Patent Publication Number: US-2023149229-A1

Title: Personal hygiene device for detecting a fluid

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional of U.S. application Ser. No. 16/106,463 filed Aug. 21, 2018, the disclosures of all of which are hereby incorporated by reference as if set forth in their entirety herein. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to a personal hygiene device configured to detect the presence of fluid, and in particular to a personal hygiene device comprising a capacitance sensor. 
     BACKGROUND 
     Many types of personal hygiene devices (e.g., products) exist in the market today. Examples of such personal hygiene devices include tampons, bed pads, disposable diapers, and disposable sanitary napkins. In particular, feminine hygiene products may be used during a woman&#39;s menstrual cycle. Women may experience various menstrual flows over the course of each cycle, with some days having a heavier menstrual flow than other days. Because of this variance in flow, it is sometimes difficult to accurately predict and judge when a hygiene product should be used or replaced. This often causes personal hygiene products to become oversaturated leading to potential accidents or overflow beyond the absorbent area of the product. Furthermore, continued use of an oversaturated hygiene product may lead to negative health side-effects, such as toxic shock syndrome and other infections. 
     Many women manually track or monitor their menstrual cycle for predictability to avoid the unexpected start of menstruation in the absence of a personal hygiene product or accidents of the sort discussed above. There are over two hundred smart device applications available to monitor menstruation manually. Users enter data into the application on a smart device, for example a smart phone or other hand-held device, and the application generates data predicting, for example, menstrual start day, flow pattern, and length of menstruation. Many of these smart device applications issue alerts when menstruation is expected to start and end. All available devices, however, rely on data based on the subjective and manual entry of the user and may not reliably meet the primary needs most female hygiene product users have; namely, predictability and reliability. None of these applications are able to actively monitor the active absorption capacity of a personal hygiene product while a user is wearing or using it. 
     In addition to the need for predictability and reliability in use of a personal hygiene product, a personal hygiene product is situated either proximate to or inserted into the body and as a result is able to collect data about patterns of discharge and biometrics in a way that a manual-entry application is unable to capture. This data is beneficial, to avoid social embarrassment, and also for a user&#39;s overall health, for example, to provide accurate data to a physician or to alert the user if there are disruptions in normal patterns of bodily fluid discharge. 
     For example, menstrual issues and patterns of discharge are one of the most common reasons for a woman to see a doctor. Generally, a doctor&#39;s first response will be for the woman to keep a “menstrual diary” as a record of the period dates, length of periods, flow, etc. Menstruation that departs from a normal monthly cycle, such as lasting longer or shorter than usual or not occurring at all, may indicate an underlying health issue. For example, abnormally long menstrual bleeding may indicate irregularities such as polyps, fibroids, cancer or infection within the uterus or cervix. A number of conditions may be revealed from menstrual flow data; including dysmenorrhea (painful periods); oligomennorhoea (irregular periods); amenorrhea (lack of periods); and menorrhagia (heavy periods). 
     The location of a personal hygiene product may enable it to gather internal and external biometric data such as temperature or pH. Menstruation, for example, also includes discharge with biometric information. Monthly menstruation involves a process in which the uterus sheds the endometrium to allow a new lining to replace it. Menstrual fluid comprises uterine blood, meaning the endometrial tissue, vaginal secretions, and cervical fluids. Menstrual fluid also includes information through hormones such as estrogen and progesterone and enzymes related to pregnancy such as hydrolytic enzymes and lysosomes. 
     In the home health setting, for example, individuals receive periodic check-ups by home health staff ranging from multiple times daily to weekly. Isolated visits may not capture or accurately give warning if an individual has additional health issues if those issues do not present during a check-up. The valuable biometrics that may be gleamed from a personal hygiene product would accurately convey extensive data that if available electronically to a health professional would provide a more accurate and holistic understanding of the patient&#39;s health. Additionally, a personal hygiene product with a sensor system may facilitate remote monitoring either by a health care professional or family member. 
     The proper combination of a personal hygiene product incorporated with a sensor system capable of interfacing with a smart hand-held electronic device would meet the ultimate needs of personal hygiene product consumers. The sensor system needs to be biocompatible and comprise an array capable of wireless communication. Accordingly, there exists a need for providing a personal hygiene product capable of gathering, processing, and communicating data about the product&#39;s absorbent capacity and individual user&#39;s bodily fluid discharge to the smart hand-held electronic device of a user. There are also exists a need for an individual user to be able to interface with the data once communicated to the smart hand-held electronic device. 
     SUMMARY 
     A personal hygiene device according to the present invention may have a main body with an absorbent material configured to absorb a fluid, a sensor disposed within the main body, and a controller configured to communicate with the sensor. The sensor may be or comprise a conductor and an insulator disposed adjacent at least a portion of the conductor. The sensor may be or comprise a capacitive sensor and/or may comprise a pair of insulated conductors spaced from each other. The sensor may be configured to detect a first electrical value and/or a second electrical value that is different from the first electrical value. Such electrical values may be or comprise electric field strength, permittivity, and/or a capacitance, or other electrical values. The sensor may be configured to transmit a signal to the controller indicative of the detected electrical value. 
     In some aspects, the conductor may be or comprise a plurality of conductors (e.g., a pair of conductors), for example, at least a pair of linear conductors, each of which are substantially parallel to one another. A capacitive sensor for detecting the presence of a fluid according to the present invention may comprise the plurality of conductors and an insulating material positioned adjacent each conductor in the plurality of conductors. At least a portion of the insulating material is disposed between at least two of the plurality of conductors. The plurality of conductors may be configured to have a first capacitance value when fluid is not present within the sensor and a second capacitance value when fluid is present in the sensor. The sensor may be configured to detect an absolute measurement of an electrical characteristic and/or a relative measurement such as change from a first capacitance to a second capacitance. Such measurements may be analyzed and may be communicated to a user of the personal hygiene device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present application is further understood when read in conjunction with the appended drawings. For the purpose of illustrating the subject matter, there are shown in the drawings exemplary aspects of the subject matter; however, the presently disclosed subject matter is not limited to the specific methods, devices, and systems disclosed. Furthermore, the drawings are not necessarily drawn to scale. In the drawings: 
         FIG.  1    illustrates a side cross-sectional view of a personal hygiene device according to an aspect of the present disclosure; 
         FIG.  2    illustrates a top cross-sectional view of the aspect illustrated in  FIG.  1   ; 
         FIG.  3    illustrates a side cross-sectional view of a personal hygiene device according to another aspect of the present disclosure; 
         FIG.  4    illustrates a top cross-sectional view of the aspect illustrated in  FIG.  3   ; 
         FIG.  5    illustrates a top cross-sectional view of a personal hygiene device according to yet another aspect of the present disclosure; 
         FIG.  6    illustrates a top cross-sectional view of a personal hygiene device according to yet another aspect of the present disclosure; 
         FIG.  7    illustrates a side perspective view of a personal hygiene device physically connected to a controller according to an aspect of the present disclosure; 
         FIG.  8    illustrates a side perspective view of a personal hygiene device wirelessly connected to a controller according to another aspect of the present disclosure; 
         FIG.  9    illustrates a front planar view of a sensor according to an aspect of the present disclosure; 
         FIG.  10    illustrates a top planar view of the sensor illustrated in  FIG.  9   ; 
         FIG.  11    illustrates a front planar view of a sensor according to another aspect of the present disclosure; 
         FIG.  12    illustrates a top planar view of the sensor illustrated in  FIG.  11   ; 
         FIG.  13    illustrates a top cross-sectional view of a personal hygiene device according to another aspect of the present disclosure; 
         FIG.  14    illustrates a top cross-sectional view of a personal hygiene device according to yet another aspect of the present disclosure; 
         FIG.  15    illustrates a side cross-sectional view of a personal hygiene device according to yet another aspect of the present disclosure; 
         FIG.  16    illustrates a side cross-sectional view of a personal hygiene device according to yet another aspect of the present disclosure; 
         FIG.  17    illustrates a side cross-sectional view of a personal hygiene device according to yet another aspect of the present disclosure; 
         FIG.  18    illustrates an isometric view of a personal hygiene device according to yet another aspect of the present disclosure; 
         FIG.  19    illustrates a top cross-sectional view of a personal hygiene device according to yet another aspect of the present disclosure; and 
         FIG.  20    illustrates a side cross-sectional view of the personal hygiene device of  FIG.  19   . 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE ASPECTS 
     Aspects of the disclosure will now be described in detail with reference to the drawings, wherein like reference numbers refer to like elements throughout, unless specified otherwise. Certain terminology is used in the following description for convenience only and is not limiting. 
     A device (e.g., hygiene product) comprising a sensor system capable of interface with a smart, hand-held, electronic device is disclosed in this application. In the following sections, detailed descriptions of various aspects are described. The descriptions of various aspects are illustrative aspects, and various modifications and alterations may be apparent to those skilled in the art. Therefore, the exemplary aspects do not limit the scope of this application. The sensor system is designed for use in or adjacent to the body of a living organism. 
     The device may be optimized to accurately detect a signal. A sensor of the device may be optimized to maximize a change in capacitance on exposure to a fluid. This optimization may be done by altering the cross section of one or more conductors of the sensor so the electric field between the one or more conductors encounters less of the insulator (fixed) and more of the fluid (variable). For example, the cross section may be formed with an elliptical shape. To fully maximize the change in capacitance, the one or more conductors may be surrounded by very thin and/or sharp insulation, such as a flat ribbon cable. This shape is not desired due to comfort concerns. An optimized cross section may be based on a balance between capacitance, comfort, cost, and/or the like. An optimized cross section may be implemented by using an elliptical extrusion die when producing insulated ribbon cable. Treatment, for example head and rolling, may be applied to classical ribbon cable having circular cross sections. 
     The device may be optimized by using a separator between the one or more conductors of the sensor. A portion of the separator may be implemented with a hydrogel or similar fluid-permeable material. The separator may be configured to provide a controlled separation between the one or more conductors. The separator may be configured to prevent shorting. The separator may be configured to establish a baseline capacitance (e.g., a dry capacitance). The insulator (e.g., which may be impermeable to fluids) may be at least partially removed (e.g., exposing the conductors) between the conductors. The portion of the insulator that is removed may be replaced with a permeable material such as a hydrogel. In some scenarios the insulator may be formed with a gap or with a portion comprising permeable material. At least a portion of the remaining insulator may provide an electrical open. The insulator and hydrogel may both act to mechanically separate the conductors. As the sensor is exposed to fluid, fluid can now permeate directly between the conductors. This configuration may have an increased change in capacitance on exposure to fluid (e.g., resulting in improved accuracy). The sensor may be formed using a co-extrusion process. 
     The device may further be optimized by applying a surface-treatment to the insulator and/or separator. The surface treatment may increase uptake of fluid (e.g., resulting in a faster and more accurate sensing for the user). The surface treatment may also be applied to a tampon comprising the device. The fibrous filler in a tampon, especially under heavy compression, may fill the space outside the sensor insulation and act to carry fluid close to the conductors. Surface treatment of the fibers and/or sensor insulation may improve sensor speed and accuracy. This treatment may be especially important if a particular insulator is optimized for cost, abrasion resistance, dielectric constant, etc. which could be at odds with surface energy. 
     In certain aspects, the sensor system of the present disclosure may be or comprise a capacitance sensor. An exemplary capacitance sensor may comprise at least a pair of linear conductive leads spaced from each other and configured to generate an electric field between each other when electric potential is applied across the conductive leads. The conductive leads may comprise one or more of a conductive wire, a conductive thread, or a conductive yarn. The conductive yarn may comprise a yarn that has been treated (e.g., covered) with a conductive material. The conductive thread may comprise a thread that has been treated (e.g., covered with a conductive material). 
     The capacitance sensor may comprise an insulator. The insulator may be one or more of hydrophilic, hydrophobic, omniphilic, omnophobic, oleophilic, or oleophobic. For example, the insulator may be treated to cause a surface of the insulator to be one or more of hydrophilic, hydrophobic, omniphilic, omnophobic, oleophilic, or oleophobic. The insulator may be disposed between an absorbent material and at least a portion of each of the conductive leads. As an example, an electrically insulative material may be disposed about at least a portion of each of the linear conductive leads. As such, the insulative material may be disposed between each of the linear conductive leads. The insulative material may also insulate the linear conductive leads from the absorbent material. Accordingly, when electrical current is applied to one or more of the linear conductive leads, an electric field is generated between the linear conductive leads. The linear conductive leads and the electrical current are configured such that at least a portion of the generated electric field passes through the absorbent material. As a fluid level (e.g., saturation) of the portion of the absorbent material in the generated electric field changes, electrical characteristics (e.g., capacitance) of the dielectric or other materials in the field may change. Such a change may be measured and may be indicative of the fluid level of the personal hygiene device incorporating the sensor system. As an example, the sensor system may be configured to detect a first capacitance value and a second capacitance value that is different from the first capacitance value. 
     A controller may be integrated with or configured to communicate with the sensor system (e.g., capacitance sensor). As measurement of electrical characteristics of the capacitance sensor is made, a signal may be transmitted to the controller. The signal may be indicative of one or more of a first capacitance value and a second capacitance value. As described herein, the first capacitance value and the second capacitance value may be dependent upon the presence of a fluid within the electric field between the linear conductive leads when electric current is applied to one or more of the linear conductive leads. The controller may be configured to analyze the received signal and may determine an associated fluid level (e.g., saturation). Such determination may be an absolute or relative determination. Moreover, the controller may communicate the associated fluid level to a user of the device, for example, via a user interface. 
     Referring to  FIGS.  1  and  2   , a personal hygiene device  100  comprises a main body  110  (e.g., substrate, housing, etc.) with a sensor  120 ,  220  disposed adjacent, embedded within, or attached thereto. The personal hygiene device  100  may be or comprise a tampon configured for insertion into the body. The personal hygiene device  100  may also comprise a bed pad, diaper, sanitary napkin, undergarment liner, surgical dressing, or another personal hygiene item configured to absorb liquid. 
     The main body  110  may be formed from or may comprise an absorbent material  112 . The absorbent material  112  may be configured to absorb liquid that comes in contact with the material, for example, bodily fluids, and specifically menstrual fluids. The main body  110  may comprise one absorbent material  112 , or it may include a combination of materials. The absorbent material  112  may have an inner core and an outer core (not shown) that include different compositions of material. In some aspects, the absorbent material  112  may include cotton, rayon, polyester, polypropylene, polyethylene, or another suitable absorbent material. The personal hygiene device of some aspects may be designed to directly contact with, or insert into, the human body, and the absorbent material of such aspects should be biocompatible with the human body so as to avoid an adverse reaction upon contact with or insertion therein. 
     With further reference to  FIGS.  1  and  2   , the main body  110  has a proximal end  114  and a distal end  116 . In some aspects, the main body  110  may be substantially cylindrical, extending from the proximal end  114  to the distal end  116 . It will be appreciated by those skilled in the art that the exact measurements of a personal hygiene device may vary depending on application and individual needs of users. In some non-limiting aspects, the main body  110  may be less than three inches in length. However, other implementations and sizes may be used. In some aspects, the absorbent material  112  within main body  110  may be configured to absorb liquid and expand accordingly. Once again, those skilled in the art will appreciate that the absorbance capacity may vary amongst aspects depending on application and individual needs of the user, for example, the duration and volume of a user&#39;s menstrual cycle. Some aspects absorb lower amounts of liquid, for example less than six grams. Other aspects may be configured to absorb higher quantities of liquid, such as up to six grams, up to nine grams, up to twelve grams, up to fifteen grams, or up to eighteen grams of liquid. It will be understood that some aspects may be configured to absorb greater than eighteen grams of liquid, and the above volumes should not be construed as limiting the disclosure. 
     The personal hygiene device  100  may comprise a sensor system such as sensor  120 . The sensor  120 ,  220  may be fixedly secured to the main body  110 , or it may be removably attached to the main body  110 . In some aspects, the sensor  120 ,  220  may be embedded within the absorbent material  112 . Alternatively, the sensor  120 ,  220  may be positioned at or proximal to the exterior surface  111  of the main body  110 . Referring to  FIGS.  1  and  2   , the sensor  120 ,  220  is fully encapsulated within the absorbent material  112 . In some aspects, the sensor  120 ,  220  may be partially encapsulated within the absorbent material  112 . The sensor  120 ,  220  may extend substantially the length of the main body  110 , or it may be shorter than the main body  110 . 
     The sensor  120 ,  220  may be positioned approximately in the center of the main body  110  when viewed along an axial direction extending from the proximal end  114  to the distal end  116 . In some aspects, the sensor  120 ,  220  may be closer to the exterior surface  111  of the main body  110  than to the center as shown in the illustrative aspect of  FIG.  14   . In some aspects, the personal hygiene device  100  may include a plurality of sensors  120  ( FIG.  2    sensor  220 ). According to  FIG.  14   , each of the sensors  120  ( FIG.  2    sensor  220 ) may be positioned radially around the center of the main body  110 . Referring to  FIG.  17   , multiple sensors  120  ( FIG.  2    sensor  220 ) may be positioned throughout the main body  110  such that at least some of the sensors  120  are disposed at different distances from the proximal end  114 . In some aspects, the personal hygiene device  100  may include two, three, four, five, six, seven, or eight sensors  120  ( FIG.  2    sensor  220 ). The quantity of sensors is not limiting, and a personal hygiene device  100  may include a different suitable quantity of sensors. The sensors  120 ,  220  may have the same dimensions and parameters, or they may be different. In some aspects, the plurality of sensors  120 ,  220  may include sensors of different sensing types. For example, some personal hygiene devices may include a sensor that detects moisture, a sensor that detects consistency of a liquid (e.g., the type of liquid), the amount of absorbed liquid, a physical change in size of the device (e.g., expansion of the absorbent material  112  after absorption of liquid), or another sensing parameter that may be advantageous to include in an aspect of a personal hygiene device. 
     In another aspect, the sensor  120 ,  220  may be a capacitive sensor and include a capacitor. The sensor may include a conductor that contacts an insulating material  124 . In some aspects, sensor  120 ,  220  includes a plurality of conductors. Referring to  FIGS.  1  and  2   , the sensor  120 ,  220  may have a first conductor  122   a  and a second conductor  122   b , each conductor having a length and extending approximately parallel to the other conductor. The first conductor  122   a  and the second conductor  122   b  may be configured to have a voltage or potential difference therebetween. As such, the sensor  120 ,  220  may be a capacitive sensor in that the first conductor  122   a  and the second conductor  122   b  operate as a capacitor. As such, the sensor  120 ,  220  (comprising the first conductor  122   a  and the second conductor  122   b ) may be configured to detect the capacitance, change in the capacitance, and/or change in potential difference based on the detected environment of the first conductor  122   a  and the second conductor  122   b.    
     The sensor  120 ,  220  may include insulating material  124  configured to insulate at least a portion of the conductor from the absorbent material  112  of the personal hygiene device  100 . It will be understood by a person skilled in the art that an insulating material may include many different materials having varying conductive properties. The insulating material  124  may include plastics, rubbers, fluoropolymers, naturally-occurring materials, or another suitable material having insulating properties. The insulating material  124  may include or may be formed from thermoplastic urethane (TPU). Additionally, or alternatively, suitable materials may include, but are not limited to, polyvinyl chloride, polyethylene, polypropylene, polyurethane, thermoplastic rubber, neoprene, styrene butadiene rubber, silicone, fiberglass, ethylene propylene rubber, ethylene propylene diene monomer, polytetrafluoroethylene, thermoplastic elastomer, or a combination of the preceding. 
     Insulating material  124  may have various thicknesses. In some illustrative aspects, for example, the thickness may be less than about 1 mm. In further aspects, the thickness may be less than 0.3 mm, or may be between 0.1 mm and 1 mm in thickness. 
     In some aspects, the insulating material  124  may also include a coating (not shown) on its surface. The coating may include various materials that improve sensor resilience, speed, and/or accuracy. A non-limiting example of a suitable coating includes thermoplastic polyurethane (TPU). Other coatings may be used to configure wettability and other physical and electrical characteristics. As a further example, the insulating material  124  may be formed from the TPU with a loading of up to 100 percent by weight of the total weight of the insulating material  124 . 
     Various embodiments of sensors are described herein, and it will be understood that each of these embodiments may share certain similarities with other embodiments. In some aspects, the entire conductor is encapsulated within the insulating material  124 . Referring to  FIGS.  3 - 5   , in some aspects, a dielectric gap  123  is defined by the space between the first conductor  122   a  and the second conductor  122   b . As shown in the illustrative embodiment of  FIGS.  3 - 4   , the dielectric gap  123  of sensor  220  may have disposed within it a suitable dielectric material  130  (e.g., air, hydrogel, etc.). The dielectric material  130  may be disposed at least partially between the first conductor  122   a  and the second conductor  122   b  and may exhibit insulating properties. 
     Referring to  FIGS.  3 - 6    in some aspects, the dielectric material  130  within the dielectric gap  123  may comprise one material or a plurality of suitable materials. In some aspects, the dielectric material  130  may include insulating material  124 . In a further aspect, the dielectric material  130  is entirely comprised of insulating material  124 . Alternatively, the dielectric material  130  may comprise a different composition and exclude the insulating material  124  entirely. 
     Referring to  FIG.  4   , the sensor  220  has a dielectric material  130  (e.g., in the dielectric gap  123  shown in  FIG.  2   ) disposed between the first conductor  122   a  and the second conductor  122   b . The dielectric material  130  may be a semi-permeable material such that liquid can pass through it. Dielectric material  130  may comprise a porous material that exhibits hydrophilic properties. In some aspects, the dielectric material  130  includes a hydrogel. The hydrogel may be composed of biocompatible materials having varying dielectric properties and relative permittivity. As shown in  FIGS.  4 - 5   , the dielectric material may be formed to have different shapes and dimensions. As shown in the embodiment of  FIG.  4   , the sensor  220  may have dielectric material  130  that generally complements the shape of the insulating material  124  (e.g., having a circular cross section). As shown in the embodiment of  FIG.  5   , a sensor  320  may include dielectric material  130  that partially surrounds or overlaps the insulating material  124 . 
     For some aspects of a capacitive sensor, it may be advantageous to maintain the width of the dielectric gap  123  approximately constant. As such, it may be necessary for the dielectric material  130  to be rigid enough to support the structure of the sensor  220  and to withstand reasonably-expected compressive, tensile, and shear forces acting on the sensor during normal use. 
     The sensor  120 ,  220  may have an approximately circular cross section when looking in an axial direction extending from the proximal end  114  to the distal end  116  of the main body  110 . In some aspects, the sensor  120 ,  220  may include a plurality of cross sections corresponding to a plurality of conductors. Referring to  FIG.  2   , a sensor having two conductors, a first conductor  122   a  and a second conductor  122   b , may have two circular cross sections approximately adjacent one another, each of the two cross sections corresponding to the first and second conductors, respectively. In some aspects, as depicted in the illustrative embodiment of  FIG.  6   , a sensor  420  may have a non-circular oval cross section. In further aspects, the sensor may have a substantially rectangular cross section. It will be understood that the sensor cross section is not limiting, and the present disclosure encompasses other shapes that would result in a suitable sensor. 
     Referring now to  FIGS.  9 - 12   , a capacitive sensor  120  or  220  may generate an electric field  140 . Properties of the electric field  140  and the capacitance of the sensor  120  are affected by numerous parameters, for example the surface area of conductors  122   a  and  122   b , the distance between conductors  122   a  and  122   b , and the material disposed within the dielectric gap  123 . As such, when one or more factors affecting capacitance are changed, such a change may be detected and may be indicative of an environmental change such as a fluid within the electric field of the capacitive sensor  120  or  220 . 
     In some aspects, it may be advantageous to maintain as short a distance as possible between conductors  122   a  and  122   b  to improve capacitance and sensor accuracy. Although the sensor is scalable, it will be understood that the personal hygiene product should not be sized such that it is unreasonably large or small for any of its intended uses. According to some aspects, the insulating material  124  may be a thin layer, such that the separation between the conductor  122  and the absorbent material  112  is minimal. Moreover, the amount or percentage of open (air or fixed dielectric) surface area between the conductors  122   a  and  122   b  (as opposed having a fluid disposed there between) may facilitate a detection of the dielectric constant change when a fluid enters the system. For example, k=1 for air, but k˜50 for a fluid. 
     The capacitance of a parallel plate capacitor may be calculated with the following formula: 
     
       
         
           
             
               C 
               = 
               
                 
                   
                     
                       k 
                       ⁢ 
                       ε 
                     
                     0 
                   
                   ⁢ 
                   A 
                 
                 d 
               
             
             , 
           
         
       
     
     where C is the capacitance, k is the relative permittivity of the material between the conductors, A is the area of the conductors, d is the distance between the conductors, and ϵ 0  is a constant corresponding to the permittivity of free space in a vacuum (8.8542×10 12  F/m). A parallel plate model is presented herein to explain concepts, but one skilled in the art will appreciate that the capacitance of an actual system will be more accurately described with complex models. 
     In some aspects, the area of the conductors A and the distance d between conductors  122   a  and  122   b  (corresponding to the dielectric gap  123 ) may be kept substantially constant. The dielectric layer  130  disposed in the dielectric gap  123  between conductors  122   a  and  122   b  may be configured to have a variable composition such that its relative permittivity k changes. In some aspects, the dielectric material  130  has a first relative permittivity value when the dielectric material does not include a liquid and a second relative permittivity value when the dielectric material includes a liquid. The physical and chemical composition of the dielectric material having liquid may be different from that of the dielectric material lacking liquid, and so the first and second relative permittivity values may be different as well. According to some aspects, the dielectric material that includes liquid will have a higher relative permittivity k than the same dielectric material that does not include liquid. In such aspects, the capacitance C may be greater for dielectric material having liquid than for dielectric material lacking liquid. 
     In operation, if a liquid becomes disposed at least partially within the dielectric gap  123 , the capacitance of the sensor  120  changes. This change may be detected by a circuit in communication with the sensor  120  (or the sensor  120 ) and communicated to an external device. 
     In some aspects, the personal hygiene device  100  may be connected to a controller  150 . The controller  150  may receive data from the sensor  120 . In some cases, the controller  150  may carry out a calculation or to further relay information to another device. Controller  150  may be a printed circuit board or a computing device, such as, but not limited to, a proprietary interface device, a cellular phone, a wrist watch, an electronic bracelet, or a personal computer. The controller  150  may be configured to provide a user with information corresponding to the sensor  120 . Information may include, for example, detection of liquid within the sensor, the quantity of liquid detected, the consistency of the liquid, and the duration of presence of liquid within the personal hygiene device. Referring to  FIGS.  7 - 8   , the controller  150  may be connected through a physical wire  152  to the personal hygiene device  100 . Alternatively, it may be connected through wireless communication  154 . Wireless communication may include, but is not limited to, Wi-Fi, Bluetooth, ANT, radio frequency, infrared, near-field communication, or another suitable wireless interface. Controller  150  may be physically attached to the personal hygiene device  100 , for example disposed on the main body  110  or within the absorbent material  112  of the main body  110 . Alternatively, controller  150  may be separate from the main body  110 . 
     The controller  150  may be in communication with a user device such as smart phones, personal computers, tablets, servers, cloud services, and the like. In some aspects, the sensor system such as sensor  120  is capable of wireless communication with a user device via the controller  150  or a transceiver. The user device may comprise a software application, which may comprise, for example, an interface that quantifies the user-based data received and generates a visual representation of quantified data for the user, including but not limited to, for example, generation of a chart, display, or alert for the user. 
     In some aspects, the software application may be able to provide the user with visual representation of the level of absorption by the personal hygiene product based on liquid absorption capacity and actual body fluid absorption. In some aspects, the software application may be able to provide the user with time frame for absorbency and anticipated saturation points. In some aspects, the software application may generate an alert signal to the user if saturation of the personal hygiene product is impending or reached. In some aspects, the software application may generate a visual representation of the quantified data, including but not limited to, for example, the user&#39;s rate of bodily fluid discharge or historical data of bodily fluid discharge. 
     In some aspects, the software application may be capable of accumulating data generated over time from use of multiple personal hygiene products. In some aspects, the software application may be able to generate a graphic, chart, or other interface to illustrate a baseline for the body fluid discharge based on the historical data. In some aspects, the software application may be able to generate predictive analytics and communicate that information to a user. Such information may allow the user to anticipate start and end dates, for example, if the personal hygiene product with a sensor system is used for a menstruation cycle. Such information may allow the user to understand the course of a cycle, including days or time periods of heavier or lighter flow. 
     In some aspects, a software application may generate information on a consumable usage rate for the user, predicting how many personal hygiene products are needed, including but not limited to, for example, per day, per week, or per cycle. In some aspects, a software application may generate a reminder or warning for a user to purchase personal hygiene products, including but not limited to, for example, when a start date for menstruation has been identified. In some aspects, a software application may provide the user an order quantity estimation based on historical data of the user&#39;s bodily fluid discharge. In some aspects, the interface of the software application may provide a direct link to an internet-based consumer service where a user may order and purchase additional personal hygiene products for direct delivery. In some aspects, the software application may be capable of automatic direct order placement based on consumable usage rate for delivery direct to user. The software application may facilitate purchase of additional personal hygiene products. The software application may connect the user to internet-based consumer services. 
     In some aspects, the personal hygiene device  100  may be configured to connect to a power source  160 . The power source  160  may provide power to the sensor  120 , the controller  150 , a wired or wireless communication  152  or  154 , or another element associated with the device. The power source  160  may be coupled to the main body  110 . In some aspects, power source  160  may be a battery. 
     The sensor  120  may be configured to have an “on” state and an “off” state. In the “on” state, sensor  120  may receive a charge within its conductors  122  and actively communicate with the controller  150 . In the “off” state, the conductors  122  are not charged, and data is not communicated to the controller  150 . In some aspects, the sensor  120  may be configured to switch from the “off” state to the “on” state when it is removed from a protective wrapping, such as a shipping container or retail packaging. In another aspect, the sensor  120  may be manually switched from the “off” state to the “on” state by the user. The user may turn the sensor on via a physical switch or via a command within the controller  150 . In a further aspect, sensor  120  may be switched to an “on” state automatically when an external condition is met, for example, when the personal hygiene device is in physical proximity to the controller  150 . 
     The sensor  120  may be configured without binary “on” and “off” states. For example, the sensor  120  may have a continuum of states. The sensor  120  may be a passive component. The sensor  120  may generate signals and/or changes in states based on movement of the fluid around the sensor. The sensor  120  may comprise capacitor having a capacitance that fluctuates based on the fluid around the sensor  120 . Changes (e.g., changes in capacitance) in sensor  120  may be measured by the controller  150 . In some scenarios, the sensor  120  may be configured to perform measurements and/or signal conditioning before sending signals or fluctuations in signals to the controller  150 . For example, the sensor  120  may be configured to filter out signals below a threshold change, noise, and/or the like. 
       FIGS.  13 - 20    depict additional, non-limiting alternative aspects of this disclosure.  FIG.  13    shows a personal hygiene device  500  having a plurality of sensors  120 . As shown in the aspect of  FIG.  13   , sensors  120  may be disposed near the center of the main body  110  such that the conductors  122   a ,  122   b  extend in a first direction and then loop back in a second opposite direction, for example, to maximize conductive surface area. Although  FIG.  13    illustrates a cross section of the device  500 , it is understood that the conductors  122   a ,  122   b  are shown extending into and out of the page. In some aspects, the sensor  120  may be positioned close to the surface of the main body  110 . As shown in the illustrative aspect of  FIG.  14   , a personal hygiene device  600  includes sensors  120   a ,  120   b ,  120   c , and  120   d  that are positioned radially around the centerline of main body  110 . As described in reference to  FIG.  13   , the sensors  120   a - d , may comprise a pair of conductors  122   a ,  122   b  that are looped to extend into and out of the page, but are formed form a continuous thread or wire. Alternatively, the conductors  120   a - d  may comprise distinct conductors, each configured to sense a portion of the device  500 . 
       FIGS.  15 - 17    depict aspects having various sensor configurations within the main body  110 . In some aspects, as illustrated in  FIG.  15   , a personal hygiene device  700  may have a sensor  120  that is positioned within the main body  110  such that the sensor  120  is closer to the proximal end  114  than to the distal end  116 . Alternatively, the opposite aspect is also possible where the sensor  120  is closer to the distal end  116  than to the proximal end  114 .  FIG.  16    depicts a personal hygiene device  800  that includes one sensor  120  that extends from proximal end  114  to distal end  116  substantially through the entire length of the main body  110 . Additionally, the sensor  120  of device  800  may loop back and extend from the distal end  116  toward the proximal end  114  in a “U-shaped” configuration. 
     Referring to  FIG.  17   , a personal hygiene device  900  may include multiple sensors  120  disposed within the personal hygiene device  100 . Although each consecutive sensor depicted in  FIG.  17    is illustrated as separate from the preceding sensor by an approximately equal distance, it will be understood that the distance between individual sensors may vary. 
       FIG.  18    depicts an aspect of the present disclosure in which the personal hygiene device is a sanitary napkin  1000 . The sanitary napkin  1000  may comprise one or more layers. The one or more layers may comprise an absorbent material, such as absorbent fibers. The sensor  120  may be disposed within and/or between the one or more layers. The sensor  120  may be located in only a portion of the sanitary napkin  1000 . In other implementations, the sensor  120  may extend along a length and/or width of the sanitary napkin  100 . The one or more layers of the sanitary napkin may be surface treated as described further herein. 
     In some aspects, as illustrated in  FIG.  19   , a personal hygiene device  1100  may have a sensor  120  that is disposed within the main body  110 . The sensor  120  may comprise generally parallel conductors  122   a ,  122   b  such as wires or conductive threads comprising a non-conductive core and conductive coating. The configuration of the conductors  122   a ,  122   b  may be operative as a capacitor extending along a length of the device  1100 .  FIG.  20    depicts the personal hygiene device  1100  showing the sensor  120  (e.g., conductors  122   a ,  122   b ) of device  1100  looping back in a “U-shaped” configuration. 
     Aspects of the personal hygiene device as described herein offer a number of advantages over existing products. Some aspects provide active monitoring of absorption capacity of the personal hygiene product while a user is wearing or using it. The device may collect data about menstruation patterns, as well as other biometrics. Collected data may be used to instruct the user to adjust or replace the hygiene device so as to avoid oversaturation of the absorbent material and prevent unexpected outflow. This may help decrease the risk of associated health problems, such as infections, as well as to avoid unpleasant social interactions or embarrassment. Some aspects allow for collection of multiple variables, which can be used to predict likely health scenarios, as well as to provide data to a physician if necessary. Continuous monitoring may also be helpful in reminding a user to employ a new hygiene device even if the user forgets to do so, and the collected data may be used to alert the user in case of disruptions to normal or expected cycle patterns. 
     The term “plurality,” as used herein, means more than one. The singular forms “a,” “an,” and “the” include the plural reference, and reference to a particular numerical value includes at least that particular value, unless the context clearly indicates otherwise. Thus, for example, a reference to “a material” is a reference to at least one of such materials and equivalents thereof known to those skilled in the art, and so forth. 
     The transitional terms “comprising,” “consisting essentially of,” and “consisting” are intended to connote their generally accepted meanings in the patent vernacular; that is, (i) “comprising,” which is synonymous with “including,” “containing,” or “characterized by,” is inclusive or open-ended and does not exclude additional, unrecited elements or method steps; (ii) “consisting of” excludes any element, step, or ingredient not specified in the claim; and (iii) “consisting essentially of” limits the scope of a claim to the specified materials or steps “and those that do not materially affect the basic and novel characteristics” of the claimed invention. Aspects described in terms of the phrase “comprising” (or its equivalents), also provide, as aspects, those which are independently described in terms of “consisting of” and “consisting essentially of.” 
     When values are expressed as approximations by use of the antecedent “about,” it will be understood that the particular value forms another aspect. In general, use of the term “about” indicates approximations that can vary depending on the desired properties sought to be obtained by the disclosed subject matter and is to be interpreted in the specific context in which it is used, based on its function, and the person skilled in the art will be able to interpret it as such. In some cases, the number of significant figures used for a particular value may be one non-limiting method of determining the extent of the word “about.” In other cases, the gradations used in a series of values may be used to determine the intended range available to the term “about” for each value. Where present, all ranges are inclusive and combinable. That is, reference to values stated in ranges includes each and every value within that range. 
     When a list is presented, unless stated otherwise, it is to be understood that each individual element of that list, and every combination of that list, is a separate aspect. For example, a list of aspects presented as “A, B, or C” is to be interpreted as including the aspects, “A,” “B,” “C,” “A or B,” “A or C,” “B or C,” or “A, B, or C.” 
     The terms “substantially parallel” as used herein in reference to two elements with respect to each other includes the two elements being close to, but not exactly, parallel to each other and the two elements being exactly parallel to each other. The terms “substantially perpendicular” as used herein in reference to two elements with respect to each other includes the two elements being close to, but not exactly perpendicular to each other, and the two elements being exactly perpendicular to each other. 
     Throughout this specification, words are to be afforded their normal meaning as would be understood by those skilled in the relevant art. However, so as to avoid misunderstanding, the meanings of certain terms will be specifically defined or clarified. 
     While the disclosure has been described in connection with the various aspects of the various figures, it will be appreciated by those skilled in the art that changes could be made to the aspects described above without departing from the broad inventive concept thereof. It is understood, therefore, that this disclosure is not limited to the particular aspects disclosed, and it is intended to cover modifications within the spirit and scope of the present disclosure as defined by the claims. 
     Features of the disclosure that are described above in the context of separate aspects may be provided in combination in a single aspect. Conversely, various features of the disclosure that are described in the context of a single aspect may also be provided separately or in any sub-combination. Finally, while an aspect may be described as part of a series of steps or part of a more general structure, each of the steps may also be considered an independent aspect in itself, combinable with others. 
     Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.