420  is incorporated into a first temperature measurement circuit configured to obtain a plurality of temperature measurements during user inhalation in order to determine the ambient temperature of the incoming air. Second temperature sensor  1422  is incorporated into a second temperature measurement circuit configured to obtain a plurality of temperature measurements during user inhalation in order to determine the temperature of the vaporized payload/air mixture. This data may be used along with the information from reference hot wire anemometer  1414  and sampling hot wire anemometers  1416  and  1418  to determine the dose of the vaporized payload. 
     The above implementation is suitable for cases in which the size distribution of the droplets in the vaporized payload is known, narrow and constant. However, if the distribution of droplet sizes is wide and changing over the duration of the user inhalation, the accuracy of the dose determination will suffer. In order to address these issues, it is preferable to utilize a component and circuit arrangement that enables the microcontroller to determine the size and density distribution of the droplets in the vaporized payload and use such distribution to calculate the total mass of the vaporized payload that was delivered to the user during each user inhalation. 
       FIG. 15  shows an exemplary embodiment of such a component and circuit arrangement that may be incorporated into a vape device. In this example, the vape device includes a reference hot wire anemometer that operates in the same manner as reference hot wire anemometer  1414  described above. The vape device also includes an array of sampling hot wire anemometers (SHWAT 1 , SHWAT 2 , SHWAT 3  . . . SHWAT m-1 , SHWAT m ) each of which operates at a distinct temperature (T 1 , T 2 , T 3  . . . T m-1 , T m ) in order to enable detection of different components in the vaporized payload, as described above. In addition, the vape device includes two thermistors (Thermistor  1  and Thermistor  2 ) that operate in the same manner as temperature sensors  1420  and  1422  described above. 
     It can be seen that each of the sampling hot wire anemometers (SHWAT 1 , SHWAT 2 , SHWAT 3  . . . SHWAT m-1 , SHWAT m ) are connected to an array of monostable multivibrator (one shot) modules with different triggering thresholds (MM-TT 1 , MM-TT 2 , TT 3  . . . MM-TT n-1 , MM-TT n ) and an array of associated digital counters (DC-TT 1 , DC-TT 2 , DC-TT 3  . . . DC-TT n-1 , DC-TT n ,). The triggering thresholds of the monostable multivibrator modules are segmented to cover bands of droplet size detection sensitivity in order to more granularly determine the droplet size distribution and density in the vaporized payload. 
     Specifically, each of the monostable multivibrator modules has an individual triggering threshold tailored to be sensitive to a droplet of a minimum size. For example, the most sensitive monostable multivibrator module would count every size droplet, and the second most sensitive monostable multivibrator module would count every size droplet except the smallest size droplet. By subtracting the number of droplets detected by the second most sensitive monostable multivibrator module from the number of droplets detected by the most sensitive monostable multivibrator module, the number of the smallest size droplets within that band can be determined. This scheme can be extended until the desired number of droplet size bands is represented. The size and density distribution of the droplets in the vaporized payload may then be integrated over the time period of the user inhalation in order to calculate the total mass of the vaporized payload that was delivered to the user during each user inhalation. 
     In some embodiments, a standardized aerosol generator may be used to calibrate the vape device using various droplet size and density settings. 
     Finally, it should be understood that all or a portion of the processing steps performed by the microcontroller of vape device  1400 , as described above, could alternatively be performed by one or more other microcontrollers, such as a secondary microcontroller (not shown) positioned in a cartridge of vape device  1400  (for embodiments in which vape device  1400  comprises a cartridge releasably connected to a control assembly). Various embodiments will be apparent to those skilled in the art. 
     Dose Control System 
     The methods of measuring dosage described above may be used independently, or in any combination, to record the dose administered to the user and report it to personal computing device  72  or an equivalent device. Alternatively, the desired dose can be set in advance by the user through an on-vaporizer input method (e.g., buttons, dial, etc.) or through interaction with application  74  running on personal computing device  72 . The user then inhales until the user-specified dose is administered, at which point the vape device stops vaporizing to thereby provide an accurate means of dose control. 
     III. General Information 
     In this disclosure, the use of any and all examples or exemplary language (e.g., “for example” or “as an example”) is intended merely to better describe the invention and does not pose a limitation on the scope of the invention. No language in the disclosure should be construed as indicating any non-claimed element essential to the practice of the invention. 
     Also, the use of the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a system, device, or method that comprises a list of elements does not include only those elements, but may include other elements not expressly listed or inherent to such system, device, or method. 
     Further, the use of relative relational terms, such as first and second, are used solely to distinguish one unit or action from another unit or action without necessarily requiring or implying any actual such relationship or order between such units or actions. 
     Finally, while the present invention has been described and illustrated hereinabove with reference to various exemplary embodiments, it should be understood that various modifications could be made to these embodiments without departing from the scope of the invention. For example, while the methods of measuring dosage are described above for use in a vape device, some of these methods (e.g., the light measurement methods and/or hot wire anemometer methods) could be used in a nebulizer. Therefore, the present invention is not to be limited to the specific structural configurations, circuits or methodologies of the exemplary embodiments, except insofar as such limitations are included in the following claims.