Patent Publication Number: US-2019175096-A1

Title: Wearable thermometer patch for monitoring wound healing

Description:
BACKGROUND OF THE INVENTION 
     The present application relates to wearable electronic devices, and in particular, to wearable thermometer patches that can measure human skin temperatures near wounds. 
     Ambulatory temperature monitoring of local skin are of great importance for wound healing. Local skin temperature can change noticeably due to local inflammation and perfusion. During the healing process of the wound, local temperature becomes higher than surroundings, and then gradually drops. If temperature elevation is observed for a longer duration than expected, it indicates extended inflammation and possible infection, which impacts normal healing process, so appropriate anti-infective agents or additional management may be needed. 
     Past researches have shown that skin temperatures can be measured by image sensors that are sensitive in the IR spectral range. This type of equipment is normally bulky and cannot be easily carried by users. Their measurements also require users to stop their other daily activities. In addition, it requires advanced equipment or algorithmic processing of the data. 
     Products for monitoring wound healing are not known in the market. A smart suture developed by Professor John Roger has been tested to monitor wound infection on a rat model. However, suture is not necessary or suitable for all wounds. 
     There is therefore a long-felt need for a convenient, portable, low-cost, and noninvasive device that can monitor wound healing on human skin without affecting user&#39;s daily activities, and suitable for different types of wounds. 
     SUMMARY OF THE INVENTION 
     The presently disclosure attempts to provide a convenient and portable solution for monitoring the process of wound healing on human skin. The presently disclosed wearable wireless thermometer patch that can be attached to human skin near a wound to conduct temperature measurements, which can continuously monitor the healing progress and notify the doctor promptly for abnormal healing process. The disclosed wearable wireless thermometer patch is convenient to wear, noninvasive, low-cost, and suitable for different types of wounds. The disclosed wearable wireless thermometer patch allows the user to conduct his or her usual daily activities. 
     In the presently disclosed wearable wireless thermometer patch is flexible, breathable, and stretchable, which are thus comfortable to wear. The disclosed wearable thermometer patches are capable wireless communication with little interference from users&#39; skins. 
     In one general aspect, the present invention relates to a wearable thermometer patch for monitoring healing of a wound on a user&#39;s skin, including: a circuit substrate that includes an electric circuit; a first temperature probe unit that includes a first temperature sensor in electric connection with the electric circuit in the circuit substrate, wherein the first temperature probe unit is located at a first position along a first direction; and a second temperature probe unit comprising a second temperature sensor in electric connection with the electric circuit in the circuit substrate, wherein the second temperature probe unit is located at a second position along the first direction, wherein the wearable thermometer patch is to be attached near a wound on a user&#39;s skin with the first direction is toward or away from the wound, wherein the first temperature probe unit and the second temperature probe unit can measure temperature values at different distances from the wound on the user&#39;s skin, wherein a temperature gradient is calculated based on the temperature values at the different distances. 
     Implementations of the system may include one or more of the following. The first direction can be substantially perpendicular to the wound on the user&#39;s skin. The wearable thermometer patch can further include a third temperature probe unit comprising a third temperature sensor in electric connection with the electric circuit, wherein the third temperature probe unit is located at a third position along the first direction, wherein the temperature gradient is calculated further based on temperature values measured by the third temperature probe unit. The first temperature probe unit, the second temperature probe unit, and the third temperature probe unit can be positioned along a substantially straight line in the first direction. The wearable thermometer patch can further include a lower layer below the circuit substrate, wherein the circuit substrate and the lower layer include through holes in which the first temperature probe unit and the second temperature probe unit are respectively mounted, wherein the first temperature probe unit and the second temperature probe unit include portions respectively can be in contact with the user&#39;s skin. The wearable thermometer patch can further include an adhesive material under the lower layer and configured to bond the lower layer to the user&#39;s skin. The first temperature probe unit can include a thermally conductive cup having a bottom portion that can be in contact with the user&#39;s skin, wherein the first temperature sensor is placed inside and in thermal conduction with the thermally conductive cup. The wearable thermometer patch can further include a semiconductor chip mounted on the circuit substrate and in electric connection with the electric circuit, wherein the semiconductor chip can receive a first electrical signal from the first temperature sensor in response to a first measured skin temperature at the first position, wherein the semiconductor chip can receive a second electrical signal from the second temperature sensor in response to a second measured skin temperature at the second position. The wearable thermometer patch can further include an antenna mounted on the circuit substrate and in electric connection with the semiconductor chip, wherein the antenna can wirelessly send temperature measurement data or the temperature gradient to a control device. The temperature gradient can be calculated on the control device based on the first measured skin temperature and the a second measured skin temperature. The semiconductor chip can calculate the temperature gradient based on the first measured skin temperature and the a second measured skin temperature. The wearable thermometer patch can further include a treatment portion that can apply heat, an electrical signal, or a force or a pressure to user&#39;s skin to assist healing of the wound. The wearable thermometer patch can further include an elastic layer on the circuit substrate, the first temperature probe unit, and the second temperature probe unit. 
     In another general aspect, the present invention relates to a portable system for monitoring healing of a wound on a user&#39;s skin, including: a wearable thermometer patch attached near a wound on a user&#39;s skin, comprising: a circuit substrate comprising an electric circuit; a first temperature probe unit comprising a first temperature sensor in electric connection with the electric circuit in the circuit substrate, wherein the first temperature probe unit is located at a first position along a first direction; and a second temperature probe unit comprising a second temperature sensor in electric connection with the electric circuit in the circuit substrate, wherein the second temperature probe unit is located at a second position along the first direction, wherein the wearable thermometer patch is so positioned that the first direction is toward or away from the wound, wherein the first temperature probe unit and the second temperature probe unit that can measure temperature values at different distances from the wound on the user&#39;s skin; and a control device that can control temperature measurements by the first temperature probe unit and the second temperature probe unit, wherein a temperature gradient is calculated based on the temperature values at the different distances. 
     Implementations of the system may include one or more of the following. The wearable thermometer patch can further include an antenna mounted on the circuit substrate and in electric connection with the semiconductor chip, wherein the antenna can wirelessly send temperature measurement data or the temperature gradient to the control device. The control device can calculate the temperature gradient based on the first measured skin temperature and the second measured skin temperature. The wearable thermometer patch further can include a semiconductor chip mounted on the circuit substrate and in electric connection with the electric circuit, wherein the semiconductor chip can receive a first electrical signal from the first temperature sensor in response to a first measured skin temperature at the first position, wherein the semiconductor chip can receive a second electrical signal from the second temperature sensor in response to a second measured skin temperature at the second position, wherein the semiconductor chip can calculate the temperature gradient based on the first measured skin temperature and the a second measured skin temperature. The first direction can be substantially perpendicular to the wound on the user&#39;s skin. The wearable thermometer patch can further include a third temperature probe unit comprising a third temperature sensor in electric connection with the electric circuit, wherein the third temperature probe unit is located at a third position along the first direction, wherein the temperature gradient is calculated further based on temperature values measured by the third temperature probe unit. 
     In another general aspect, the present invention relates to a portable system for monitoring healing of a wound on a user&#39;s skin, including: a plurality of wearable thermometer patches attached near a wound on a user&#39;s skin, wherein at least one of plurality of wearable thermometer patches includes: a circuit substrate comprising an electric circuit; multiple temperature probe units each comprising a temperature sensor in electric connection with the electric circuit in the circuit substrate, wherein the multiple temperature probe unit are located at different positions along a first direction, wherein the wearable thermometer patch is so positioned that the first direction is toward or away from the wound, wherein the multiple temperature probe units can measure temperature values at different distances from the wound on the user&#39;s skin; and a control device that can control temperature measurements by the multiple temperature probe units, wherein a temperature gradient can be calculated based on the temperature values at the different distances from the wound at the at least one of the plurality of wearable thermometer patches. 
     These and other aspects, their implementations and other features are described in detail in the drawings, the descriptIon and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates the usage of a wearable thermometer patch attached to a user&#39;s skin. 
         FIG. 2  illustrates a wearable thermometer patch properly positioned next to a wound on a user&#39;s skin in accordance with some embodiments of the present invention. 
         FIG. 3  is a system block diagram for a wireless control device in wireless communications of the wearable thermometer patch in accordance with some embodiments of the present invention. 
         FIG. 4  is a cross-sectional view of a wearable thermometer patch for monitoring wound healing in accordance with some embodiments of the present invention. 
         FIG. 5  is a top view of the wearable thermometer patch in  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1 and 2 , a system  100  includes at least one wearable thermometer patch  200  and a wireless control device  130 . The wearable thermometer patch  200  is attached to the skin  120  of a user for measuring skin temperature and optionally other body vital signs. The wearable thermometer patch  200  can be placed near a wound  125  on the skin  120  to monitor the healing process and progress of the wound  125 . In the present disclosure, the term “wearable thermometer patch” can also be referred to as “wearable sticker”, “wearable tag”, or “wearable band”, etc. The wearable thermometer patch  200  can be attached to the skin with adhesives or held to be in contact with the skin by a band wrapped around a user&#39;s arm, ankle, or a leg. 
     Referring to  FIGS. 1 and 3 , the wireless control device  130  can wirelessly exchange data with the wearable thermometer patch  200 . The wireless communications can be conducted using Wi-Fi, Bluetooth, Zigbee, and other wireless communication technologies and protocols. The wireless control device  130  can be a portable mobile device, which a user can carry with him or her. The wireless control device  130  can also be a stationary device that can be placed at home or office where the user may stay for an extended period. The portable mobile device can be implemented with specialized hardware and software units built in a smart phone, a tablet computer (including devices such as iPod), or a dedicated health or sport monitoring device. The wireless control device  130  can be in communication with a network server in which a user account is stored for the user. 
     In some embodiments, the wearable thermometer patch  200  can conduct one or more types of measurements on the user&#39; skin or body. In addition to measuring skin temperature, the wearable thermometer patch  200  can include sensors that sense a variety of signals such as electric voltage, galvanic skin response, blood pressure, heart rate, force, acceleration, blood oxygen level, blood glucose level, etc. The wearable thermometer patch  200  can also include a treatment portion for applying treatments to the user&#39;s skin or body. The treatment portion can apply electrical signals, heat, and sometimes force or pressure to user&#39;s body to assist the wound healing process. Details of wearable patches for conducting measurements and treatments are disclosed in commonly assigned co-pending U.S. patent application Ser. No. 15/472,641 titled “Multi-purpose wearable patch for measurement and treatment”, filed Mar. 29, 2017, the disclosure of which is incorporated herein by reference. 
     The wireless control device  130  includes a wireless communication module  140  that can wirelessly communicate with the wearable thermometer patches ( 200  in  FIG. 1 ) using above described wireless technologies. The wireless control device  130  includes a measurement controller  150  that controls the wireless communication module  140  to transmit measurement control signals to wearable thermometer patches ( 200  in  FIGS. 1 and 4 ). The measurement controller  150  can vary parameters of the measurements by the wearable thermometer patches. Such measurement parameters can include types, timing, frequencies, durations of measurements, coordination between measurements of the same of different wearable thermometer patches, and coordination between measurements and treatments by the wearable thermometer patches. A measurement data storage  155  stores the measurement data obtained by the wearable thermometer patch  200 . 
     The wireless control device  130  can also includes a treatment controller  160  that can control the treatment functions of the wearable thermometer patches based on a treatment plan stored in the treatment plan storage  165 . The treatment controller  160  can control the wireless communication module  140  to transmit treatment control signals to wearable thermometer patch  200 . A treatment plan can define types, timing, frequencies, amplitude or power, durations of treatments, coordination between treatments of the same or different wearable thermometer patches, and coordination between treatments and measurements by the wearable thermometer patches. 
     Still referring to  FIGS. 1 and 3 , the wireless control device  130  can include a mode controller  170  that can set the wearable thermometer patches in measurement modes and/or treatment modes, or a combination thereof by controlling the treatment unit and the sensing unit. Some treatment and measurements can be conducted in parallel, but some should be implemented in separate time periods. In some applications, a portion of the wearable thermometer patches  200  applies treatments while another portion of the wearable thermometer patches  200  conducts measurements. The coordination between measurement and treatment modes is controlled by the mode controller  170 . A user data storage  175  stores user data such as user&#39;s weight, height, bone density, historic range for blood pressure, heart beat, body temperature, daily patterns of exercises and rests by the user, sickness or symptoms suffered by the user, etc. In some embodiments, as described below, personalized medical treatment can be applied, sometimes dynamically, based on such user data and physician&#39;s prescription. An intelligent analyzer  180  can process and analyze the measurement data from different wearable thermometer patches in reference to the measurement data (in  155 ), the treatment plan (in  165 ), and user data (in  175 ). 
     Referring to  FIG. 4 , the wearable thermometer patch  200  includes a flexible circuit substrate  410  and a lower layer  420  under the flexible circuit substrate  410 . The lower layer  420  is formed by a soft material such as a perforated polymer material, which can increase comfort when it is in contact with user&#39;s skin. Suitable materials for the perforated polymer material include soft materials such as Polyurethane. The flexible circuit substrate  410  and the lower layer  420  include multiple through holes  415 - 417  and temperature sensor units  421 - 423  respectively positioned in the through holes  415 - 417 . The temperature sensor units  421 - 423  are positioned along the x direction. The lower layer  420  is bonded to the bottom surface of the flexible circuit substrate  410  using an adhesive material. 
     A semiconductor chip  220 , a battery  435 , an antenna  440 , a memory  450 , and bonding pads  445  are mounted or formed on the upper surface of the flexible circuit substrate  410 . An electric circuit (not shown) is embedded in or formed on flexible circuit substrate  410 . The temperature sensor units  421 - 423 , the semiconductor chip  430 , the battery  435 , the antenna  440 , the bonding pads  445 , and the memory  450  are connected with the electric circuit in the flexible circuit substrate  410 . The battery  435  powers the semiconductor chip  430 , the electric circuit, and possibly the temperature sensor units  421 - 423 . The flexible circuit substrate  410  can be made of polymeric materials and built in with the electric circuit that connects the semiconductor chip  430 , the battery  435 , the antenna  440 , the bonding pads  445 , and the memory  450 . 
     In some embodiments, the temperature sensor units  421 ,  422 , or  423  can include a thermally conductive cup made of a thermally conductive metallic or alloy material such as copper, stainless steel, ceramic or carbide composite materials. A temperature sensor can be attached to and in thermal conduction with an inner surface near the bottom of the thermally conductive cup. The temperature sensor can be implemented, for example, by a Thermistor, a Resistor Temperature Detector, or a Thermocouple. An adhesive material is applied to a lower surface of the lower layer  420  to attach it to the user&#39;s skin. The temperature sensor units  421 - 423  are thus in tight contact with a user&#39;s skin for the accurate temperature measurement of the user&#39;s skin. Additionally, the disclosed wearable wireless thermometer patch can include double temperature sensors for correct measurements of human skin temperature. Using double temperature sensors, the temperature can be easily calculated from the Fourier&#39;s Law at the thermal equilibrium status, which is independent of the ambient temperature changes. 
     Further details of wearable thermometer patches are disclosed in the commonly assigned co-pending U.S. patent application Ser. No. 15/224,121 titled “Wearable thermometer patch for accurate measurement of human skin temperature”, filed Jul. 29, 2016, and the commonly assigned co-pending U.S. patent application Ser. No. 15/590,657 titled “A wearable thermometer patch capable of measuring human skin temperature at high duty cycle”, filed May 9, 2017, the disclosures of which are incorporated herein by reference. 
     When the bottom portions of the temperature sensor units  421 ,  422 , or  423  are in contact with a user&#39;s skin, heat is effectively transferred from the user&#39;s skin to the temperature sensors. The temperature sensor units  421 ,  422 , or  423  can send temperature sensing electrical signals to the electric circuit and the semiconductor chip  430 . The semiconductor chip  430  processes the electrical signal and outputs another electrical signal, which enables the antenna  440  to transmit a wireless signal to send measurement data to the wireless control device  130 . 
     When the wearable thermometer patch  200  is worn by the user, the antenna  440  is separated from the user&#39;s skin by the flexible circuit substrate  410  and the lower layer  420 , which minimizes the shielding of the user&#39;s body on the transmissions of wireless signals by the antenna  440 . 
     An elastic layer  480  is bonded onto the upper surface of the flexible circuit substrate  410  by an adhesive material. Alternatively, the elastic layer  480  can directly be molded onto the flexible circuit substrate  410  without using a bonding material. The elastic layer  480  includes recesses on the underside to define cavities to contain the antenna  440 , the battery  435 , and the semiconductor chip  430 . The elastic layer  480  also includes holes to allow moisture and sweat from the user&#39;s skin to diffuse to the ambient environment, which enhances user&#39;s comfort and strength of attachment of the wearable thermometer patch  200  to the user&#39;s skin  120 . 
     The elastic layer  480  can be made of a non-conductive material such as an elastomeric material or a viscoelastic polymeric material having low Young&#39;s modulus and high failure strain. In some embodiments, the elastic layer  480  has a Young&#39;s Modulus &lt;0.3 Gpa. In some cases, the elastic layer  480  and can have Young&#39;s Modulus &lt;0.1 Gpa to provide enhanced flexibility and tackability. Materials suitable for the elastic layer  480  include elastomers, viscoelastic polymers, such as silicone, silicone rubber, and medical grade polyurethane that is a transparent medical dressing used to cover and protect wounds with breathability and conformation to skin. 
     Referring to  FIGS. 2 and 4 , the temperature sensor units  421 ,  422 , and  423  are displaced at different positions along the x direction. The x direction is toward or away from the wound  125 . In one implementation, the temperature sensor units  421 ,  422 , and  423  are positioned substantially along a straight line. In some embodiments, the straight line can be substantially perpendicular to the wound  125 . In other implementations, for purpose of efficient packing, for example, the temperature sensor units  421 ,  422 , or  423  are disposed in a triangular form but still having different displacement positions along the x direction. In operation, the wearable thermometer patch  200  is placed on the skin  120  in such an orientation that the temperature sensor units  421 ,  422 , and  423  are positioned at different distances from the wound  125 . In one implementation, the wearable thermometer patch  200  is oriented with the associated x direction aligned toward or away from the wound  125 . The x direction can be aligned substantially perpendicular to the wound  125 . Thus, the temperature sensor units  421 ,  422 , and  423  can measure user&#39;s skin temperatures at different locations near the wound  125  during the healing process. 
     Referring to  FIGS. 2-4 , skin temperatures can be measured periodically or continuously by the temperature sensor units  421 ,  422 , and  423  at skin locations at different distances from the wound  125 . The control data for the temperature measurements can be stored in the memory  450 . The temperature measurement data are sent to and recorded in the measurement data storage  155  in the wireless control device  130 . The local skin temperatures at different locations measured by the temperature sensor units  421 ,  422 , and  423  can be stored in the memory  450  and are used to calculate a temperature gradient as a function of the distance from the wound  125 . The calculation can be conducted by firmware on the wearable thermometer patch  200  or software on the wireless control device  130 . During the healing process, the temperature at a skin location closer to the wound is higher than that at a skin location further away from the wound, that is, the temperature gradient is positive toward the wound. The temperature gradient will gradually decrease to below a threshold (reflecting natural skin temperature variations) as the wound heals to a complete recovery. 
     The treatment plan storage  165  can store a normal range for the temperature gradient as a function of healing time for the skin temperatures near a wound. If the intelligent analyzer  190  determines that the calculated temperature gradient based on the measured temperature data is not within a normal range at a specific healing time, the wireless control device  130  can send out an alert to the user or a medical professional. The treatment control data can be stored in the memory  450 . 
     In some embodiments, a second wearable thermometer patch can be attached to a similar skin location on the opposite side of the user body. Similar to the description above, the second wearable thermometer is so positioned that its associated x-direction is substantially perpendicular to the wound. Temperatures measured by the different temperature sensing units in this wearable thermometer patch can be used to calculate a baseline temperature gradient, which can be used to set the alert threshold. 
     The wearable thermometer patch  200  can operate individually, or a group of wearable thermometer patches  200  can provide certain desired treatment or measurement. For example, multiple wearable thermometer patches  200  can be attached at locations on the opposite sides or several different sides of the wound  215 , which can provide more accurate and comprehensive temperature monitoring around the wound  215 . Furthermore, one of multiple wearable thermometer patches  200  can be placed in a symmetric skin position with no wound to provide live reference temperature data and comparison temperature gradient. For example, if the left leg has a wound, in addition to one or more wearable thermometer patches  200  dedicated to measure temperature around the wound  215 , one or more wearable thermometer patches  200  can be attached to the symmetric positions on the right leg to provide temperature measurements and comparative temperature gradients. 
     The wearable thermometer patch  200  can also include a treatment portion to assist the wound healing process. The treatment portion can include heaters that can produce heat in target areas near the wound, or electromechanical actuators can produce electric or mechanical signals around the wound. The treatment signals are often applied in pulses. The treatment of wound is under the control of a treatment plan stored in the treatment plan storage  165  in the wireless control device  130 . Using the measurement data and optionally historic user data, the intelligent analyzer  180  identifies improvement, issues, and risks in the user based on the measurement data to generate an analysis result, which could lead to timely reporting to the user or a central server, timely treatment, and/or improvement in the existing treatment. A portion of the analysis functions can be accomplished by a network server in communication with the wireless control device  130 . Based on the analysis result, the treatment controller  160  can vary a type (e.g. heat or electric voltage), timing, a frequency, or duration of the treatment field in the user&#39;s body by the wearable thermometer patches. 
     The mode controller  170  plays a particular important role in dynamic treatments and dynamic measurements. The mode controller  170  can mobilize the treatment units to switch on a treatment mode in response to measurement data collected by the sensing units. Conversely, the mode controller  170  can mobilize sensing units and switch on measurement modes in the wearable thermometer patches in response to treatments applied to the user by the treatment units in the wearable thermometer patches. 
     Details of wearable patches for conducting measurements and treatments by one or a group of wearable sensors are disclosed in the commonly assigned co-pending U.S. patent application Ser. No. 15/649,008 titled “A system of networked wearable patches for measurement and treatment”, filed Jul. 13, 2017, the disclosure of which is incorporated herein by reference. 
     The disclosed wearable thermometer patches have one or more of the following advantages. The disclosed wearable thermometer patch is stretchable, compliant, durable, conforming, and comfortable to wear by user&#39;s skin. The disclosed wearable thermometer patch is noninvasive and can be generically applied to monitor healing of different types of wounds. The disclosed wearable thermometer patch is capable of maximum continuous monitoring of user&#39;s temperature during the wound healing process. The measurement data can also be wirelessly communicated with external devices, which allows wound healing to be monitored in real time. The disclosed wearable thermometer patch can also provide some treatments to help the recovery of the wound and functions nearby. The disclosed wearable thermometer can also have a disposable and a reusable part to make wound healing extremely cost-effective. 
     The disclosed wearable thermometer patches can also include electronic components such as the semiconductor chips, resistors, capacitors, inductors, diodes (including for example photo sensitive and light emitting types), other types of sensors, transistors, amplifiers. The sensors can also measure temperature, acceleration and movements, and chemical or biological substances. The electronic components can also include electromechanical actuators, chemical injectors, etc. The semiconductor chips can perform communications, logic, signal or data processing, control, calibration, status report, diagnostics, and other functions. 
     While this document contains many specifics, these should not be construed as limitations on the scope of an invention that is claimed or of what may be claimed, but rather as descriptions of features specific to particular embodiments. Certain features that are described in this document in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can be excised from the combination in some cases, and the claimed combination may be directed to a sub-combination or a variation of a sub-combination. 
     Only a few examples and implementations are described. Other implementations, variations, modifications and enhancements to the described examples and implementations may be made without deviating from the spirit of the present invention.