WO2024055062A1

WO2024055062A1 - Temperature sensing device and method

Info

Publication number: WO2024055062A1
Application number: PCT/AU2023/050841
Authority: WO
Inventors: Adam Weaver; Paul Van De Loo; Ben Klapaukh
Original assignee: Femtek Pty Ltd
Priority date: 2022-09-16
Filing date: 2023-08-31
Publication date: 2024-03-21

Abstract

Embodiments of the present invention provides a wearable device for temperature sensing. The wearable device comprises a first temperature sensor for detecting a surface temperature of a user, a second temperature sensor for detecting an ambient temperature proximate the first temperature sensor, and a controller being operatively configured to estimate a skin temperature for the user based on the detected surface temperature and the ambient temperature.

Description

TEMPERATURE SENSING DEVICE AND METHOD

Technical Field

[0001] The present invention generally relates to a temperature sensing device and method. In particular, the invention relates to a device, system and method for temperature sensing to estimate one or more phases in a user’s menstrual cycle.

Background

[0002] Wearable devices can be worn on the body to monitor and transmit information relating to various body signals including heart rate, temperature, movement and other vital signs to provide useful information and analytics to a user.

[0003] Menstrual Health is essential to the well-being and empowerment of women and adolescent girls. Keeping track of menstrual cycles can help women better understand their bodies, assist with family planning by providing guidance in relation to fertility (e.g., for the purpose of birth control or conception). In addition, the tracking of menstrual cycles may enable early detection of health issues. For example, an irregular menstrual cycle may indicate a hormone and/or thyroid issue, liver function problems, irritable bowel syndrome, diabetes or a host of other health conditions. Women can also experience menstrual changes when adopting a new exercise routine, gaining or losing a significant amount of weight, or simply going through a period of extreme stress.

[0004] Existing wearable devices for measuring body temperatures, such as a user’s skin temperature can be susceptible to errors. In particular, the temperature measurements from temperature sensors in existing wearable devices are often materially impacted by the ambient temperature. For example, an increase or decrease in the ambient temperature may erroneously translate to an increase or decrease to a skin temperature measurement, which can undesirably lead to an erroneous estimation of a user’s menstrual cycle. It has been discovered that this error was particularly pronounced for smart rings worn on fingers.

[0005] Some existing solutions for addressing this problem include adjusting the size of the smart ring to maximise contact between a temperature sensor and a user’s finger and using software solutions to filter out erroneous temperature readings. However, none of the existing solutions is capable of effectively excluding the influence of ambient temperature in skin temperature measurements.

[0006] Embodiments of the invention may provide wearable device, system and method of temperature sensing which overcomes or ameliorates one or more of the disadvantages or problems described above, or which at least provides the consumer with a useful choice.

[0007] A reference herein to a patent document or any other matter identified as prior art, is not to be taken as an admission that the document or other matter was known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims.

Summary of Invention

[0008] According to one aspect of the invention, there is provided a wearable device for temperature sensing, the device comprising a first temperature sensor for detecting a surface temperature of a user, and a second temperature sensor for detecting an ambient temperature proximate the first temperature sensor, and a controller being operatively configured to estimate a skin temperature for the user based on the detected surface temperature and the ambient temperature.

[0009] Advantageously, having a second temperature sensor to measure the ambient temperature allows the wearable device to take the effects of ambient temperature into account in the estimation of the user’s skin temperature, thereby enabling the wearable device to produce more accurate skin temperature estimates. In addition, the more accurate skin temperature estimates may be produced instantaneously in real-time or near real-time.

[0010] The wearable device may include an annular portion adapted to fit around a body portion of the user and contact the user’s skin. The annular portion may be adapted to fit around any suitable body portion of the user. For example, the annular portion may be adapted to fit around one or more of the user’s fingers, toes, wrists, arms, ankles, or legs. In one embodiment, the annular portion defines a ring for fitting around the user’s finger.

[0011] The annular portion may have an inner surface for making contact with the user’s skin and the first temperature sensor may be located proximate the inner surface. In some embodiments, the first temperature sensor may be mounted such that a portion of the first temperature sensor is generally flush with the inner surface of the annular portion so as to provide better contact between the user’s skin and a sensing element of the first temperature sensor.

[0012] The second temperature sensor may be located in the annular portion spaced from the first temperature sensor. In particular, the second temperature sensor may be spaced from the first temperature sensor in a radial direction of the annual portion.

[0013] The controller may be operatively configured to estimate the skin temperature of the user based on the formula:

wherein

Tskin is the estimated skin temperature of the user,

Tsurface is the surface temperature detected by the first temperature sensor, Rt is a thermal resistance value associated with the device, and

Tambient is the ambient temperature detected by the second temperature sensor.

[0014] The thermal resistance value (Rt) may be a predetermined value. In particular, the thermal resistance value (Rt) may be predetermined based on a thermal model of the wearable device when the device is fitted on a user’s body. Typically, the thermal resistance value (Rt) is a property of the wearable device and varies with the size, configuration and material(s) of the wearable device.

[0015] Advantageously, the estimation of the skin temperature value based on the values measured from both the first and second temperature sensors is capable of producing highly accurate skin temperature values. The estimated skin temperature may have a margin of error of less than 0.1 °C. In some embodiments, the estimated skin temperature may have a margin of error of about 0.01 °C or less. [0016] The first and second temperature sensors can be configured in any suitable manner. For example, the first temperature sensor and the second temperature sensor may be connected in parallel. Alternatively, the first temperature sensor and the second temperature sensor may be coupled to separate circuits.

[0017] In some embodiments, the wearable device may further include an accelerometer for detecting movement associated with the user. Generally, it is most desirable to determine skin temperature values when the user is at rest (for example when the user is sleeping) such that one or more phases of the user’s menstrual cycle can be estimated based on skin temperature trends measured over time. As movement such as exercise may momentarily raise the user’s skin temperature, the accelerometer may allow the controller to determine temperature measurements taken when the user is moving such that temperature measurements taken when the user’s movement is above a threshold can be ignored in the monitoring of skin temperature trends for the purpose of estimating one or more phases in the user’s menstrual cycle.

[0018] The wearable device may further include a battery for powering the first temperature sensor, second temperature sensor and controller, and a third temperature sensor for detecting a battery temperature. Any suitable type of battery may be used. In one embodiment, the battery may be rechargeable.

[0019] The detection of the battery temperature by the third temperature sensor may provide a safety feature whereby the wearable device is temporarily turned off if the battery temperature detected from the third temperature sensor exceeds a threshold. In particular, the battery temperature sensor may be a thermal switch, or coupled with a thermal switch.

[0020] The wearable device may further include a visual indicator for providing a visual indication of an operating status of the device. Any suitable visual indicator may be used. For example, the visual indicator may include an LED. The operating status of the device may include any one or more of a charging status, a fully charged status, and a battery low status. In some embodiments, the LED may emit different coloured light to indicate the different operating states for the wearable device. Moreover, the LED may emit one or more flashing light sequences to indicate one or more operating states.

[0021] The wearable device may further include a wireless communication module to enable wireless communication between the device and a computing device. Any suitable wireless communication module may be used. The wireless communication module may include a Bluetooth module. The Bluetooth module may be a Bluetooth Low Energy module.

[0022] The computing device may be any suitable computing device. For example, the computing device may be a mobile device, laptop, desktop computer. The wireless communication module may be operatively configured to communicate with any number of computing devices.

[0023] According to another aspect of the invention, there is provided a system for sensing a user’s skin temperature, the system including a wearable device as described herein, and a charger for charging the wearable device.

[0024] The charger may be shaped to hold the wearable device during charging. In particular, the charger may include a raised portion adapted for insertion into an opening of the annular portion of the wearable device during charging.

[0025] According to a further aspect of the invention, there is provided a method of estimating a user’s skin temperature, the method including receiving, via a first temperature, surface temperature data representative of surface temperature of a user, receiving, via a second temperature sensor, ambient temperature data representative of ambient temperature proximate the first temperature sensor, estimating a skin temperature for the user based on the surface temperature data and ambient temperature data.

[0026] The step of estimating the skin temperature may include estimating the skin temperature of the user based on the formula:

wherein

Tskin is the estimated skin temperature of the user,

Tambient is the ambient temperature detected by the second temperature sensor.

[0027] The method may further include receiving, via an accelerometer, movement data indicating a level of movement of the user, and ignoring the surface temperature data and corresponding ambient temperature data in the estimation of skin temperature when the associated movement data indicates that the user’s movement is above a predetermined threshold.

[0028] In some embodiments, the method may include ignoring the surface temperature data and corresponding ambient temperature data in the estimation of skin temperature when the associated movement data indicates that the user’s movement is above a predetermined threshold for a predetermined period of time.

[0029] The method described above is a computer implemented method. In particular, the method may be implemented on a microprocessor (controller) of the wearable device.

[0030] According to yet another aspect of the invention, there is provided a method of estimating one or more phases of a user’s menstrual cycle, the method including receiving one or more estimates of skin temperature for the user from a wearable device, wherein each estimate of skin temperature is determined based on a measured surface temperature of the user and a measured ambient temperature around the user, providing an estimation of one or more phases of a user’s menstrual cycle based on the one or more estimates of skin temperature.

[0031] The wearable device may be a wearable device as described herein.

[0032] The phases of the user’s menstrual cycle may include any one or more of menstruation, the follicular phase, ovulation and the luteal phase. Providing an estimation of one or more phases of a user’s menstrual cycle based on the one or more estimates of skin temperature may include providing an estimation of ovulation based on one or more estimates of skin temperature.

[0033] The estimation of one or more phases of a user’s menstrual cycle may be based on industry standard symptothermal method temperature rules. Typically, it is most desirable to take temperature measurements when the user is at rest (e.g. sleeping during the night). Changes in the average temperature measured over consecutive evenings can be used to estimate a phase in the menstrual cycle such as ovulation. Accordingly, ovulation may be estimated based on a comparison of daily temperature trends.

[0034] In one embodiment, the method may include receiving a first set of skin temperature data, the first set of skin temperature data being determined based on surface temperature data and ambient temperature data collected over a first period of time; receiving a second set of skin temperature data, the second set of skin temperature data being determined based on surface temperature data and ambient temperature data collected over a second period of time; determining a first average skin temperature based on the first set of skin temperature data, determining a second average skin temperature based on the second set of skin temperature data, determining a change in average skin temperature between the first average skin temperature and the second average skin temperature, and estimating ovulation based on the change in average skin temperature.

[0035] The first period of time may correspond to a first evening when the user is at rest, and the second period of time may correspond to a second evening when the user is at rest.

[0036] In this embodiment, the first and second sets of skin temperature may be determined based on temperature measurements collected over consecutive evenings whilst the user is at rest. In some embodiments, the method may include receiving a plurality of sets of skin temperature data, each set of skin temperature data being determined based on surface temperature data and ambient temperature data collected over one evening when the user is at rest. The plurality of sets of skin temperature data may be determined based on temperature data collected over consecutive evenings when the user is at rest.

[0037] The method may further include providing an estimation of menstruation based on the one or more estimates of skin temperature.

[0038] The method may further include providing a visual indication of the estimation of ovulation on a display. The display may be a display of a computing device such as a mobile device, laptop or desktop computer. The method may include generating a visual representation of the estimation of one or more phases in the user’s menstrual cycle, for example in the form of a graphical interface to illustrate one or more indicative dates for the estimated one or more phases in the menstrual cycle.

[0039] The methods described herein are computer implemented using software. The computer implemented methods may be executed on a processor (e.g. a microprocessor) in the wearable device, and/or a computing device with which the wearable device is operatively configured to communicate.

[0040] According to another aspect of the invention, there is provided a non- transitory computer readable medium having stored thereon software instructions that when executed by a processor, causes the processor to perform the steps of any one of the methods as described herein.

[0041] According to a further aspect of the invention, there is provided a data processing system comprising means for carrying out the steps of any one of the methods described herein.

[0042] According to yet another aspect of the invention, there is provided a computer-readable medium comprising instructions which, when executed by a computer, cause the computer to carry out the steps of any one of the methods described herein. [0043] In order that the invention may be more readily understood and put into practice, one or more preferred embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings.

[0044] It will be appreciated that for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

Brief Description of Drawings

[0045] FIGURE 1A is a schematic side view of a wearable device in the form of a smart ring according to one embodiment of the invention.

[0046] FIGURE 1 B is a partial view of the wearable device according to one embodiment of the invention.

[0047] FIGURE 2A is a key component layout of a partial printed circuit board (PCB) carrying the first and second temperature sensors of the wearable device as shown in Figure 1 .

[0048] FIGURE 2B is a schematic side view of the PCB shown in Figure 2A.

[0049] FIGURE 2C is a partial circuit diagram illustrating arrangement of the temperature sensors in the wearable device according to one embodiment of the invention.

[0050] FIGURE 3 is a schematic diagram of a thermal model of the wearable device show in Figure 1 .

[0051] FIGURE 4 illustrates a setup for determining the thermal resistance value Rt of the wearable device shown in Figure 1 .

[0052] FIGURE 5 is a schematic block diagram of the electronic modules in the wearable device shown in Figure 1 .

[0053] FIGURE 6 is a flow diagram illustrating a method of operating the wearable device shown in Figure 1 . [0054] FIGURE 7A is a graphical display illustrating variations in skin temperature across consecutive days determined based on data received from the wearable device of Figure 1 .

[0055] FIGURE 7B is a graphical display illustrating estimated ovulation dates based on the variations in skin temperature illustrated in Figure 6A.

[0056] FIGURE 7C is a graphical display illustrating estimated menstruation dates.

Detailed Description

[0057] Figure 1A illustrates a wearable device 100 in the form of a smart ring for measuring temperature associated with a user. The device 100 includes a generally annular body 1 10 having an inner surface 104 and an outer surface 106. A first temperature sensor 102 for detecting a surface temperature of the user when the device 100 is worn on the user’s finger is located proximate the inner surface 104. This allows the first temperature sensor 102 to measure the surface temperature of the user when the inner surface 102 is in contact with the user’s skin. A second temperature sensor 104 is also located within the annular body 110 of the device 100. The second temperature sensor 104 is spaced from the first temperature sensor 102 for detecting an ambient temperature proximate the first temperature sensor 102. The device 100 also includes a microcontroller 502 (see Figure 5) for receiving temperature data from the first and second sensors 102, 104 and estimating a skin temperature for the user based on the received temperature data from both sensors 102, 104.

[0058] According to one embodiment as shown in Figure 1 B, a base portion 112 of the annular body 110 may include interlocking members 114 and 116 that can be removably interlocked together to hold a printed circuit board (PCB) 200 (see Figures 2A and 2B). In particular, the PCB 200 may be seated in a recess 118 between the interlocking members 114, 116. The interlocking member 116 may include a further recess 120 for receiving the second sensor 104 therein.

[0059] A key component layout of the printed circuit board (PCB) 200 is shown in Figures 2A and 2B. The PCB 200 is flexible and adapted for mounting within the annular body 110 of the device 100 such that the first and second temperature sensors 102, 104 are positioned as shown in Figure 1. The second temperature sensor 104 is mounted on a tab portion 106 of the PCB 200. The tab portion 106 can be folded along a fold line 108 as shown in Figure 2B such that the second temperature sensor 104 is spaced from the first temperature sensor 102 to measure the ambient temperature 102 around the first temperature sensor 102.

[0060] The microcontroller 502 is operatively configured to estimate the skin temperature of the user based on the formula (1) below:

wherein

Tskin is the estimated skin temperature of the user,

Tambient is the ambient temperature detected by the second temperature sensor.

[0061] Formula (1) allows an accurate skin temperature of the user to be estimated as it takes into consideration thermal properties of the wearable device 100 and the ambient temperature. The thermal resistance value (Rt) is predetermined based on a thermal model of the wearable device when the device is fitted on a user’s body as described in further detail below with reference to Figure 3. Typically, the thermal resistance value (Rt) is a property of the wearable device 100 and varies with the size, configuration and material(s) of the wearable device 100.

[0062] A schematic diagram of the temperature sensing circuit 202 is illustrated in Figure 2C. The temperature sensing circuit 202 forms part of the PCB 200 as shown in Figures 2A and 2B. In circuit 202, the first temperature sensor 102 is provided by a first thermistor 206, and the second temperature sensor 104 is provided by a second thermistor 208. A battery temperature sensor 504 (Figure 5) is provided by a third thermistor 204. The three thermistors 204, 206, 208 are connected in parallel. Each thermistor 204, 206, 208 is also connected in series with a resistor R (e.g. each having a known resistance value of 10KQ). For a given input voltage (Vin), a corresponding variable resistance value ARB, ARi, R2 for each thermistor 204, 206, 208 can be determined based on the voltage divider equations (2) - (4) below: (2)

(3)

(4) wherein,

VB is the measured voltage across the third thermistor 204 (battery temperature sensor 504),

Vi is the measured voltage across the first thermistor 206 (first temperature sensor 102 measuring surface temperature),

V2 is the measured voltage across the second thermistor 206 (second temperature sensor 104 measuring ambient temperature),

Vin is input voltage (e.g. 3.3V) or total voltage across each thermistor and corresponding resistor Ro ,

Ro is the known resistance value of resistor R couped in series with each thermistor,

ARB is the resistance value of the third thermistor 204 (battery temperature sensor 504),

AR1 is the resistance value of the first thermistor 206 (first temperature sensor 102 measuring surface temperature),

AR2 is the resistance value of the second thermistor 208 (second temperature sensor 104 measuring ambient temperature).

[0063] Once the resistance value RB, AR1, AR2 for each thermistor 204, 206, 208 is determined, the corresponding temperature value in °C can be determined based on a datasheet/specification for each thermistor 204, 206, 208.

[0064] A thermal model 300 of the wearable device 100 is shown in Figure 3. As illustrated in the thermal model 300:

Tskin is the estimated skin temperature of the user,

Rti is the thermal resistance between the user’s skin and the first temperature sensor 102, Tsurface is the surface temperature measured by the first temperature sensor 102,

Rt2 is the thermal resistance between the first temperature sensor 102 and the second temperature sensor 104,

Tambient is the ambient temperature measured by the second temperature sensor,

Rt3 is the thermal resistance between the outside if the device 100 and the second temperature sensor 104,

Tamb’ is the real ambient temperature

Q is the thermal current passing through the device 100.

[0065] In accordance with ohms law, equation (5) can be established as follows:

[0066] Equation (1 ) above can be derived from equation (5), wherein the thermal resistance value Rt from equation (1 ) can be expressed as follows:

[0067] The thermal resistance value Rt can be predetermined based on the specific configuration, material and size of the wearable device 100 using experimental methods. An example experimental setup 400 is illustrated in Figure 4, in which a temperature-controlled module 402 is provided. The temperature-controlled module 402 includes a plurality of cylindrical portions 404 extending outwardly from a base 406. Each cylindrical portion 404 is adapted to receive a device 100 mounted thereon. The module 402 includes a control system (not shown) for controlling the temperature of the cylinders 404. The control system includes one or more heating elements for heating the cylinders 404, one or more thermistors for determining a temperature of the cylinders 404 and a controller such as a PID controller for varying the heating elements such that the cylinders 404 can be heated to one or more set temperatures.

[0068] Using setup 400, the thermal resistance value Rt can be solved based on formula (1) above. In particular, the cylinders 404 can be heated to a plurality of known set temperatures (e.g. 35°C to 40°C in 0.5°C increments). The set temperatures of the cylinders 404 simulate the skin temperature of the user Tskin. The measured surface temperatures Tsurface from the first temperature sensor 102 and measured ambient temperatures Tambient from the second temperature sensor 104 of each device 100 can be used together with the corresponding set temperature values for Tskin to determine the thermal resistance value Rt using formula (1 ). Once the thermal resistance value Rt for a particular device 100 is determined, the thermal resistance value Rt can be uploaded to the controller 502 of each device 100 via a wireless communication module 506 (Figure 5).

[0069] Now referring to Figure 5, a schematic block diagram of the temperature sensing system 500 of the device 100 is shown. The temperature sensing system 500 is provided on the flexible PCB 200 as shown in Figure 2A and 2B. The system 500 includes a microcontroller 502 for receiving input from the different sensors and determining estimated skin temperature data for communication with an external computing device (as discussed in further detail below with reference to Figure 6). The sensors include the first temperature sensor 102, the second temperature sensor 104, the battery temperature sensor 504 and an accelerometer 508.

[0070] The battery temperature sensor 504 measures the temperature of rechargeable battery module 510. In the event that the measured battery temperature sensor 504 is too high, and exceeds a predetermined temperature (e.g. 50°C ), the system 500 can be temporarily turned off until the temperature sensor 504 returns a temperature reading below the threshold. The temperature sensor 504 may be a thermal switch. Alternatively, the temperature sensor may be a thermistor coupled to the charging controller 516 for turning off the system 500 when the measured battery temperature sensor 504 exceeds a predetermined temperature.

[0071] The accelerometer 508 is configured to detect movement associated with the user. As will be described in further detail below with reference to Figure 6, it is most desirable to determine skin temperature values when the user is at rest (for example when the user is sleeping) such that one or more phases of the user’s menstrual cycle can be estimated based on skin temperature trends measured over consecutive days. As movement such as exercise may momentarily raise the user’s skin temperature, the accelerometer 508 allows the microcontroller 502 to determine temperature measurements taken when the user is moving such that temperature measurements taken when the user’s movement is above a threshold can be ignored in the monitoring of skin temperature trends for the purpose of estimating one or more phases in the user’s menstrual cycle.

[0072] The system 500 also includes an LED 512 for providing a visual indication of an operating status of the device 100. For example, the LED 512 may be operatively configured to emit different coloured light and/or emit light according to a different flash sequence to indicate different operating states of the system 500. Some operating states of the system 500 may include a charging state, a fully charged state, a low battery state, non-charging state, Bluetooth connected state, Bluetooth disconnected state, error state, normal operation state, data collection state, data transfer state, off or in sleep/ship mode (e.g. LED off). A battery fuel gauge 520 measures the current battery level of the battery 510 and reports to the microcontroller 502. Based on the current battery level, the microcontroller 502 generates a corresponding control signal for the LED to indicate the operating state.

[0073] The system 500 also includes a charger 514 for charging the battery 510. The charger 514 can be a wireless charger. Alternatively, the system 500 may include a charging port (not shown) for charging via a charge cable and USB power supply.

[0074] When the device 100 is placed on the charger 514, the battery 510 is charged via charging controller 516. The charger 514 includes a wireless communication module (not shown) for communication with the microcontroller 512. The charging controller 516 determines when to draw power from the charger 514 to charge the battery 510. A regulator 518 is used to regulate power to the microcontroller 502.

[0075] A method 600 of operating the wearable device 100 will now be described with reference to Figure 6.

[0076] The method 600 includes a method 602 of estimating a user’s skin temperature using device 100, and a method 624 of determining one or more phases in a user’s menstrual cycle based on the estimated skin temperature data from method 602. Typically, the method 602 is implemented using embedded software on the microcontroller 502 of the temperature sensing system 500, and the method 604 is implemented as a software application on a computing device (not shown) such as a mobile device or personal computer. The estimated skin temperature data from the microcontroller 502 can be transmitted to the computing device via any suitable communication means, including wireless or wired communication.

[0077] The method 602 of estimating a user’s skin temperature will now be described with reference to method steps 606 to 624.

[0078] At step 606, a user removes the device 10 from charging device 514 and places the device 10 on a finger before going to sleep at night.

[0079] At step 608, the microcontroller 502 receives temperature data from the first and second sensors 102, 104 simultaneously. Step 608 includes sub-steps 610 and 612. At sub- step 610, a voltage measurement Vi is received from the first thermistor. Simultaneously at sub-step 612, a voltage measurement V2 is received from the second thermistor.

[0080] At step 614, the voltage measurement Vi is converted to a surface temperature measurement in °C based on equation (3) and as described above with reference to Figure 2C.

[0081] At step 616, the voltage measurement V2 is converted to an ambient temperature measurement in °C based on equation (4) and as described above with reference to Figure 2C.

[0082] At step 618, the skin temperature of the user is estimated using equation (1) based on the surface temperature measurement from step 614 and the ambient temperature measurement from step 616.

[0083] At step 620, the estimated skin temperature data is stored in system 500 memory.

[0084] At query step 622, the microcontroller 502 determines whether the user has placed the device 100 back on the charger 514 (e.g., after the user has woken up from one night’s sleep). The microcontroller 502 determines whether the device 100 is on the charger 514 by querying the charger 514. If the device 100 is not on the charger 514 (e.g. the user is still sleeping), the method 602 returns to step 608 and the process of measuring temperature data and estimating skin temperature data in steps 608 to 620 is repeated until the device 100 is returned to the charger 514. If not (e.g. the use has woken up and the start of the next day), the method 602 proceeds to step 624.

[0085] At step 624, the microcontroller 502 sends all data including the estimated skin temperature data stored in memory to the software application on the computing device.

[0086] A method 604 of determining one or more phases in a user’s menstrual cycle based on the estimated skin temperature data from method 602 will now be described with reference to steps 626 to 634.

[0087] At step 626, the software application on the computing device filters out any bad data received from the microcontroller 502. Bad data may include erroneous data, temperature data associated with excess user movement, temperature data when the device 100 is removed from the user’s finger and the like. It may be determined that the device 100 is removed from the user’s finger but not returned to the charger 514 if the surface temperature measurement from the first temperature sensor 102 is equal to the ambient temperature measurement from the second temperature sensor 104.

[0088] At step 628, the software application calculates an average skin temperature value based on the estimated skin temperature data collected over each night that the user has worn on the device 100.

[0089] At step 630, the software application determines a change in the average skin temperature value from one night to the next.

[0090] At step 632, the software application performs data analytics based on the data received from the device 100. In particular, the software application estimates one or more phases of the user’s menstrual cycle based on the changes in the average skin temperature values determined in step 630. The different phases of menstrual cycle include menstruation, the follicular phase, ovulation and the luteal phase. Typically, the estimation of one or more phases of a user’s menstrual cycle is implemented based on industry standard symptothermal method temperature rules. The symptothermal method temperature rules correlates phases in the menstrual cycle with body temperature.

[0091] At step 634, the estimation of the one or more phases in the user’s menstrual cycle is presented to the user graphically via a user interface of the computing device.

[0092] As illustrated in Figure 7A, a graphical interface 700 generated by the software application plots the changes in nightly average skin temperature against the dates on which the temperature measurements 610, 612 were taken.

[0093] Figure 7B illustrates a graphical interface 720 generated by the software application providing an indication of ovulation dates 722 for a particular month.

[0094] Figure 7C illustrates a graphical interface 740 generated by the software application providing an indication of menstruation dates 722 for a particular month.

Interpretation

[0095] This specification, including the claims, is intended to be interpreted as follows:

[0096] Embodiments or examples described in the specification are intended to be illustrative of the invention, without limiting the scope thereof. The invention is capable of being practised with various modifications and additions as will readily occur to those skilled in the art. Accordingly, it is to be understood that the scope of the invention is not to be limited to the exact construction and operation described or illustrated, but only by the following claims.

[0097] The mere disclosure of a method step or product element in the specification should not be construed as being essential to the invention claimed herein, except where it is either expressly stated to be so or expressly recited in a claim.

[0098] The terms in the claims have the broadest scope of meaning they would have been given by a person of ordinary skill in the art as of the relevant date. [0099] The terms "a" and "an" mean "one or more", unless expressly specified otherwise.

[0100] Neither the title nor the abstract of the present application is to be taken as limiting in any way as the scope of the claimed invention.

[0101] Where the preamble of a claim recites a purpose, benefit or possible use of the claimed invention, it does not limit the claimed invention to having only that purpose, benefit or possible use.

[0102] It should be noted that terms of degree such as “generally”, “substantially”, “about” and “approximately” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. These terms of degree should be construed as including a deviation of the modified term if this deviation would not negate the meaning of the term it modifies.

[0103] In the specification, including the claims, the term “comprise”, and variants of that term such as “comprises” or “comprising”, are used to mean "including but not limited to", unless expressly specified otherwise, or unless in the context or usage an exclusive interpretation of the term is required.

[0104] Furthermore, the recitation of any numerical ranges by endpoints herein includes all numbers and fractions subsumed within that range (e.g. 1 to 5 includes 1 , 1.5, 2, 2.75, 3, 3.90, 4, and 5). It is also to be understood that all numbers and fractions thereof are presumed to be modified by the term “about” which means a variation up to a certain amount of the number to which reference is being made if the end result is not significantly changed.

[0105] As used herein, the wording “and/or” is intended to represent an inclusive- or. That is, “X and/or Y” is intended to mean X or Y or both, for example. As a further example, “X, Y, and/or Z” is intended to mean X or Y or Z or any combination thereof.

[0106] The disclosure of any document referred to herein is incorporated by reference into this patent application as part of the present disclosure, but only for purposes of written description and enablement and should in no way be used to limit, define, or otherwise construe any term of the present application where the present application, without such incorporation by reference, would not have failed to provide an ascertainable meaning. Any incorporation by reference does not, in and of itself, constitute any endorsement or ratification of any statement, opinion or argument contained in any incorporated document.

Claims

The claims defining the invention are as follows

1 . A wearable device for temperature sensing, the device comprising a first temperature sensor for detecting a surface temperature of a user, and a second temperature sensor for detecting an ambient temperature proximate the first temperature sensor, and a controller being operatively configured to estimate a skin temperature for the user based on the detected surface temperature and the ambient temperature.

2. The device of claim 1 , wherein the device includes an annular portion adapted to fit around a body portion of the user and contact the user’s skin.

3. The device of claim 2, wherein the annular portion defines a ring for fitting around the user’s finger.

4. The device of claim 2 or 3, wherein the annular portion has inner surface for making contact with the user’s skin and the first temperature sensor is located proximate the inner surface.

5. The device according to any one of claims 2 to 4, wherein the second temperature sensor is located in the annular portion and spaced from the first temperature sensor.

6. The device according to any one of claims 1 to 5, wherein the controller is operatively configured to estimate the skin temperature of the user based on the formula:

wherein

Tskin is the estimated skin temperature of the user,

Tsurface is the surface temperature detected by the first temperature sensor,

Rt is a thermal resistance value associated with the device, and Tambient is the ambient temperature detected by the second temperature sensor.

7. The device of claim 6, wherein the thermal resistance value (Rt) is a predetermined value.

8. The device according to any one of the preceding claims, wherein the estimated skin temperature has a margin of error of less than 0.1 °C.

9. The device of any one of the preceding claims, wherein the first temperature sensor and the second temperature sensor are connected in parallel.

10. The device according to any one of the preceding claims, further including an accelerometer for detecting movement associated with the user.

1 1 . The device according to any one of the preceding claims, further including a battery for powering the first temperature sensor, second temperature sensor and controller, and a third temperature sensor for detecting a battery temperature.

12. The device according to claim 1 1 , wherein the battery is rechargeable.

13. The device according to claim 1 1 or 12, wherein the device is temporarily turned off if the battery temperature detected from the third temperature sensor exceeds a threshold.

14. The device according to any one of the preceding claims, further including a visual indicator for providing a visual indication of an operating status of the device, wherein the operating status of the device includes any one or more of a charging status, a fully charged status, and a battery low status.

15. The device according to any one of the preceding claims, further including a wireless communication module to enable wireless communication between the device and a computing device.

16. A system for sensing a user’s skin temperature, the system including a wearable device according to any one of the preceding claims, and a charger for charging the wearable device. A computer implemented method of estimating a user’s skin temperature, the method including receiving, via a first temperature, surface temperature data representative of surface temperature of a user, receiving, via a second temperature sensor, ambient temperature data representative of ambient temperature proximate the first temperature sensor, and estimating a skin temperature for the user based on the surface temperature data and ambient temperature data. The method of claim 17, wherein the step of estimating the skin temperature includes estimating the skin temperature of the user based on the formula:

wherein

Tskin is the estimated skin temperature of the user,

Tsurface is the surface temperature detected by the first temperature sensor,

Rt is a thermal resistance value associated with the device, and Tambient is the ambient temperature detected by the second temperature sensor. The method according to claim 17 or 18, further including receiving, via an accelerometer, movement data indicating a level of movement of the user, and ignoring the surface temperature data and corresponding ambient temperature data in the estimation of skin temperature when the associated movement data indicates that the user’s movement is above a predetermined threshold. A computer-implemented method of estimating one or more phases of a user’s menstrual cycle, the method including receiving one or more estimates of skin temperature for the user from a wearable device, wherein each estimate of skin temperature is determined based on a measured surface temperature of the user and a measured ambient temperature around the user, and providing an estimation of one or more phases of a user’s menstrual cycle based on the one or more estimates of skin temperature. The method of claim 21 , wherein the step of providing an estimation of one or more phases of a user’s menstrual cycle includes providing an estimation of ovulation. The method of claim 20 or 21 , including receiving a first set of skin temperature data, the first set of skin temperature data being determined based on surface temperature data and ambient temperature data collected over a first period of time; receiving a second set of skin temperature data, the second set of skin temperature data being determined based on surface temperature data and ambient temperature data collected over a second period of time; determining a first average skin temperature based on the first set of skin temperature data, determining a second average skin temperature based on the second set of skin temperature data, determining a change in average skin temperature between the first average skin temperature and the second average skin temperature, and estimating the one or more phases of the user’s menstrual cycle based on the change in average skin temperature. The method of claim 21 , wherein the first period of time corresponds to a first evening when the user is at rest, and the second period of time corresponds to a second evening when the user is at rest.

24. The method according to any one of claims 20 to 23, wherein the step of providing an estimation of one or more phases of a user’s menstrual cycle includes providing an estimation of menstruation based on the one or more estimates of skin temperature. 25. The method according to any one of claims 20 to 24, further including providing a visual indication of the estimated one or more phases of the user’s menstrual cycle on a display.

26. The method according to any one of claims 20 to 24, wherein the wearable device is a wearable device according to any one of claims 1 to 15. 27. A non-transitory computer readable medium having stored thereon software instructions that when executed by a processor, causes the processor to perform a method according to any one of claims 17 to 26.