Temperature sensor for tracking body temperature based on printable nanomaterial thermistor

Patent metadata

Field	Value
Publication number	US-10034609-B2
Application number	US-201514932998-A
Country	US
Kind code	B2
Filing date	Nov 5, 2015
Priority date	Nov 5, 2015
Publication date	Jul 31, 2018
Grant date	Jul 31, 2018

Abstract

Provided are wireless temperature sensors. A temperature sensor with a flexible, large-area printed thermistor can include an negative temperature coefficient (NTC) thermistor for temperature sensing, a control circuitry for electrically connecting with the NTC thermistor and obtaining the temperature sensed by the NTC thermistor, a power source for providing power supply to the NTC thermistor and the control circuitry, and a frame element for supporting the NTC thermistor, the control circuitry and the power source, where the frame element is at least partially thermally insulated to establish thermal equilibrium within the temperature sensor. The temperature sensor can sense the temperature in a fast and accurate way due to fast thermal equilibrium established within the sensor.

First claim

The invention claimed is:

1. A temperature sensor based on printable thermistor, comprising:
a negative temperature coefficient (NTC) thermistor for temperature sensing, which comprises a substrate, a Si—C film printed on the substrate, and electrodes printed on the substrate for connecting the Si—C film with a control circuitry; wherein the NTC thermistor further comprises a first laminate and a second laminate; the first laminate is directly arranged on the Si—C film and the electrodes and is configured to improve thermal curing for the NTC thermistor; the second laminate is arranged on one side of the first laminate opposite to the Si—C film and the electrodes and is configured to prevent moisture from penetrating into the NTC thermistor;
the control circuitry which electrically connects with the NTC thermistor and operates for obtaining the temperature sensed by the NTC thermistor;
a power source for providing power supply to the NTC thermistor and the control circuitry; and
a frame element for supporting the NTC thermistor, the control circuitry and the power source; wherein the frame element is at least partially thermally insulated to establish thermal equilibrium within the temperature sensor.

2. The temperature sensor of claim 1 , wherein the first laminate has a water vapor transmission rate (WVTR) of 1-100 gram/m 2 /day and the second laminate has a WVTR of below 0.1 gram/m 2 /day; and/or
the first laminate is made of one selected from a group of polyethylene terephthalate, polyimide, polyethylene; and the second laminate is one selected from a group of a metal foil, a metallized polymer film, and a polymer film with a inorganic oxide coating.

3. The temperature sensor of claim 1 , wherein the control circuitry comprises a constant current driving circuit which drives the NTC thermistor with a constant current, and the NTC thermistor generates a sensed voltage varying with the temperature as follows:
V=I constant *R real-time ;
where V represents the sensed voltage, the I constant represents the constant current supplied by the constant current driving circuit, and the R real-time represents a resistance of the NTC thermistor depending on the temperature.

4. The temperature sensor of claim 3 , wherein the constant current circuit comprises an operation amplifier at least one voltage sources, a first transistor and a second transistor; a first driving voltage and a second driving voltage generated by the at least one voltage sources are respectively applied to two input ends of the operation amplifier to provide a bias for the second transistor at an output end of the operation amplifier; the first transistor and the second transistor are connected into an internal feedback circuit to generate the constant current for the NTC thermistor.

5. The temperature sensor of claim 3 , wherein the control circuitry further comprises a measurement circuit; the measurement circuit comprises at least one amplifier for sampling and amplifying the sensed voltage output through the electrodes of the NTC thermistor.

6. The temperature sensor of claim 5 , furthering comprising a wireless module and a data converter communicated with the control circuitry; the amplified voltage is converted by the data converter to generate a data package, and the data package is transferred to the wireless module for transmitting; wherein the wireless module selects from a group comprising a Bluetooth module, a WiFi module, a Zigbee module or a radio frequency identification (RFID) module.

7. The temperature sensor of claim 1 , wherein the Si—C film has a conformal contact surface for the temperature sensing, and the conformal contact surface has an area of 1-2 cm 2 ;
and/or,
the substrate is a liquid-crystal-polymer (LCP) film with a WVTR of 0.01 gram/m 2 /day.

8. The temperature sensor of claim 1 , wherein the frame element has a front side and a back side which two are configured oppositely to each other; the NTC thermistor is arranged on the front side of the frame element, and the control circuitry and the power source are arranged on the back side of the frame element;
at least a portion of the frame element for arranging the NTC thermistor is made of polytetrafluoroethylene, polyethylene terephthalate, polypropylene, polyvinyl chloride, polyethylene or rubber; and/or a thermal insulation structure is at least disposed on the front side of the frame element corresponding to a portion of the frame element for arranging the NTC thermistor.

9. A wireless temperature sensor, comprising:
an NTC thermistor for temperature sensing, which comprises a substrate, a sensing element, an internal laminate and an external laminate arranged successively; the sensing element comprises a Si—C film and electrodes printed on the substrate, wherein the electrodes connect the Si—C film with a control circuitry;
the internal laminate has a WVTR of 1-100 gram/m 2 /day such that the NTC thermistor is provided with improved thermal curing, and the external laminate has a WVTR of below 0.1 gram/m 2 /day, such that the NTC thermistor is prevented from moisture penetration;
the control circuitry, which electrically connects with the NTC thermistor and operates for obtaining the temperature sensed by the NTC thermistor; the control circuitry comprises a constant current driving circuit for driving the NTC thermistor with a constant current, and a measurement circuit for sampling a sensed voltage output through the electrodes of the NTC thermistor, wherein the sensed voltage is determined based on the constant current and a resistance of the NTC thermistor;
a wireless module for receiving the sensed voltage from the control circuitry and sending out the sensed voltage in a wireless way;
a power source for providing power supply to the NTC thermistor, the control circuitry and the wireless module; and
a frame element for supporting the NTC thermistor, the control circuitry, the power source and the wireless module; wherein the frame element is at least partially thermally insulated to establish thermal equilibrium within the temperature sensor.

10. The temperature sensor of claim 1 , wherein the electrodes are deposited on the substrate to form multiple pairs of fingers, and a gap is provided between each adjacent pairs of the fingers; wherein the Si—C film overlap on each gap between the fingers of the electrodes.

Assignees

• Nano & Advanced Materials Inst Ltd

Inventors

• Sun Caiming
• Chen Xiaohua

Classifications

• H01C17/281

  by thick film techniques · CPC title

• G01K7/226 Primary

  using microstructures, e.g. silicon spreading resistance · CPC title

• A61B2562/164

  the sensor is mounted in or on a conformable substrate or carrier · CPC title

• H01C1/1413

  Terminals or electrodes formed on resistive elements having negative temperature coefficient · CPC title

• G01K7/22

  the element being a non-linear resistance, e.g. thermistor (G01K7/26 takes precedence) · CPC title