PATENT DOCUMENT

Publication Number: US-11635334-B2
Application Number: US-202016917704-A
Country: US
Kind Code: B2

Title: Miniature external temperature sensing device for estimating subsurface tissue temperatures

Abstract:
Embodiments described herein are directed to a temperature measurement device that includes a sensor body configured to be placed on a skin of a user. The temperature measurement device can include a first section defining a first lower surface and having a first thickness, a second section defining a second lower surface and having a second thickness, and a channel separating the first lower surface from the second lower surface. The temperature measurement device can also include a first set of temperature sensors positioned across the first thickness, a second set of temperature sensors positioned across the second thickness, and a processor configured to estimate a tissue temperature of the user based on comparing temperature signals from the first set of temperature sensors with temperature signals from the second set of temperature sensors.

Claims:
What is claimed is: 
     
       1. A temperature measurement device, comprising:
 a sensor body configured to be placed on a skin of a user, the sensor body comprising:
 a first section defining a first upper surface and a first lower surface and having a first thickness; 
 a second section defining a second upper surface and a second lower surface and having a second thickness; 
 a first channel separating between the first lower surface from and the second lower surface; and 
 a second channel between the first upper surface and the second upper surface: 
 
 a first set of temperature sensors positioned across the first thickness; 
 a second set of temperature sensors positioned across the second thickness; and 
 a processor configured to estimate a tissue temperature of the user based on comparing temperature signals from the first set of temperature sensors with temperature signals from the second set of temperature sensors. 
 
     
     
       2. The temperature measurement device of  claim 1 , wherein:
 the sensor body further defines:
 a third lower surface positioned between the first and second lower surfaces; and 
 a second channel; 
 
 the first channel is between the first lower surface and the third lower surface; and 
 the second channel is between the second lower surface and the third lower surface. 
 
     
     
       3. The temperature measurement device of  claim 2 , wherein:
 the first set of temperature sensors has a first temperature sensor positioned on the first lower surface and a second temperature sensor positioned on a first upper surface of the first section; and 
 the second set of temperature sensors has a third temperature sensor positioned on the second lower surface and a fourth temperature sensor positioned on a second upper surface of the second section. 
 
     
     
       4. The temperature measurement device of  claim 1 , wherein:
 the first section defines an upper surface opposite the first lower surface; and 
 a depth of the channel extends towards the upper surface. 
 
     
     
       5. The temperature measurement device of  claim 1 , wherein:
 the first section defines a first cylindrical body; and 
 the second section defines a second cylindrical body. 
 
     
     
       6. The temperature measurement device of  claim 5 , wherein the second section extends around the first section. 
     
     
       7. The temperature measurement device of  claim 1 , wherein:
 the sensor body is symmetric about an axis; and 
 the channel extends in a circle around the axis. 
 
     
     
       8. The temperature measurement device of  claim 1 , wherein:
 the sensor body comprises a conductive material; and 
 the channel contains an insulating material. 
 
     
     
       9. The temperature measurement device of  claim 1 , further comprising a substrate positioned on the first and second lower surfaces and configured to contact the skin of the user. 
     
     
       10. A temperature sensor, comprising:
 a sensor body for measuring a temperature of a user, the sensor body comprising:
 a first section defining a first lower surface that is offset from a first upper surface; 
 a second section defining a second lower surface that is offset from a second upper surface, wherein a first thickness between the first lower surface and the first upper surface is greater than a second thickness between the second lower surface and the second upper surface; and 
 a first channel between the first lower surface and the second lower surface; 
 a second channel between the first upper surface and the second upper surface: 
 
 a first set of temperature sensors positioned on the first section; 
 a second set of temperature sensors positioned on the second section; and 
 a processor configured to estimate a tissue temperature of the user based on comparing temperature signals from the first set of temperature sensors with temperature signals from the second set of temperature sensors. 
 
     
     
       11. The temperature sensor of  claim 10 , wherein:
 the first set of temperature sensors includes a first sensor positioned on the first lower surface and a second sensor positioned on the first upper surface; and 
 the second set of temperature sensors includes a third sensor positioned on the second lower surface and a fourth sensor positioned on the second upper surface. 
 
     
     
       12. The temperature sensor of  claim 10 , wherein the first and second lower surfaces are configured to be placed against a skin of the user. 
     
     
       13. The temperature sensor of  claim 10 , wherein the sensor body further defines:
 a third lower surface that is separated from the first lower surface by the first channel; and 
 a third channel that separates the third lower surface from the second lower surface. 
 
     
     
       14. The temperature sensor of  claim 10 , wherein the sensor body is a conductive material and the first channel comprises insulating material. 
     
     
       15. The temperature sensor of  claim 10 , wherein first section forms a central part of the sensor body and the second section forms an outer part of the sensor body. 
     
     
       16. A temperature sensor, comprising:
 a sensor body for measuring a temperature of a user, the sensor body defining:
 first and second lower surfaces that are configured to be placed against a skin of the user; 
 a first upper surface offset from and opposite the first lower surface; 
 a second upper surface offset from and opposite the second lower surface, wherein a first thickness between the first lower surface and the first upper surface is greater than a second thickness between the second lower surface and the second upper surface; and 
 a first channel positioned between the first and second lower surfaces; 
 a second channel positioned between the first and second upper surfaces: 
 
 a set of temperature sensors that are configured to measure temperatures at the first lower surface, the second lower surface, the first upper surface, and second upper surface; and 
 a processer configured to estimate a tissue temperature of the user based on the temperature measurements from the set of temperature sensors. 
 
     
     
       17. The temperature sensor of  claim 16 , wherein the sensor body further defines:
 a third lower surface positioned between the first and second lower surfaces; and 
 a third channel positioned between the first and second lower surfaces. 
 
     
     
       18. The temperature sensor of  claim 17 , wherein the set of temperature sensors comprises:
 a first temperature sensor positioned on the first lower surface; 
 a second temperature sensor positioned on the first upper surface; 
 a third temperature sensor positioned on the second lower surface; and 
 a fourth temperature sensor positioned on the second upper surface. 
 
     
     
       19. The temperature sensor of  claim 16 , wherein:
 the sensor body comprises a conductive material; and 
 the channel comprises an insulating material.

Description:
FIELD 
     The described embodiments relate generally to temperature sensing devices, and more particularly, to an external temperature sensing device configured to estimate subsurface tissue temperatures. 
     BACKGROUND 
     Wearable electronic devices, such as smart watch, smart glasses, earphones, and so on, are typically worn by a user throughout the day and may include various sensors to measures physiological parameters of a user and/or environmental parameters. The wearable device can contain various sensing devices for determining one or more physiological parameters of a user such as temperature, heart rate, blood oxygen level, and so on. The sensing devices can include a temperature sensing device, which may be used to measure a temperature of a user. Traditional temperature sensing devices may take a relatively long time (in some cases, minutes) to take a measurement of a user and/or only be able to detect a skin surface temperature of a user. In some cases, it may be desirable to have a wearable or portable electronic device that can more quickly and accurately determine skin or subsurface (e.g., deep tissue) temperature of a user. 
     SUMMARY 
     Embodiments herein are directed to a temperature measurement device that includes a sensor body configured to be placed on a skin of a user, where the sensor body includes a first section defining a first lower surface and having a first thickness, and a second section defining a second lower surface and having a second thickness. The sensor body can also define a channel separating the first lower surface from the second lower surface. The temperature measurement device can include a first set of temperature sensors positioned across the first thickness, a second set of temperature sensors positioned across the second thickness, and a processor configured to estimate a tissue temperature of the user based on comparing temperature signals from the first set of temperature sensors with temperature signals from the second set of temperature sensors. 
     In some cases, the channel is a first channel, and the sensor body further defines a third lower surface positioned between the first and second lower surfaces, and a second channel. The first channel can separate the first lower surface from the third lower surface, and the second channel can separate the second lower surface from the third lower surface. The first set of temperature sensors can have a first temperature sensor positioned on the first lower surface and a second temperature sensor positioned on a first upper surface of the first section. The second set of temperature sensors can have a third temperature sensor positioned on the second lower surface and a fourth temperature sensor positioned on a second upper surface of the second section. 
     In some examples, the first section defines an upper surface that is opposite the first lower surface. A depth of the channel can extend towards the upper surface. The first section can define a first cylindrical body, and the second section can define a second cylindrical body. In some examples, the second section extends around the first section. The sensor body can be symmetric about an axis, and the channel can extend in a circle around the axis. The sensor body can include a conductive material, and the channel can contain an insulating material. In some cases, a substrate is positioned on the first and second lower surfaces and configured to contact the skin of the user. 
     Embodiments are also directed to a temperature sensor that includes a sensor body for measuring a temperature of a user. The sensor body can include a first section defining a first lower surface that is offset from a first upper surface, and a second section defining a second lower surface that is offset from a second upper surface. A first thickness between the first lower surface and the first upper surface can be greater than a second thickness between the second lower surface and the second upper surface. A channel can separate the first lower surface from the second lower surface. A first set of temperature sensors can be positioned on the first section, a second set of temperature sensors can be positioned on the second section, and a processor can be configured to estimate a tissue temperature of the user based on comparing temperature signals from the first set of temperature sensors with temperature signals from the second set of temperature sensors. 
     The first set of temperature sensors can include a first sensor positioned on the first lower surface and a second sensor positioned on the first upper surface. The second set of temperature sensors can include a third sensor positioned on the second lower surface and a fourth sensor positioned on the second upper surface. The first and second lower surfaces can be configured to be placed against a skin of the user. In some cases, the sensor body can further define a third lower surface that is separated from the first lower surface by the first channel, and a second channel that separates the third lower surface from the second lower surface. The sensor body can further define a third channel that separates the first upper surface from the second upper surface. The sensor body can be a conductive material and the first channel can include an insulating material. In some cases, the first section forms a central part of the sensor body and the second section forms an outer part of the sensor body. 
     Embodiments are also directed to a temperature sensing device that includes a sensor body for measuring a temperature of a user. The sensor body can define first and second lower surfaces that are configured to be placed against a skin of the user. The sensor body can also define a first upper surface offset from and opposite the first lower surface, and a second upper surface offset from and opposite the second lower surface. A first thickness between the first lower surface and the first upper surface can be greater than a second thickness between the second lower surface and the second upper surface, and a channel can be positioned between the first and second lower surfaces. A set of temperature sensors can be configured to measure temperatures at the first lower surface, the second lower surface, the first upper surface, and second upper surface. A processer can be configured to estimate a tissue temperature of the user based on the temperature measurements from the set of temperature sensors. 
     The channel can be a first channel and the sensor body can further define a third lower surface positioned between the first and second lower surfaces, and a second channel positioned between the first and second lower surfaces. The set of temperature sensors can include a first temperature sensor positioned on the first lower surface, a second temperature sensor positioned on the first upper surface, a third temperature sensor positioned on the second lower surface, and a fourth temperature sensor positioned on the second upper surface. The sensor body can include a conductive material and the channel can include an insulating material. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG.  1    shows an example electronic device that includes a temperature sensing device; 
         FIGS.  2 A and  2 B  illustrate an example temperature sensing device that can be included in an electronic device; 
         FIG.  3    is a cross-sectional view of an example temperature sensing device; 
         FIG.  4    is a cross-sectional view showing a temperature distribution of an example temperature sensing device; 
         FIG.  5    is a cross-sectional view of an example temperature sensing device; 
         FIGS.  6 A- 6 D  show cross-sectional views of example temperature sensing devices; and 
         FIG.  7    is a block diagram illustrating an example electronic device, which can incorporate a temperature sensing device. 
     
    
    
     The use of cross-hatching or shading in the accompanying figures is generally provided to clarify the boundaries between adjacent elements and also to facilitate legibility of the figures. Accordingly, neither the presence nor the absence of cross-hatching or shading conveys or indicates any preference or requirement for particular materials, material properties, element proportions, element dimensions, commonalities of similarly illustrated elements, or any characteristics attribute, or property for any element illustrated in the accompanying figures. 
     Additionally, it should be understood that the proportions and dimensions (either relative or absolute) of the various features and elements (and collections and groupings thereof) and the boundaries, separations, and positional relationships presented therebetween, are provided in the accompanying figures merely to facilitate an understanding of the various embodiments described herein and, accordingly, may not necessarily be presented or illustrated to scale, and are not intended to indicate any preference or requirement for an illustrated embodiment to the exclusion of embodiments described with reference thereto. 
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     Embodiments disclosed herein are directed to miniature temperature sensing devices for use in, or incorporation into, portable and/or wearable electronic devices. The temperature sensing device can be used to estimate a subsurface tissue temperature of a user by measuring temperatures at the skin of the user. It may be desirable to estimate subsurface tissue temperatures of a user as these temperatures may be more stable over time and/or accurate in determining a current condition of a user such as whether they have an elevated or depressed temperature. 
     In some embodiments, the temperature sensing device can have a sensor body that has two sections of different thicknesses and two or more sets of temperature sensors configured to measure temperature differentials across the different sections. Such temperature sensing devices may be referred to as “dual heat flux temperature sensors.” Dual heat flux temperature sensors may be placed such that the sensor body is on a surface, such as a skin of a user; the temperature sensor may estimate a subsurface temperature (e.g., a deep tissue temperature of a user) by measuring temperature differences across the two different thicknesses of the sensor body. For example, the sensor body can have an inner cylindrical section that is thicker or taller than an outer toroidal section that extends around a circumference of the inner section, such that the sensor body defines a top hat-like structure. A first set of temperatures sensors can be positioned to measure temperature differences across the thicker, inner cylindrical section and a second set of temperature sensors can be positioned to measure temperature differences across the thinner, outer toroidal section. The temperature differentials across each of these sections can be used to estimate the subsurface tissue temperature of a user. In some cases, additional sets of temperature sensors may be placed at different locations along the first and/or second sections, which may help increase the accuracy of the temperature measurements across each of the sections. 
     Embodiments described herein are directed to temperature sensing devices that include one or more channels separating a thicker, inner section from a thinner, outer section. The channels can be positioned on a bottom, skin-contacting surface of the sensor body may be ring-shaped to separate a bottom (or skin-contacting) surface of the inner section from a bottom (or skin-contacting) surface of the outer section. The channels can thermally isolate the first section from the second section to reduce heat transfer between the first and second sections. This configuration may provide a greater temperature differential between the first and second sections than if the channels were absent, which, in turn, can improve the accuracy of deep tissue temperature estimations. In some embodiments, the sensor body is formed from a first material such as a metal, polymer, composite material, or the like, and the channel can contain air or another gas that has lower thermal conductivity than the first material. In some cases, the channel can contain a second insulating material such as foam that has lower thermal conductivity than the first material. In certain examples, the channel may be under vacuum. 
     In some examples, a radial or ring-shaped channel can also be formed on an upper surface of the sensor body and positioned between the thicker, inner section (the “first section”) and the thinner, outer section (the “second section”). This upper channel can further reduce heat flow between the first and second sections. 
     Reducing the heat flow between the first and second sections can allow the temperature sensing device to be decreased in size as compared to similar sensors that lack the insulating channels, while still accurately estimating deep tissue temperature. As previously mentioned, the deep tissue temperature of a user may be estimated by comparing a first temperature differential across the thicker section with a second temperature differential across the second section. As the size of the sensor body is decreased, heat transfer between the thicker section and the thinner section may have a greater impact on each section&#39;s temperature differential because the body of the temperature sensor may have smaller thermal gradients across it and thus between sensors, thereby reducing an accuracy of the device. Incorporating channels into the sensor body can reduce heat transfer between these sections to improve the accuracy of dual heat flux temperature sensing devices; this, in turn, permits a dual heat flux temperature sensor to be scaled down while maintaining temperature gradients and thus accuracy. Additionally or alternatively, decreasing the size of the temperature sensing device can decrease the time needed to take the temperature measurements to estimate a deep tissue temperature. These smaller temperature sensing devices can be referred to as “miniature dual heat flux temperature sensors.” 
     Miniature dual heat flux temperature sensors can be incorporated into a variety of electronic devices such as smart watches, mobile phones, tablet computing devices, laptop computing devices, personal digital assistants, digital media players, other wearable devices (including glasses, jewelry, clothing, and earphones), and the like to estimate a deep tissue temperature of a user of the device. For example, a miniature dual heat flux temperature sensor can be incorporated into an electronic device such that it contacts the skin of a user when the electronic device is worn by a user. Temperature measurements from the miniature dual heat flux temperature sensor can be displayed to the user, used by the electronic watch to perform various functions such as a health tracking, and/or combined with other sensor data. In some cases, when incorporated into an electronic device such as a wearable electronic device a miniature dual heat flux temperature sensor can estimate and track deep tissue temperatures of a user over a period of time such as hours, days, months, years, and so on. 
     These and other embodiments are discussed below with reference to  FIGS.  1 - 7   . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these Figures is for explanatory purposes only and should not be construed as limiting. 
       FIG.  1    illustrates an electronic device  100  that incorporates a miniature dual heat flux temperature sensing device  102 . The electronic device  100  is depicted as an electronic watch (e.g., a smart watch). The body of the watch is shown in phantom to illustrate that the temperature sensing device can be positioned within or partially within an internal chamber of the housing. The watch is one example embodiment of an electronic device and the concepts described herein may apply equally or by analogy to other electronic devices, including mobile phones (e.g., smartphones), tablet computers, notebook computers, head-mounted displays, digital media players (e.g., mp3 players), health-monitoring devices, other portable electronic devices, or the like. The electronic device  100  can incorporate the miniature dual heat flux temperature sensing device  102  as described herein. 
     The electronic device  100  may be worn by a user  101  and include one more sensors that determine a condition(s) of the user such as a body temperature, heart rate, position, direction of movement, and so on, and/or a condition of the environment such as a barometric pressure, air temperature, moisture level, and so on. Different sensors may be positioned at different locations on or within the electronic device  100  depending on operating requirements of a particular sensor, the condition being detected by the sensor, the design of the electronic device  100 , and so on. 
     The electronic device  100  can include the dual heat flux temperature sensors  102  that are configured to estimate a deep tissue temperature of the user  101  by measuring temperatures of the skin of the user  101 . The electronic device  100  can include a housing  103  and cover  104  coupled to the housing  103 . The cover  104  can be transparent and positioned over a display  106 . The housing  103 , the cover  104 , along with other components, may form a sealed internal chamber or volume of the electronic device  100 . The cover  104  can also define an input surface of the electronic device  100 . For example, as described herein, the electronic device  100  may include touch and/or force sensors that detect inputs applied to the cover  104 . The cover  104  may be formed from or include glass, sapphire, polymer, dielectric, or any other suitable material. 
     The display  106  can be positioned under the cover  104  and at least partially within the housing  103 . The display  106  can define an output region in which graphical outputs are displayed. Graphical outputs may include graphical user interfaces, user interface elements (e.g., buttons, sliders, etc.), text, lists, photographs, animations, videos, or the like. The display  106  can include a liquid-crystal display (LCD), organic light emitting diode (OLED) display, or any other suitable components or display technology. In some cases, the display  106  can output a graphical user interface with one or more graphical objects that display information collected from or derived from the pressure-sensing system. For example, the display  106  can output a current barometric pressure associated with the electronic device  100  or estimated altitude of the electronic device  100 . 
     The display  106  may include or be associated with touch sensors and/or force sensors that extend along the output region of the display and which may use any suitable sensing elements and/or sensing techniques. Using touch sensors, the electronic device  100  may detect touch inputs applied to the cover  104 , including detecting locations of touch inputs, motions of touch inputs (e.g., the speed, direction, or other parameters of a gesture applied to the cover  104 ), or the like. Using force sensors, the device  100  may detect amounts or magnitudes of force associated with touch events applied to the cover  104 . The touch and/or force sensors may detect various types of user inputs to control or modify the operation of the device, including taps, swipes, multiple finger inputs, single- or multiple-finger touch gestures, presses, and the like. Touch and/or force sensors usable with wearable electronic devices, such as the device  100 , are described below. 
     The electronic device  100  may also include a crown  108  having a cap, protruding portion, or component(s) or feature(s) (collectively referred to herein as a “body”) positioned along a side surface of the housing  103 . At least a portion of the crown  108  (such as the body) may protrude from, or otherwise be located outside, the housing  103 , and may define a generally circular shape or circular exterior surface. The exterior surface of the body of the crown  108  may be textured, knurled, grooved, or otherwise have features that may improve the tactile feel of the crown  108  and/or facilitate rotation sensing. 
     The crown  108  may facilitate a variety of potential interactions. For example, the crown  108  may be rotated by a user (e.g., the crown may receive rotational inputs). Rotational inputs of the crown  108  may zoom, scroll, rotate, or otherwise manipulate a user interface or other object displayed on the display  106  (among other possible functions). The crown  108  may also be translated or pressed (e.g., axially) by the user. Translational or axial inputs may select highlighted objects or icons, cause a user interface to return to a previous menu or display, or activate or deactivate functions (among other possible functions). In some cases, the device  100  may sense touch inputs or gestures applied to the crown  108 , such as a finger sliding along the body of the crown  108  (which may occur when the crown  108  is configured to not rotate) or a finger touching the body of the crown  108 . In such cases, sliding gestures may cause operations similar to the rotational inputs, and touches on an end face may cause operations similar to the translational inputs. As used herein, rotational inputs include both rotational movements of the crown (e.g., where the crown is free to rotate), as well as sliding inputs that are produced when a user slides a finger or object along the surface of a crown in a manner that resembles a rotation (e.g., where the crown is fixed and/or does not freely rotate). In some embodiments, rotating, translating, or otherwise moving the crown  108  initiates a pressure measurement by a pressure-sensing system (such as an external and/or internal pressure-sensing device) located on or within the electronic device  100 . In some cases, selecting an activity, requesting a location, specific movements of the user, and so on may also initiate pressure measurements by the pressures-sensing system. 
     The electronic device  100  may also include other inputs, switches, buttons, or the like. For example, the electronic device  100  includes a button  110 . The button  110  may be a movable button (as depicted) or a touch-sensitive region of the housing  103 . The button  110  may control various aspects of the electronic device  100 . For example, the button  110  may be used to select icons, items, or other objects displayed on the display  106 , to activate or deactivate functions (e.g., to silence an alarm or alert), or the like. 
     The electronic device  100  may include a band  112  coupled to the housing  103 . The band may be configured to couple the electronic device  100  to a user, such as to the user&#39;s arm or wrist. A portion of the band  112  may be received in a channel that extends along an internal side of the housing  103 , as described herein. The band  112  may be secure to the housing within the channel to maintain the band  112  to the housing  103 . 
       FIGS.  2 A and  2 B  illustrate top and bottom perspective views, respectively, of a temperature sensing device  200  that can be included in an electronic device. The temperature sensing device  200  can be an example of the miniature dual heat flux temperature sensing devices described herein such as dual heat flux temperature sensing device  102 . The temperature sensing device  200  can include a sensor body  202  that has a first section  204  having a first thickness (here, its height) and a second section  206  that has a second thickness (again, in this example its height) that is less than the first section  204 . The temperature sensing device  200  can also include a first set of temperature sensors  208  and  210  that are configured to measure a temperature difference across the first thickness of the first section  204 , and a second set of temperature sensors  212  and  214  that are configured to measure a temperature difference across the second thickness of the second section  206 . 
     In some embodiments, the first section  204  is a cylindrical body forming an inner portion of the sensor body  202  and the second section  206  is also a cylindrical body (or more specifically, a toroidal body) forming an outer portion of the sensor body  202 . The second section  206  can extend around the outside cylindrical surface of the first section  204 . In some cases, the first section  204  and the second sections  206  can be formed from a single homogenous material to form a continuous sensor body  202 . In other cases, the first section  204  and the second section  206  may be formed as separate bodies and joined together to form a single sensor body  202 . The sensor body  202  can also include one or more channels such as channels  203 ,  205  and  207 , which are located between the first section  204  and the second section  206 . The channels may be formed in the sensor body  202  such that a depth of the channel extends partially through a thickness of the sensor body  202 . Accordingly, the sensor body  202  can be a continuous and/or single structure that defines the first section  204 , the second section  206  and one or more channels positioned between the first and second sections  204 ,  206 . 
     The channels  203 ,  205  and  207  may be configured to reduce the heat transfer between the first section  204  and the second section  206 . The channels can contain air (or other gas) that has a higher resistance to heat flow (lower heat transfer rate) than the sensor body. In this regard, the first channel  203  can separate the first lower surface of the first section  204  from the second lower surface of the second section  206  to reduce heat between these portions of the sensor body  202 . In some cases, the sensor body  202  defines a single channel (e.g., first channel  203 ) positioned along a lower surface between the first section  204  and the second section  206 . In some embodiments, the sensors body can define additional channels between the first section  204  and the second section  206 . For example, the sensor body  202  can be formed to define a second channel  205  between the first and second sections  204  and  206 . In this regard, the sensor body  202  can have a third lower surface  216  that is positioned between the first lower surfaces of the first section  204  and second lower surface of the second section  206 . Additionally or alternatively, the sensor body  202  can be formed to define a third channel  207  that is positioned between the first upper surface of the first section  204 , and the second upper surface of the second section  206 . 
     As illustrated in  FIGS.  2 A and  2 B , the sensor body  202  can be radially symmetric about an axis  201  and the channels  203 ,  205  and/or  207  can extend in a circular configuration around the axis  201  (e.g., they may be ring-shaped). In other embodiments, the sensor body  202  can be formed in other configurations such as a square, or other polygon configurations. 
     As illustrated in  FIG.  2 B , a first temperature sensor  208  can be located on a first lower surface of the sensor body  202  corresponding to the first section  204 . As illustrated in  FIG.  2 A , a second temperature sensor  210  can be located on a first upper surface of the sensor body  202  also corresponding to the first section  204 . The first and second temperature sensors  208 ,  210  can form a first set of temperature sensors and be configured to measure temperatures of the sensor body  202  at the corresponding first lower surface and first upper surface. Also, as illustrated in  FIGS.  2 A and  2 B , a third temperature sensor  212  can be located on a second lower surface of the sensor body  202  corresponding to the second section  206 , and a fourth temperature sensor  214  can be located on a second upper surface also corresponding to the second section  206 . The third and fourth temperature sensors  212 ,  214  can form a second set of temperature sensors and be configured to measure temperatures of the sensor body  202  at the corresponding second lower surface and second upper surface. In some cases, additional temperature sensors can be positioned at various points on the sensor body  202 . For example, multiple sets of temperature sensors (not shown) can be positioned around the second section  206 , and may be used in coordination with the second set of temperature sensors  212 ,  214  to increase accuracy of temperature measurements at a periphery of the sensor body  202 . 
     In some embodiments, the temperature sensors  208  and  212  are positioned on the sensor body  202  such that they are flush with the surface of the sensor body  202 . Such a configuration may result in even heat transfer from the body to both of the temperature sensors  212 ,  214  and the sensor body  202 . In other embodiments, the temperature sensors  208  and  212  protrude from the sensor body  202  or are positioned on the sensor body  202  such that they are raised from the surface of the sensor body  202 . Such a configuration can help the temperature sensors  208  and  212  contact a skin of the user to obtain good heat transfer between the skin and the temperature sensors  208  and  212 . 
       FIG.  3    illustrates a cross-sectional view taken along section A-A of  FIG.  2 A  of a temperature sensing device  300 . The temperature sensing device  300  can include a sensor body  302 , which may be an example of the sensor bodies described herein (e.g., sensor body  202 ). The sensor body  302  can define a first section  304 , a second section  306 , and one or more channels  303 ,  305 ,  307 . The temperature sensing device  300  can also include a first temperature sensor  308 , a second temperature sensor  310 , a third temperature sensor  312 , and a fourth temperature sensor  314 , which may be examples of the temperature sensors described herein. 
     The sensor body  302  can be formed, machined, or otherwise shaped to define the first, second, and/or third channels  303 ,  305  and  307 . In some cases, a depth of the first channel  303  can extend from the first lower surface  311  of the first section  304  and toward to the first upper surface  313  of the first section  304 . The first channel  303  can contain air (or other gas), or other insulating material between the first section  304  and the second section  306 , that results in a thermal break that decreases the heat transfer rate (increases the thermal resistance) between the first section  304  and the second section  306 . In this regard, when the first lower surface  311  is placed on a skin of a user, heat transferred to the first section  304  from the user is at least partially isolated from the second section  306 . Accordingly, the first channel  303  at least partially thermally isolates the first section  304  from the second section  306  of the sensor body  302  such that the effect of heat flow occurring at the first section (from the first lower surface  311  to the first upper surface  313 ) on the second section  306  is reduced as compared to devices without a channel separating the lower surfaces. Similarly, the effect of heat flow occurring at the second section (from the second lower surface  315  to the second upper surface  317 ) on the first section  304  is reduce by the first channel  303 . 
     In some embodiments, a depth of the second channel  305  can extend from the second lower surface  315  and toward the second upper surface  317 . Similar to the first channel  303 , the second channel  305  can thermally isolate the first section  304  from the second section  306 . In some embodiments, the sensor body can include a single channel (e.g., first channel  303  or second channel  305 ). In other embodiments, the sensor body  302  can include multiple channels such as both the first channel  303  and the second channel  305 , which may result in greater thermal isolation between the first section  304  and the second section  306 . Additionally or alternatively, the sensor body  302  can include the third channel  307 , which can extend from the second upper surface  317  and toward the second lower surface  315 . 
       FIG.  4    illustrates a cross-sectional view taken along section A-A of  FIG.  2 A  showing an example temperature gradient across a temperature sensing device  400 . The temperature sensing device  400  can be an example of the temperatures sensing devices described herein (e.g., temperature sensing devices  102 ,  200 , and  300 ). The temperature sensing device  400  can include a sensor body  402  including a first section  404 , a second section  406 , and defining a first channel  403 , a second channel  405  and a third channel  407 .  FIG.  4    illustrates the temperature sensing device  400  placed on the skin  420  of a user  401  and being used to estimate a subsurface temperature  409  associated with deep tissue  421  of a user  401 .  FIG.  4    also illustrates an example heat gradient across the sensor body  402 , with larger circles representing higher temperatures. As shown in  FIG.  4   , the channels  403 ,  405  and  407  thermally isolate the first section  404  from the second section  406 . For example, the channels  403 ,  405  and  407  create a longer, serpentine path that heat has to travel to be transferred between the first section  404  and the second section  406 . 
     In some cases, the skin  420  of the user  401  is at a lower temperature than tissue  421  below the skin  420 . As used herein, the term “subsurface temperature”  409  refers to the temperature of tissue that is located below the skin surface  420 , for example tissue located below an epidermis layer of the skin. In some embodiments, the temperature sensing device  400  can measure a temperature at the skin  420  and use these measurements to estimate the subsurface temperature  409  of the user. 
     For example, the temperature sensing device  400  can measure a temperature across the thickness of the first section  404 , for example, by determining a first temperature difference between the first lower surface  411  and the first upper surface  413 . The temperature sensing device  400  can also measure a temperature across the thickness of the second section  406 , for example, by determining a second temperature difference between the second lower surface  415  and the second upper surface  417 . A different temperature between the first section  404  and the second section  406  can be used to estimate the subsurface temperature  409 . 
     By way of example, T 1  can be a first temperature measured at the first lower surface  411 , T 2  can be a second temperature measured at the second lower surface  415 , T 3  can be a third temperature measured at the first upper surface  413  and T 4  can be a fourth temperature measured at the second upper surface  417 . The following equation can be used to estimate the subsurface temperature  409  (T subsurface ): 
     
       
         
           
             
               T 
               Subsurface 
             
             = 
             
               
                 T 
                 1 
               
               + 
               
                 
                   
                     ( 
                     
                       
                         T 
                         1 
                       
                       - 
                       
                         T 
                         2 
                       
                     
                     ) 
                   
                   ⁢ 
                   
                     ( 
                     
                       
                         T 
                         1 
                       
                       - 
                       
                         T 
                         3 
                       
                     
                     ) 
                   
                 
                 
                   
                     K 
                     ⁡ 
                     
                       ( 
                       
                         
                           T 
                           2 
                         
                         - 
                         
                           T 
                           4 
                         
                       
                       ) 
                     
                   
                   - 
                   
                     ( 
                     
                       
                         T 
                         1 
                       
                       - 
                       
                         T 
                         3 
                       
                     
                     ) 
                   
                 
               
             
           
         
       
     
     Where K represent the ratio of the thermal conductivity between the thermal conductivity (K 1 ) of the first section  404  and the thermal conductivity (K 2 ) of the second section  406 , and can be determined using the following equation: 
     
       
         
           
             K 
             = 
             
               
                 K 
                 1 
               
               
                 K 
                 2 
               
             
           
         
       
     
     As illustrated in  FIG.  4   , the temperature sensing device  400  is operative to increase the unidirectional heat flow from the bottom surfaces  411  and  415  to the top surfaces  413  and  417  (e.g., heat flow perpendicular to the skin surface), and decrease heat flow between the first section  404  and the second section  406 . For example, thermally isolating the first section  404  from the second section  406 , as described herein, can result in a higher thermal gradient between these sections, which can increase the accuracy of the subsurface temperature measurement. 
       FIG.  5    illustrates a cross-sectional view taken along section A-A of  FIG.  2 A  of a temperature sensing device  500 . The temperature sensing device  500  can be an example of the temperature sensing device described herein (e.g., temperature sensing devices  102 ,  200 ,  300 , and  400 ), and include a sensor body  502  comprising a first section  504  and a second section  506 , as described herein. The sensor body  502  can define a first channel  503 , a second channel  505  and a third channel  507 , which can be examples of the channels described herein. The temperature sensing device  500  can also include a first temperature sensor  508 , a second temperature sensor  510 , a third temperature sensor  512  and a fourth temperature sensor  514 . 
     In some embodiments, the temperature sensing device  500  can be positioned on and/or coupled to a substrate  509 , and the substrate  509  may be positioned against a skin of a user. In some cases, the substrate  509  can be a portion of an electronic device, for example a housing element, such as a wall, cover or peripheral structure of the device that positions the temperature sensing device  500  in proximity to a skin surface of a user. In some examples, the substrate can be a conductive material such as metal, plastic, composite material or any other suitable material. 
     In some embodiments, the temperature sensors  508 ,  510 ,  512 , and  514  can include thin film temperature sensors such as a thin film resistance temperature detector (RTD), negative thermal coefficient (NTC) temperature sensors, thermocouples, thermopiles, or other suitable temperature sensing devices. In some cases, the temperature sensing device can include additional temperature sensors. For example, additional temperature sensors could be positioned around the upper and lower surfaces of the second section  506 . In some cases, temperature measurements from various sensors can be combined, averaged, compared, or otherwise modified, and used to perform the subsurface temperature estimation techniques described herein. 
     In some embodiments, one or more of the channels  503 ,  505 , and  507  can contain an insulating material. As used herein, “an insulating material” refers to materials that have a lower thermal conductivity (higher resistance to heat flow) than the material of the sensor body  502 . For example, the first channel  503  can contain a first insulating material  520 , the second channel  505  can contain a second insulting material  522 , and the third channel  507  can contain a third insulating material  524 . The first, second and third insulating materials  520 ,  522 , and  524  can be the same or different. Examples of insulating materials can include air (as described herein); other gases; a vacuum where air is removed from the channels  503 ,  505  and/or  507 ; materials such as fiber glass, mineral wool, cellulose, and so on. 
       FIGS.  6 A- 6 D  show cross-sectional views taken along line A-A of  FIG.  2 A  of example temperature sensing devices  600 . The temperature sensing devices  600  can be examples of the temperature sensing device described herein (e.g., temperature sensing devices  102 ,  200 ,  300 ,  400 , and  500 ), and include a sensor body  602  comprising a first section  504  and a second section  506 . The sensor body  602  can define a first channel  603 , a second channel  605  and a third channel  607 , which can be examples of the channels described herein. The temperature sensing device  600  can also include temperature sensors as described herein. 
     In the example shown in  FIG.  6 A , the sensor body  602  can define a third section  608  that connects the first section  604  to the second section  606 . The third section  608  can be offset from the lower surfaces  611  and  615  such that when the temperature sensing device  600  is placed against a user, the first and second surfaces  611  and  615  contact the user or a substrate (e.g., substrate  509 ), while the third section  608  does not contact the user or the substrate. This configuration may reduce heat transfer from the user to the third section  608 , which can reduce heat flow that occurs between the first section  604  and the second section  606 . 
     In the example shown in  FIG.  6 B , the temperature sensing device  600  can include an insulating material  624  within one or more of the channels  603 ,  605  and  607 . For example, The sensor body  602  can define a raised third section  608  that connects the first and second sections  604  and  606  as described in reference to  FIG.  6 A . In some cases, a first insulating material  624   a  can be positioned within the first channel  603 , the second channel  605  and space created by the raised third section  608 . In some cases, the third channel  607  can also contain a second insulating material  624   b , which can be the same or different as the first insulating material  624   a . The insulating materials  624  can have lower heat transfer rate than the sensor body  602 . In some cases, the insulating materials  624  can include air, a vacuum, foams or other lower resistance materials such glass, plastics, ceramics, and so on. 
     In the example shown in  FIG.  6 C , the temperature sensing device  600  can include an insulating material  624  that is positioned between the first and second sections  604  and  606 , and separates the first section  604  from the second section  606 . In some embodiments, the insulating material  624  can couple the first section  604  to the second section  606 . In the example shown in  FIG.  6 C , the insulating material  624  can extend to the height of the second section  606 . The insulating material  624  can include insulating materials as described herein, such as foams, ceramics, glasses, plastics, composite materials, and so on that have a lower heat transfer rate than the material forming the first and second sections  604  and  606 . 
     In the example shown in  FIG.  6 D , the temperature sensing device  600  can include an insulating material  624  that is positioned between the first and second sections  604  and  606 , and separates the first section  604  from the second section  606 . The insulating material  624  can extend to the height of the first section  604 , which may increase unidirectional heat flux by insulating the first section  604  from the surrounding environment. In other cases, the temperature sensing device  600  can include a second insulating material  626  that surrounds the second section  606 . Additionally or alternatively, the insulating materials can fully or partially encapsulate the temperature sensing device  600 , or selectively cover different portions of the temperature sensing device, which may be configured to increase the unidirectional heat flux across the first section  604  and the second section  606  and decrease heat transfer between the first and second sections  604  and  606 . 
       FIG.  7    is a block diagram illustrating an example electronic device  700 , which can take the form of any of the electronic devices incorporating a dual heat flux temperature sensing device as described with reference to  FIGS.  1 - 5   . The optical device can include a processor  702 , an input/output (I/O) mechanism  704  (e.g., an input/output device, such as a touch screen, crown or button, input/output port, or haptic interface), one or more temperature sensors  706 , memory  708 , other sensors  710  (e.g., an optical sensing system, barometric pressure sensors, etc.), and a power source  712  (e.g., a rechargeable battery). The processor  702  can control some or all of the operations of the electronic device  700 . The processor  702  can communicate, either directly or indirectly, with some or all of the components of the electronic device  700 . For example, a system bus or other communication mechanism  714  can provide communication between the processor  702 , the I/O mechanism  704 , the dual heat flux temperature sensing device  706 , the memory  708 , the sensors  710 , and the power source  712 . 
     The processor  702  can be implemented as any electronic device capable of processing, receiving, or transmitting data or instructions. For example, the processor  702  can be a microprocessor, a central processing unit (CPU), an application-specific integrated circuit (ASIC), a digital signal processor (DSP), or combinations of such devices. As described herein, the term “processor” is meant to encompass a single processor or processing unit, multiple processors, multiple processing units, or other suitable computing element or elements. 
     It should be noted that the components of the electronic device  700  can be controlled by multiple processors. For example, select components of the electronic device  700  (e.g., a sensor  710 ) may be controlled by a first processor and other components of the electronic device  700  (e.g., the temperature sensing device  706 ) may be controlled by a second processor, where the first and second processors may or may not be in communication with each other. 
     The I/O mechanism  704  can transmit and/or receive data from a user or another electronic device. An I/O device can include a display, a touch-sensing input surface, one or more buttons (e.g., a graphical user interface “home” button), one or more cameras, one or more microphones or speakers, one or more ports, such as a microphone port, and/or a keyboard. Additionally or alternatively, an I/O device or port can transmit electronic signals via a communications network, such as a wireless and/or wired network connection. Examples of wireless and wired network connections include, but are not limited to, cellular, Wi-Fi, Bluetooth, IR, and Ethernet connections. 
     The temperature sensing device  706  can be any of, or include a combination of features of the dual heat flux temperature sensing devices described herein, such as temperature sensing devices  100 ,  200 ,  300 ,  400 ,  500  or  600 . In some cases, the electronic device  700  can include multiple temperature sensing devices  706  that are positioned at various locations of the electronic device  700 . For example, one or more temperature sensing devices  706  can be configured to estimate a subsurface temperature of an external subject such as a deep tissue temperature of a user. Additionally or alternatively, one or more temperature sensing devices  706  can be operative to measure a subsurface temperature of one or more internal components, such as a processor (e.g., processor  702 ), memory (e.g., memory  708 ), and so on. 
     The memory  708  can store electronic data that can be used by the electronic device  700 . For example, the memory  708  can store electrical data or content such as, for example, audio and video files, documents and applications, device settings and user preferences, timing signals, control signals, and data structures or databases. The memory  708  can be configured as any type of memory. By way of example only, the memory  708  can be implemented as random access memory, read-only memory, Flash memory, removable memory, other types of storage elements, or combinations of such devices. 
     The electronic device  700  may also include one or more sensors  710  positioned almost anywhere on the electronic device  700 . The sensor(s)  710  can be configured to sense one or more type of parameters, such as but not limited to, pressure, light, touch, heat, movement, relative motion, biometric data (e.g., biological parameters), and so on. For example, the sensor(s)  710  may include a heat sensor, a position sensor, a light or optical sensor, an accelerometer, a pressure transducer, a gyroscope, a magnetometer, a health monitoring sensor, and so on. Additionally, the one or more sensors  710  can utilize any suitable sensing technology, including, but not limited to, capacitive, ultrasonic, resistive, optical, ultrasound, piezoelectric, and thermal sensing technology. 
     The power source  712  can be implemented with any device capable of providing energy to the electronic device  700 . For example, the power source  712  may be one or more batteries or rechargeable batteries. Additionally or alternatively, the power source  712  can be a power connector or power cord that connects the electronic device  700  to another power source, such as a wall outlet. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Metadata:
Filing Date: 20200630
Publication Date: 20230425
Grant Date: 20230425
Priority Date: 20200630
Inventors: RAHMANI, HELIA
MINERVINI, ANTHONY D.
HUANG, WANFENG
CLEMENTS, JAMES C.
YU, Jiandong
ZENG, ZIJING
OGATA, CHARLEY T.
Assignee: APPLE INC
CPC Classifications: [{"code": "G01K1/026", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01K3/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01K7/427", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01K13/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/01", "inventive": false, "first": false, "tree": "[]"}, {"code": "G01K13/20", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01K7/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01K7/427", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01K1/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01K13/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01K7/427", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01K3/08", "inventive": true, "first": true, "tree": "[]"}, {"code": "G01K7/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01K1/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "G01K1/026", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/01", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 79031728