Aerosol-generating system with fluid sensor

A vapor-generating system includes a pump having an inlet and an outlet, the inlet configured to be connected to a liquid storage portion. The system includes a fluid channel fluidly connected to the pump and a fluid sensor. The fluid sensor is configured to determine a presence of liquid vapor-forming substrate in the fluid channel based on measuring an electrical property of the fluid in the fluid channel.

BACKGROUND

Field

Some example embodiments relate to a vapor-generating system with a pump having an inlet and an outlet, the inlet being connectable to a liquid storage portion and a fluid channel. Some example embodiments relate to a method for generating a vapor.

Description of Related Art

One type of vapor-generating system (also called an aerosol-generating system) comprises a liquid storage portion, a pump and a vaporizer. During a puff of a user (“adult vaper”) (e.g., air being drawn through an airflow path of the system by an adult vaper), a stream of liquid vapor-generating substrate (e.g., e-liquid) is actively pumped from the liquid storage portion to the vaporizer by means of the pump. In such a system—when the liquid in the liquid storage portion is used up (“depleted”)—the vaporizer may be heated, while no liquid vapor-generating substrate is provided to the vaporizer. As a result, heated air, which does not contain a generated vapor, may be drawn. Drawing heated air only may be unpleasant for the adult vaper and is thus unwanted. Also, heating of the vaporizer or a wicking material when there is no liquid present may result in the release of undesirable products.

It would therefore be desirable to provide an improved vapor-generating system which prevents activation of the system once the liquid vapor-generating substrate in the liquid storage portion is used up.

SUMMARY

According to some example embodiments, a vapor-generating system may include a fluid channel fluidly connected to a liquid source, and a fluid sensor. The fluid sensor may be configured to generate a sensor signal indicating a presence of liquid vapor-forming substrate in the fluid channel based on measuring an electrical property of a fluid in the fluid channel.

The vapor-generating system may further include a dispensing device configured to dispense the liquid vapor-forming substrate, the dispensing device in fluid communication with the liquid source.

The fluid channel and the fluid sensor may be between the liquid source and the dispensing device.

The electrical property may be an electrical resistance of the fluid in the fluid channel.

The fluid sensor may include a first electrode and a second electrode.

The first electrode may be at a first channel wall of the fluid channel, the second electrode may be at a second channel wall of the fluid channel, and the first electrode and the second electrode may be both in direct contact with the fluid in the fluid channel.

The first electrode may be at an opposite channel wall in relation to the second electrode.

The fluid sensor may include a voltage divider circuit.

The sensor signal may indicate a type of fluid based on the electrical property of the fluid in the fluid channel.

The liquid source may include a micropump, a micro stepper motor pump, or a piezoelectric pump.

The vapor-generating system may further include a vaporizer and a controller. The controller may be configured to deactivate the vaporizer based on processing the sensor signal generated by the fluid sensor to determine that no fluid is in the fluid channel or a wrong fluid is in the fluid channel.

The vapor-generating system may further include a main body, the main body including a power supply, wherein the liquid source, the dispensing device, the fluid channel and the fluid sensor are encompassed in the main body, wherein the liquid storage portion is included in a cartridge, the cartridge configured to be releasably connected to the main body.

According to some example embodiments, a method for generating a vapor may include providing a liquid source configured to supply a liquid vapor-forming substrate, fluidly connecting a fluid channel to the liquid source, and coupling a fluid sensor to the fluid channel, such that the fluid sensor is configured to generate a sensor signal indicating a presence of the liquid vapor-forming substrate in the fluid channel based on measuring an electrical property of a fluid in the fluid channel.

The method may further include providing a controller, the controller configured to deactivate a vaporizer based on processing the sensor signal generated by the fluid sensor to determine that no fluid is in the fluid channel, or a wrong fluid is in the fluid channel.

The electrical property may be an electrical resistance of the fluid in the fluid channel.

The fluid sensor may include a first electrode and a second electrode.

The first electrode may be at a first channel wall of the fluid channel, the second electrode may be at a second channel wall of the fluid channel, and the first electrode and the second electrode may be both in direct contact with the fluid in the fluid channel.

The first electrode may be at an opposite channel wall in relation to the second electrode.

The fluid sensor may include a voltage divider circuit.

The sensor signal may indicate a type of fluid based on the electrical property of the fluid in the fluid channel.

DETAILED DESCRIPTION

Example embodiments will become more readily understood by reference to the following detailed description of the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as being limited to the example embodiments set forth herein. Rather, these example embodiments are provided so that this disclosure will be thorough and complete. Like reference numerals refer to like elements throughout the specification.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, regions, layers and/or sections, these elements, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, region, layer or section from another region, layer or section. Thus, a first element, region, layer or section discussed below could be termed a second element, region, layer or section without departing from the teachings set forth herein.

As disclosed herein, the term “storage medium”, “computer readable storage medium” or “non-transitory computer readable storage medium,” may represent one or more devices for storing data, including read only memory (ROM), random access memory (RAM), magnetic RAM, core memory, magnetic disk storage mediums, optical storage mediums, flash memory devices and/or other tangible machine readable mediums for storing information. The term “computer-readable medium” may include, but is not limited to, portable or fixed storage devices, optical storage devices, and various other mediums capable of storing, containing or carrying instruction(s) and/or data.

When the terms “about” or “substantially” are used in this specification in connection with a numerical value, it is intended that the associated numerical value include a tolerance of ±10% around the stated numerical value. The expression “up to” includes amounts of zero to the expressed upper limit and all values therebetween. When ranges are specified, the range includes all values there between such as increments of 0.1%. Moreover, when the words “generally” and “substantially” are used in connection with geometric shapes, it is intended that precision of the geometric shape is not required but that latitude for the shape is within the scope of the disclosure.

According to some example embodiments there is provided a vapor-generating system (also called an aerosol-generating system), comprising a pump having an inlet and an outlet, the inlet being connectable to a liquid storage portion. The pump and liquid storage portion may be referred to herein as collectively comprising a “liquid source.” The system also comprises a fluid channel fluidly connected to the pump and a fluid sensor (thereby being fluidly connected to a liquid source). The fluid sensor is configured to generate a sensor signal based on measuring an electrical property of the fluid in the fluid channel. In some example embodiments, the fluid sensor is configured to generate a sensor signal indicating a presence of liquid vapor-forming substrate (also called an aerosol-forming substrate) in the fluid channel, for example based on measuring an electrical property of the fluid in the fluid channel. The sensor signal may be processed (e.g., by a controller as described herein) in order to determine (“detect”) the presence of liquid vapor-forming substrate in the fluid channel. Such a determination (“detection”) may be understood to be performed by an element performing the processing of the sensor signal (e.g., the controller).

The vapor-generating system of some example embodiments allows (“enables”) detection of the presence of liquid vapor-forming substrate in the fluid channel. Beneficially, a vaporizer of the system can be deactivated when the fluid sensor generates a sensor signal that provides an indication that no fluid is present in the fluid channel, thereby enabling a controller to determine (“detect”) that no fluid is present in the fluid channel based on processing the sensor signal generated by the fluid sensor. The drawing of only hot air is thus prevented, thereby prohibiting an unpleasant experience for the adult vaper and the generation of undesirable products. The sensor signal, generated by the fluid sensor, indicating that no more liquid vapor-forming substrate is present in the fluid channel, and furthermore the determination that no more liquid vapor-forming substrate is present in the fluid channel based on a processing of the sensor signal, may be utilized to make a determination, and further provide an indication, that a fresh liquid storage portion must be supplied.

The vapor-generating system may further comprise a dispensing device for dispensing (“configured to dispense”) the liquid vapor-forming substrate, wherein the dispensing device is in fluid communication with the outlet of the pump. The fluid channel and the fluid sensor may be provided (“located”) between the pump and the dispensing device. The fluid sensor may be provided adjacent to the dispensing device, wherein the dispensing device may be provided adjacent to the vaporizer. However, the fluid sensor may be provided anywhere in the system between the liquid storage portion (e.g., the liquid source) and the dispensing device.

If the fluid sensor is provided downstream of the pump between the pump and the dispensing device and/or downstream of the liquid source between the liquid source and the dispensing device, the liquid vapor-forming substrate can be optimally used, since all of the liquid vapor-forming substrate is consumed before the sensor generates a sensor signal that provides an indication that no more liquid is present in the fluid channel. In more detail, even if the liquid in the liquid storage portion is used up, liquid may still be present in the fluid channel. In this case, the system will still operate, until the fluid in the fluid channel downstream of the pump is used up. Thus, the liquid storage portion may be completely depleted of liquid vapor-forming substrate before the fluid sensor generates a sensor signal that provides an indication that no more substrate is present.

The fluid sensor may be configured to measure an electrical property of the fluid comprised in the fluid channel. The electric property measured by the fluid sensor may be the electrical resistance of the fluid comprised in the fluid channel.

Typical fluids in the fluid channel include ambient air or liquid vapor-forming substrate. When the liquid storage portion still comprises liquid vapor-forming substrate and the substrate is pumped towards the dispensing device by the pump, the substrate will be present in the fluid channel. If, however, the liquid storage portion is emptied of substrate, no more substrate will subsequently be pumped through the fluid channel. Thus, ambient air will be present in the fluid channel. The electrical resistance of ambient air is different from the electrical resistance of liquid vapor-forming substrate. Typically, the electrical resistance of ambient air is higher than the electrical resistance of liquid vapor-forming substrate. Thus, by measuring the electrical resistance of the fluid comprised in the fluid channel, the sensor may determine whether air or substrate is present in the fluid channel.

To be configured to measure the electrical resistance of the fluid comprised in the fluid channel, the fluid sensor may comprise (“include”) a first electrode and a second electrode.

The resistance between the first electrode and the second electrode may depend on the amount of liquid vapor-forming substrate held (“located”) in the liquid channel. For example, the electrical resistance may increase as the amount of liquid vapor-forming substrate held in the fluid channel decreases.

The electrodes may be arranged (“located”) at walls of the fluid channel. For example, the first electrode is provided at a first channel wall of the fluid channel and the second electrode is provided at a second channel wall of the fluid channel. The electrodes may be both in direct contact with the fluid comprised in the fluid channel. The first electrode may be disposed opposite to the second electrode. Restated, the first electrode may be at an opposite channel wall in relation to the second electrode. The electrodes may alternatively be arranged in the liquid channel. The first electrode and the second electrode may be arranged at opposite ends of the liquid channel. At least one of the first and second electrodes may be arranged at or in contact with the wall of the liquid channel. The first and second electrodes may be arranged to each partially surround the liquid channel. The first and second electrodes may be arranged concentrically about a common axis of the liquid channel.

The second electrode may substantially follow the path of the first electrode. This may enable the spacing between the first and second electrodes to remain consistent along the length of the first and second electrodes. The second electrode may be arranged substantially parallel to the first electrode.

The electrodes may be any suitable type of electrode. For example, suitable types of electrodes include point electrodes, ring electrodes, plate electrodes or track electrodes. The first electrode and the second electrode may be the same type of electrode. The first electrode and the second electrode may be different types of electrodes.

The electrodes may by any suitable shape. For example, the electrodes may be: square, rectangular, curved, arcuate, annular, spiral or helical. The electrodes may be substantially cylindrical. The electrodes may comprise one or more sections that are substantially linear, non-linear, planar or non-planar. The electrodes may be rigid. This may enable the electrodes to maintain their shape. The electrodes may be flexible. This may enable the electrodes to conform to the shape of the fluid channel.

The electrodes may have a length, a width and a thickness. The length of the electrodes may be substantially greater than the width of the electrodes. In other words, the electrodes may be elongate. The thickness of the electrodes may be substantially less than the length and the width of the electrodes. In other words, the electrodes may be thin. Thin electrodes and elongate electrodes may have a larger surface area to volume ratio. This may improve the sensitivity of measurements.

The electrodes may comprise any suitable material. The electrodes may comprise any suitable electrically conductive material. Suitable electrically conductive materials include metals, alloys, electrically conductive ceramics and electrically conductive polymers. The materials may include gold and platinum. The electrodes may be coated with a passivation layer. The electrodes may comprise or be coated in material that is sufficiently non-reactive so as not to react with or contaminate the liquid vapor-forming substrate. The electrodes may comprise transparent or translucent material.

To be configured to measure the electrical resistance, the fluid sensor may comprise a voltage divider circuit. A voltage divider circuit enables the measurement of (“is configured to measure”) the electric resistance between the first and second electrode of the fluid sensor. However, any known method of measuring the resistance of the fluid between the two electrodes may be employed.

The measured electrical property of the fluid may also be the dielectric constant of the fluid. In this regard, the electrodes may constitute a capacitor. The fluid between the electrodes serves—in this case—as a dielectric medium, wherein the dielectric constant of this fluid may be measured by measuring the capacitance of the capacitor or any known method. The dielectric constant of air is different from the dielectric constant of liquid vapor-forming substrate and can be used to distinguish these fluids.

The electric property, for example the electric resistance or dielectric constant of the fluid in the fluid channel may be indicative of the specific fluid (e.g., a “type” of fluid of the fluid in the fluid channel). By determining the electrical resistance of the fluid in the fluid channel, it may be possible to identify the chemistry of the liquid. In this regard, the electrical resistance of the fluid in the fluid channel may depend upon the chemistry of the liquid. Thus, it may be identified whether or not the correct type of liquid is used. For example, different liquid vapor-forming substrates may be used in the system by subsequently providing liquid storage portions with different substrates. These different substrates may have different electric properties, which may be detectable based on processing one or more sensor signals generated by the fluid sensor. The sensor signals generated by the fluid sensor may be processed to not only detect whether or not substrate is present in the fluid channel, but additionally detect what kind of substrate is present in the fluid channel. Beneficially, the system may be operated on basis of the detection of the specific substrate based on processing one or more sensor signals generated by the fluid sensor. For example, the temperature of a vaporizer may be controlled depending on the used substrate. Also, the heating time may be controlled depending on the used substrate.

The dispensing device may be a nozzle or a tubing segment, also referred to as tube. The dispensing device may comprise a tube and a nozzle at the distal end of the tube. The tube may comprise any appropriate material, for example glass, metal, for example stainless steel, or plastics material, for example PEEK. The size of the tube may match that of the pump outlet. For example, the tube may have a diameter of about 1 to 2 millimeters but other sizes are possible. The tube may be connected to the pump outlet via silicon tubing. The tube may be directly connected to the pump outlet.

The dispensing device may be provided to deliver the liquid vapor-forming substrate to a vaporizer. The vaporizer may comprise a heater for heating the supplied amount of liquid vapor-forming substrate. The heater may be any device suitable for heating the liquid vapor-forming substrate and volatilizing at least a part of the liquid vapor-forming substrate in order to form a vapor. The heater may be a heated coil, a heated capillary, a heated mesh or a heated metal plate. For example, the vaporizer may be provided as a heating coil extending—with respect to the dispensing device—in a longitudinal direction of the dispensing device. The diameter of the heating coil may be chosen such that the heating coil can be mounted around the dispensing device. The heating coil may be mounted transverse to the dispensing device. The heating coil may overlap with the nozzle of the dispensing device. In some examples, there may be a distance between the nozzle of the dispensing device and the heating coil. The length of the heating coil may be 2 millimeters to 9 millimeters, including 3 millimeters to 6 millimeters. The diameter of the heating coil may be 1 millimeter to 5 millimeters, for example 2 millimeters to 4 millimeters.

The heater may comprise only a single heating element or a plurality of heating elements. The temperature of the heating element or elements is preferably controlled by electric circuitry (e.g., a controller).

The electric circuitry may comprise a microprocessor, which may be a programmable microprocessor. The microprocessor may be part of a controller. The electric circuitry may comprise further electronic components. The controller may be configured to regulate a supply of power to the vaporizer. Power may be supplied to the vaporizer continuously following activation of the system or may be supplied intermittently, such as on a puff-by-puff (“draw-by-draw”) basis. The power may be supplied to the vaporizer in the form of pulses of electrical current. In some example embodiments, the supply of power to the vaporizer is controlled depending upon the measurement of the fluid sensor. The controller may be configured to process one or more sensor signals generated by the fluid sensor. The controller may be configured to make determinations and/or detections based on processing the one or more sensor signals generated by the fluid sensor. When the fluid sensor generates a sensor signal that may be processed (e.g., by a controller as described herein) to determine (“detect”) that no more liquid is present in the fluid channel, power supply to the vaporizer may be prohibited by the controller in response to said determining (“detecting”). Additionally or alternatively, the power supply to the vaporizer may be controlled (e.g., by the controller) on basis of (“based on”) the type of liquid vapor-forming substrate in the fluid channel. For example, the specific heating regime may be executed on basis of the type of substrate. In another example, the power supply to the vaporizer may be prohibited (e.g., the vaporizer may be deactivated), for example by the controller, based on a sensor signal generated by the fluid sensor being processed (e.g., by the controller) to determine (e.g., such that the controller determines) that no fluid is in the fluid channel or a wrong fluid is in the fluid channel.

To be configured to supply power to the vaporizer, the system may comprise a power supply, typically a battery. In some example embodiments, the power supply may be another form of charge storage device such as a capacitor. The power supply may require recharging and may have a capacity that allows for the storage of enough energy for one or more experiences; for example, the power supply may have sufficient capacity to allow for the continuous generation of vapor for a period of several minutes. In another example, the power supply may have sufficient capacity to allow for a particular (or, alternatively, predetermined) number of puffs (“draws”) or discrete activations of the vaporizer. The controller may be connected to the power supply and thus may be configured to control the supply of power from the power supply to the vaporizer, for example based on determinations made by the controller as a result of processing one or more sensor signals generated by the fluid sensor.

The vaporizer may also be a piezoelectric transducer or vibrating membrane.

The pump may be a micro pump. The pump may also be provided as a micro stepper motor pump or a piezoelectric pump.

The pump may be controlled by the controller. The controller may stop the operation of the pump based on a determination, via processing of one or more sensor signals generated by the fluid sensor, that no more liquid vapor-forming substrate is present in the fluid channel. Power may be supplied to the pump by means of the power supply.

The pump and/or the vaporizer may be triggered by a puff detection system (“draw detection system”). In some example embodiments, the pump and/or the vaporizer may be triggered based on adult vaper interaction with an on-off button of the system, held for the duration of air being drawn through an airflow path of the system.

The draw detection system may a sensor, which may be configured as an airflow sensor and may measure the airflow rate. The airflow rate is a parameter characterizing the amount of air that is drawn through the airflow path of the system per time by the adult vaper. The initiation of the draw may be detected based on processing sensor signals generated by the airflow sensor when the airflow exceeds a particular (or, alternatively, predetermined) threshold.

The sensor may be configured to generate an output indicative of a magnitude and direction of the airflow, and the controller may receive the sensor output and determine if the following ‘wiping conditions’ exist: (1) a direction of the airflow indicates a draw on an outlet of the system (versus air entering the system through the outlet), and (2) a magnitude of the airflow exceeds a threshold value. If these internal conditions are met, the controller may electrically connect the power supply to the pump and/or vaporizer, thereby activating same. In some example embodiments, the sensor may generate an output indicative of a pressure drop within the housing of the system (which is caused by a draw of air entering the system), whereupon the controller activates the vaporizer and/or pump, in response thereto. The sensor may be a sensor as disclosed in “Electronic Smoke Apparatus,” U.S. application Ser. No. 14/793,453, filed on Jul. 7, 2015 and published as U.S. Publication No. 2015/0305410, or a sensor as disclosed in “Electronic Smoke,” U.S. Pat. No. 9,072,321, issued on Jul. 7, 2015, each of which is hereby incorporated by reference in their entirety into this document.

The liquid storage portion may be adapted for storing (“configured to store”) the liquid vapor-forming substrate to be supplied to the dispensing device. The liquid storage portion may be configured as a container or a reservoir for storing the liquid vapor-forming substrate.

In some example embodiments, the liquid storage portion is capable of being coupled to the pump inlet by a respective coupling hermetically sealed against surrounding atmosphere. In some example embodiments, the couplings are configured as self-healing pierceable membranes. The membranes avoid undesired leaking of the liquid vapor-forming substrate stored in the liquid storage portion. To be configured to couple the replaceable liquid storage portion to the pump a respective needle-like hollow tube may be pierced through a respective membrane. When the pump is coupled to the liquid storage portion, the membranes avoid undesired leaking of the liquid vapor-forming substrate and leaking of air from and into the liquid storage portion.

The liquid storage portion may be any suitable shape and size. For example, the liquid storage portion may be substantially cylindrical. The cross-section of the liquid storage portion may, for example, be substantially circular, elliptical, square or rectangular.

The liquid storage portion may be a disposable article replaced once the liquid storage portion is empty or below a minimum volume threshold. The system may output a signal such as an optical or acoustical signal based on a detection (e.g., by the controller based on processing a sensor signal generated by the fluid sensor) that the fluid channel is empty of liquid vapor-forming substrate. The signal may indicate that a new liquid storage portion must be provided to replace the old empty liquid storage portion or that the liquid storage portion needs to be refilled.

The vapor-forming substrate is a substrate capable of releasing volatile compounds that can form a vapor. The volatile compounds may be released by heating the vapor-forming substrate. The vapor-forming substrate may comprise plant-based material. The vapor-forming substrate may comprise tobacco. The vapor-forming substrate may comprise a tobacco-containing material containing volatile tobacco flavor compounds, which are released from the vapor-forming substrate upon heating. The vapor-forming substrate may alternatively comprise a non-tobacco-containing material. The vapor-forming substrate may comprise homogenized plant-based material. The vapor-forming substrate may comprise homogenized tobacco material.

In some example embodiments, a tobacco material may include material from any member of the genusNicotiana. In some example embodiments, the tobacco material includes a blend of two or more different tobacco varieties. Examples of suitable types of tobacco materials that may be used include, but are not limited to, flue-cured tobacco, Burley tobacco, Maryland tobacco, Oriental tobacco, rare tobacco, specialty tobacco, dark tobacco, blends thereof and the like. The tobacco material may be provided in any suitable form, including, but not limited to, tobacco lamina, processed tobacco materials, such as volume expanded or puffed tobacco, processed tobacco stems, such as cut-rolled or cut-puffed stems, reconstituted tobacco materials, blends thereof, and the like. In some example embodiments, the tobacco material is in the form of a substantially dry tobacco mass.

The vapor-generating system may be an electrically operated system. In some example embodiments, the vapor-generating system is portable. The vapor-generating system may have a size comparable to a conventional cigar or cigarette. The system may have a total length between approximately 30 millimeters and approximately 150 millimeters. The system may have an external diameter between approximately 5 millimeters and approximately 30 millimeters.

According to some example embodiments, there is provided a method for generating a vapor. The method comprises the step of providing a pump for pumping liquid vapor-forming substrate, the pump having an inlet and an outlet, the inlet being connectable to a liquid storage portion. A fluid channel is provided fluidly connected to the pump. Furthermore, a fluid sensor is provided, wherein the fluid sensor determines a presence of liquid vapor-forming substrate in the fluid channel.

Features described in relation to one aspect may equally be applied to some example embodiments.

FIG.1shows an illustrative cross section of a vapor-generating system according to some example embodiments. The vapor-generating system shown inFIG.1comprises a fluid sensor10. The fluid sensor10is arranged between a pump12and a dispensing device14. The fluid sensor10is arranged at (e.g., is coupled to, is in fluid communication with, etc.) a fluid channel16. The fluid sensor10may measure the electrical resistance of the fluid in the fluid channel16. Thereby, the fluid sensor10may generate a sensor signal that indicates whether liquid vapor-forming substrate is present in the fluid channel16. Such a sensor signal may be processed by another element (e.g., a controller as described herein) to enable the other element to make a determination (e.g., “to detect”) whether liquid vapor-forming substrate is present in the fluid channel16.

The pump12is configured to pump liquid vapor-forming substrate from a liquid storage portion18towards the fluid channel16and the fluid sensor10. The pump12is fluidly connected with the liquid storage portion18by means of an additional fluid channel20. Collectively, the pump12and the liquid storage portion18may be referred to herein as a “liquid source.”

After the liquid vapor-forming substrate passes the fluid channel16and the fluid sensor10, the liquid vapor-forming substrate is delivered towards the dispensing device14. The dispensing device14is configured as a tubing segment ending in a nozzle22. Around the dispensing device14, a heater24is arranged. The heater24is configured as a heating coil.

The heater24heats the liquid vapor-forming substrate in the dispensing device14such that a vapor is delivered from the nozzle22towards a mouth end (“outlet end”)26of the vapor-generating system. The vapor is subsequently drawn to an outlet of the system. The heater24is powered by a battery28.

The fluid sensor10, pump12, dispensing device14, fluid channel16, nozzle22, heater24, outlet end26and battery28are arranged in a housing30. The housing30confines a main body of the system. The housing30also comprises a controller32. The controller32controls the activation of the heater24. When the fluid sensor10generates a sensor signal that indicates that no liquid vapor-forming substrate is present in the fluid channel16, and the controller32processes the sensor signal to determine (“detect”) that no liquid vapor-forming substrate is present in the fluid channel16, the controller32will deactivate the heater24. The controller32also controls the pumping action of the pump12. The controller32is part of one or more instances of electric circuity which may also determine the type of fluid in the fluid channel16based on processing one or more sensor signals generated by the fluid sensor10, where the one or more sensor signals indicates a fluid sensor10-measured electrical property of the fluid in the fluid channel (e.g., on basis of (“based on”) the electric resistance of the fluid). The controller32may deactivate the heater24, if an undesired fluid is determined (e.g., by the controller32based on processing one or more sensor signals generated by the fluid sensor10) to be present in the fluid channel16.

InFIG.1, the liquid storage portion18is also arranged in the housing30. However, the liquid storage portion18may be configured as a separate replaceable cartridge which may be attachable to an inlet of the pump12.

FIG.2shows an illustrative cross section of a sensor and a fluid channel according to some example embodiments.FIG.2depicts the fluid sensor10in more detail. In this regard,FIG.2shows the fluid channel16, wherein a first electrode34and a second electrode36of the fluid sensor10are arranged at the wall of the fluid channel16.

The first electrode34is arranged at the wall of the fluid channel16such that the tip of the first electrode34is in direct contact with the fluid in the fluid channel16. The second electrode36is arranged on the opposite site of the wall of the fluid channel16also in direct contact with the fluid in the fluid channel16. The first and second electrodes34,36are arranged to measure the electrical resistance of the fluid between the electrodes34,36and thus of the fluid in the fluid channel16. The electrodes34,36are supported in a carrier38for dimensional stability. The fluid sensor10has a length and width of 1 millimeter to 1 centimeter and preferably around 3 millimeter. The thickness of the fluid sensor10is 0.5 millimeter to 3 millimeter and preferably around 1.5 millimeter. The electrodes have a diameter of 0.9 millimeter. The electrodes have a length of 1 to 5 millimeter and preferably around 3 millimeter. The distance between the electrodes should be as small as possible without impeding the flow of liquid, ideally 1 millimeter or the internal diameter of the tube.

FIG.3shows an illustrative wiring diagram of a voltage divider circuit which may be employed in a sensor according to some example embodiments.FIG.3shows a voltage divider circuit which is used to generate a sensor signal indicating the electrical resistance of the fluid in the fluid channel16.

InFIG.3, a voltage divider circuit is modified in that a first resistor is replaced by the first and second electrode34,36and the fluid in the fluid channel16between the electrodes34,36. Apart thereof, the voltage divider circuit consists of the known elements of a voltage divider circuit. In more detail, a second resistor40is provided. The electrical resistance of the second resistor40is known. The electrical resistance of the second resistor can be chosen as required and is chosen suitable with respect to the electrical resistance of the liquid vapor-forming substrate. The electrical resistance of the second resistor is chosen in the range of 5 to 20 Megaohm and preferably around 12 Megaohm or approximately equal to the resistance between the two electrodes when liquid is present. Different vapor forming substrates will present different resistances therefore this may need to be specified during the design process. However most resistor values in this range will provide a significant voltage difference when liquid is present vs when it is not. The electrical resistance of the liquid vapor-forming substrate is comparable within different liquid vapor-forming substrates such as e-liquids. A known voltage is applied to the circuit. An analog-to-digital converter42is connected to the center tap of the voltage divider circuit. By using the measured voltage, the known electrical resistance of the second resistor40and the known applied voltage, the controller32, which is connected with the analog-to-digital converter42, computes the electrical resistance of the first resistor. Since the electrical resistance of the electrodes34,36is also known, the controller32thus computes the electrical resistance of the fluid in the fluid channel. At the analog-to-digital converter42, the measured voltage decreases if the electrical resistance of the fluid between the electrodes increases and vice versa.

FIG.4shows a measurement diagram of a sensor according to some example embodiments.FIG.4shows a measurement of the fluid sensor10.FIG.4depicts the voltage which is measured at the analog-to-digital converter42. The diagram shows the voltage over time. The electrical resistance of the second resistor40was set to 12 Megaohm. At first, no liquid vapor-forming substrate is present in the fluid channel16. Only air is present in the fluid channel16. Thus, the measured voltage is low, corresponding to a high electric resistance of the fluid in the fluid channel16. The electric resistance was determined to be 18 Megaohm when no substrate was present in the fluid channel16. This measurement is denoted by reference sign44. Thus, the measurement denoted by reference sign44corresponds to a sensor signal, generated by fluid sensor10, that indicates an absence of fluid in the fluid channel16, and a controller32processing said sensor signal as denoted by reference sign44might arrive at the determination that no fluid is present in the fluid channel16. As shown inFIG.4, the measured voltage at reference sign44may be below one or more particular threshold values (e.g., below one or more of the horizontal dashed lines inFIG.4). The controller32may determine, based on processing the sensor signal corresponding to the measurement denoted by reference sign44, that the measured voltage is below the one or more particular threshold values and may, as a result, determine that no fluid is present in the fluid channel16. Before the fluid channel16is fully filled with liquid vapor-forming substrate, bubbles emerge, i.e. a mixture of liquid vapor-forming substrate and air. Thus, fluctuating electrical resistance values are determined by the fluid sensor10. This measurement is denoted by reference sign46. Thus, the measurement denoted by reference sign46corresponds to a sensor signal, generated by fluid sensor10, that indicates a partial presence of fluid in the fluid channel16, and a controller32processing said sensor signal as denoted by reference sign46might arrive at the determination that at least some fluid is present in the fluid channel16. As shown inFIG.4, the measured voltage at reference sign46may be above one or more particular threshold values and also below one or more other particular threshold values (e.g., extending above and below both of the voltages represented by the horizontal dashed lines inFIG.4). The controller32may determine, based on processing the sensor signal corresponding to the measurement denoted by reference sign46, that the measured voltage extends below one or more particular threshold values and also above one or more particular threshold values (e.g., one or more other particular threshold values) and may, as a result, determine that at least some fluid is present in the fluid channel16. When the fluid channel16is fully filled with liquid vapor-forming substrate, the measured voltage is high, corresponding to a comparatively low electric resistance of the liquid vapor-forming substrate in the fluid channel16(reference sign48). The electric resistance was determined to be 10 Megaohm when the fluid channel16was fully charged with liquid vapor-forming substrate. Thus, the measurement denoted by reference sign48corresponds to a sensor signal, generated by fluid sensor10, that indicates a full presence of fluid in the fluid channel16, and a controller32processing said sensor signal as denoted by reference sign48might arrive at the determination that fluid is present in the fluid channel16. As shown inFIG.4, the measured voltage at reference sign48may be above one or more particular threshold values (e.g., above one or more of the horizontal dashed lines inFIG.4). The controller32may determine, based on processing the sensor signal corresponding to the measurement denoted by reference sign48, that the measured voltage is above the one or more particular threshold values and may, as a result, determine that fluid is present in the fluid channel16. The same principle applies when—at first—liquid vapor-forming substrate is present in the fluid channel and—subsequently—air is present in the fluid channel. In this case, liquid vapor-forming substrate will be followed by bubbles and eventually by air.

FIG.5shows a measurement diagram of a sensor according to some example embodiments.FIG.5is a measurement of the fluid sensor10with other parameters than the parameters used inFIG.4. In the measurement as used in FIG.5, the electrical resistance of the second resistor46was set to 5.6 Megaohm. The measurement shown inFIG.5may also be the sensor signal generated by the fluid sensor10, where the sensor signal indicates the measurement. The measurement was conducted with different fluids in the fluid channel16. The fluids used were water, a fluid with glycerol, denoted 80 PG/20 VG, and a further fluid with higher glycerol content, denoted 20 PG/80 VG. As shown inFIG.5, measurements (sensor signals)50correspond to measurements of water in the fluid channel16by the fluid sensor10, measurements (sensor signals)52correspond to measurements of the fluid with glycerol (80 PG/20 VG) in the fluid channel16by the fluid sensor10, and measurements (sensor signals)54correspond to measurements of the fluid with higher glycerol content (20 PG/80 VG) in the fluid channel16by the fluid sensor10. Between measurements of the different fluids, the fluid channel16was cleaned using isopropanol and water to prevent contamination of the fluid channel16. The measurements were delayed until the respective fluids50,52,54had filed the fluid channel16and a stable measurement signal could be obtained.FIG.5shows the measured resistance against the time.

The measurement depicted inFIG.5shows that the three sets of sensor signals50,52,54generated by the fluid sensor10based on measuring the different fluids, respectively, could clearly be distinguished from one another based upon the measured electrical resistance. It has been observed that the measured electrical resistance increased over time. Without being bound to any theory, it is believed that this increase was a result of polarization of the fluids measured with measurements50,52,54. Particularly the fluid with high glycerol content, measured in measurements54, was prone to polarization, since glycerol does not dissociate in water and so the fluid measured in measurements54contained a low initial ion count resulting in faster and more pronounced polarization. To avoid an increase of the measured electrical resistance over time, alternating current could be used for measuring the electrical resistance.

The example embodiments described above illustrate but are not limiting. In view of the above discussed example embodiments, some example embodiments consistent with the above example embodiments will now be apparent to one of ordinary skill in the art.