Flexible infrared thermopile sensor, sensing array and non-contact temperature measurement method

Abstract

The invention discloses a flexible infrared thermopile sensor, a sensing array and a non-contact temperature measurement method. The sensor comprises a flexible substrate, a patterned tellurium thin film unit, an insulating layer and a reflecting layer which are sequentially arranged from bottom to top, the patterned tellurium thin film unit is attached to the flexible substrate, and through holes are formed in the positions, corresponding to the patterned tellurium thin film unit, of the insulating layer and the reflecting layer; the patterned tellurium thin film unit is partially exposed by the through hole; the patterned tellurium thin film unit comprises a plurality of tellurium thin films which are uniformly distributed in a central symmetry mode, and the tellurium thin films are sequentially connected in series end to end through detection electrodes to form a radial thermopile structure. According to the invention, high-sensitivity and high-precision single-point temperature dynamic detection is realized in a wide temperature zone range, non-contact multi-point simultaneous temperature measurement can be realized by further combining with a wearable technology, and more temperature distribution information is provided.

Description

Technical Field

[0001] The present invention belongs to the technical field of infrared sensing, and particularly relates to a flexible infrared thermopile sensor, a sensing array, and a non-contact temperature measurement method. Background Art

[0002] The skin is the largest organ of the human body. It gives us the sense of touch, and the tactile receptors on its surface can perceive temperature and mechanical stimuli, which is the main window for humans to interact with the environment. Flexible electronic devices that simulate the mechanical properties and tactile perception ability of the skin have currently attracted much attention. Among them, temperature touch can provide temperature information of the environment or the human body, and has broad application prospects and irreplaceable roles in the fields of wearable medical devices, intelligent prosthetics, and new human-computer interaction. At present, the development of the temperature touch function of flexible electronic devices mainly focuses on contact temperature measurement technology, relying on the direct physical contact between the device and the object to be measured. This contact operation mode has obvious disadvantages: flexible electronic devices are easily contaminated and worn. More seriously, there is a risk of physical damage when dealing with harmful temperature stimuli. Therefore, the development of non-contact temperature touch technology helps the long-term damage-free use of devices, avoids the damage risk brought by harmful temperatures, and further broadens and enriches the application scenarios of flexible electronic devices.

[0003] Since the infrared radiation energy emitted by an object is proportional to its surface temperature, non-contact perception of the temperature of a target object can be achieved by detecting infrared radiation. However, applying flexible infrared sensors to the field of non-contact temperature touch still has challenges, mainly reflected in the large-scale integration of flexible electronic devices and the effective detection of low-energy and low-light-intensity infrared radiation emitted by near-room-temperature objects. This poses higher requirements for the material selection and detection performance of flexible infrared sensors.

[0004] As a type of thermosensitive infrared detector, a photothermal-electric detector can convert the absorbed incident radiation into a potential difference output through two energy conversion processes: photothermal conversion and thermoelectric power generation. It has the characteristics of self-power supply, wide spectral response, and working in a room-temperature environment, and is particularly suitable for passive bionic infrared applications. Chinese Patent with the application number 202210626246.4 discloses a non-contact human-computer interaction system based on human infrared radiation detection, in which a thermopile based on perovskite-type composite oxides converts human radiation into an electrical signal. As an infrared radiation sensitive material, perovskite-type composite oxides have a high Seebeck coefficient, and the response voltage of its thermopile is significantly higher than that of commercial thermopiles, realizing sensitive detection of human infrared radiation. However, the perovskite-type composite oxides used in this patent are rigid materials and cannot meet the requirements of miniature flexible integrated infrared sensors. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the present invention provides a flexible infrared thermopile sensor, a sensing array, and a non-contact temperature measurement method. The present invention mainly uses tellurium thin film to convert infrared radiation into electrical signals, so as to realize the application in the field of non-contact temperature touch.

[0006] The technical means adopted by the present invention are as follows:

[0007] An infrared thermopile sensor, comprising: a flexible substrate, a patterned tellurium thin film unit, an insulating layer, and a reflective layer, which are sequentially arranged from bottom to top. The patterned tellurium thin film unit is attached to the flexible substrate, and through holes are provided in the insulating layer and the reflective layer corresponding to the position of the patterned tellurium thin film unit, and the patterned tellurium thin film unit is partially exposed by the through holes;

[0008] The patterned tellurium thin film unit includes a number of tellurium thin films that are evenly distributed in central symmetry. Each tellurium thin film is sequentially connected end to end through a detection electrode to form a radial thermopile structure.

[0009] Further, the tellurium thin film is formed by physical vapor deposition, and the thickness is 100 - 1000 nm.

[0010] Further, the detection electrode includes an adhesion layer and a conductive layer. The material of the adhesion layer includes Ti, Ni, Cr, and the thickness is 5 - 50 nm. The material of the conductive layer includes Au, Pt, and the thickness is 100 - 500 nm.

[0011] Further, the center projection point of the through hole provided in the insulating layer and the reflective layer coincides with the central symmetry point of the patterned tellurium thin film unit. The diameter of the through hole in the reflective layer is larger than the diameter of the through hole in the insulating layer to ensure the insulation between the reflective layer and the thermopile unit below it.

[0012] Further, the material of the insulating layer includes SU-8 photoresist, photosensitive polyimide, silicon oxide, or aluminum oxide, and the thickness is 500 - 2000 nm.

[0013] Further, the material of the reflective layer includes Au, Al, and the thickness is 100 - 500 nm.

[0014] Further, the flexible substrate is a polymer film, including polyimide, polyester, polycarbonate, or polydimethylsiloxane, and the thickness is 10 - 50 μm.

[0015] The present invention also provides a flexible infrared thermopile sensing array, including a number of infrared thermopile sensors as described in any one of the above, and each infrared thermopile sensor is connected by a common electrode.

[0016] Furthermore, the detection electrode and the common electrode are prepared by magnetron sputtering, thermal evaporation, and electron beam evaporation methods.

[0017] The present invention also discloses a non-contact temperature measurement method, which is realized based on the above flexible infrared thermopile sensing array, and includes the following steps:

[0018] Place the object to be measured at a certain distance from the infrared thermopile sensing array, measure the output voltage of any thermopile unit, and reflect the temperature information of the object to be measured according to the sign and value of the output voltage; or

[0019] Place the object to be measured at a certain distance from the infrared thermopile sensing array, and simultaneously measure the output voltages of all thermopile units to obtain a two-dimensional voltage distribution map, thereby obtaining the temperature distribution information of the object to be measured.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. The present invention utilizes the photothermal effect of the tellurium-based thermopile to convert the infrared radiation emitted by objects at different temperatures into electrical signals, and has the advantages of self-power supply and room-temperature operation. It can be used in the field of non-contact temperature touch, which helps the long-term non-destructive use of electronic devices.

[0022] 2. The present invention utilizes the compatibility of tellurium thin film with microfabrication processes to prepare an integrated infrared sensor and sensing array based on tellurium-based thermopiles. Utilizing the flexibility of polymer thin films and tellurium thin films, the provided infrared thermopile sensing array has excellent bendability and conformability, and can be used as a wearable electronic device to closely adhere to the surface of a manipulator or the human body.

[0023] 3. The flexible and wearable infrared thermopile sensing array provided by the present invention has multiple application methods in the field of non-contact temperature touch. Through single-point temperature measurement, high-sensitivity and high-precision real-time temperature detection can be achieved in a wide temperature range. Through multi-point simultaneous temperature measurement, two-dimensional imaging of the temperature distribution can be realized, which can provide novel application scenarios and experiences for intelligent robots, prosthetics, etc. Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0025] Figure 1 It is a schematic structural diagram of a flexible infrared thermopile sensor in an embodiment.

[0026] Figure 2 Schematic diagram of a flexible infrared thermopile sensing array structure in an embodiment.

[0027] Figure 3 Test device diagram of the flexible infrared thermopile sensor in an embodiment for non-contact single-point temperature measurement.

[0028] Figure 4 Dynamic voltage response curves of the flexible infrared thermopile sensor of the present invention and a commercial thermopile in non-contact detection of the temperature of a cold target object in an embodiment.

[0029] Figure 5 Dynamic voltage response curves of the flexible infrared thermopile sensor of the present invention and a commercial thermopile in non-contact detection of the temperature of a hot target object in an embodiment.

[0030] Figure 6 Response voltage change of the flexible infrared thermopile sensor to extremely small temperature changes (~0.05K) in non-contact detection of the temperature of a hot target object in an embodiment.

[0031] Figure 7 Test diagram of the flexible infrared thermopile sensing array of the present invention worn on the back of the hand for non-contact multi-point simultaneous temperature measurement in an embodiment.

[0032] Figure 8 Response voltage distribution diagram of the flexible infrared thermopile sensing array of the present invention worn on the back of the hand to a heat source in the upper left in an embodiment.

[0033] In the figure: 1. Flexible substrate; 2. Discrete tellurium thin film; 3. Detection electrode; 4. Common electrode; 5. Insulating layer; 6. Reflective layer. Detailed implementation manners

[0034] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0035] Embodiment 1

[0036] The present invention provides a flexible infrared thermopile sensor, comprising: a flexible substrate, a patterned tellurium thin film unit, an insulating layer, and a reflective layer, which are sequentially arranged from bottom to top. The patterned tellurium thin film unit is attached to the flexible substrate, and through holes are formed in the insulating layer and the reflective layer at positions corresponding to the patterned tellurium thin film unit, and the patterned tellurium thin film unit is partially exposed through the through holes. Infrared radiation is sensed by the exposed tellurium-based thermopile unit, a temperature difference is established between the exposed part and the unexposed part, and thus an electromotive force difference is generated in the thermopile.

[0037] Specifically, the central projection point of the through hole formed in the insulating layer and the reflective layer coincides with the central symmetry point of the patterned tellurium thin film unit, and the diameter of the through hole in the reflective layer is larger than that of the through hole in the insulating layer to ensure the insulation between the reflective layer and the thermopile unit below it. Preferably, the material of the insulating layer includes SU-8 photoresist, photosensitive polyimide, silicon oxide or aluminum oxide, and the thickness is 500-2000 nm. Further preferably, the material of the reflective layer includes Au, Al, and the thickness is 100-500 nm. Still further preferably, the flexible substrate is a polymer film, including polyimide, polyester, polycarbonate or polydimethylsiloxane, and the thickness is 10-50 μm.

[0038] As a preferred embodiment of the present invention, the patterned tellurium thin film unit includes a plurality of tellurium thin films that are symmetrically and uniformly distributed around a center. Each of the tellurium thin films is sequentially connected in series end to end through a detection electrode to form a radial thermopile structure. Further, the tellurium thin film is formed by physical vapor deposition, and the thickness is 100-1000 nm. Further, the detection electrode includes an adhesion layer and a conductive layer. The material of the adhesion layer includes Ti, Ni, Cr, and the thickness is 5-50 nm. The material of the conductive layer includes Au, Pt, and the thickness is 100-500 nm.

[0039] Example 2

[0040] As Figure 2 shown, this embodiment provides a flexible and wearable infrared thermopile sensing array. The three-dimensional exploded view of one thermopile unit is as Figure 1As shown in the figure. In this embodiment, the flexible substrate 1 is a polyimide film with a thickness of 30 μm. On the polyimide film, 8 discrete tellurium films 2 are prepared by using standard photolithography technology combined with magnetron sputtering coating technology to form a centrally symmetric patterned tellurium film unit. The thickness of the tellurium film is 780 nm, and the Seebeck coefficient is 312 μV / K. Then, the detection electrodes 3 and the common electrodes 4 are prepared by using standard photolithography technology combined with magnetron sputtering coating technology. The detection electrodes electrically connect the 8 discrete tellurium films in series in sequence to form a tellurium-based thermopile unit. The tellurium-based thermopile units are arranged in an array on the polyimide substrate. The common electrodes are connected to each tellurium-based thermopile unit, and the lead ends of the common electrodes and the lead ends of each detection electrode are respectively externally connected to the test unit, so that the voltage generated by each tellurium-based thermopile unit can be obtained. The above electrode material is composed of a 50-nm adhesion layer Ni and a 150-nm conductive layer Pt. An insulating layer 5 and a reflective layer 6 are sequentially arranged above the tellurium-based thermopile array. The insulating layer material is SU-8 photoresist with a thickness of 2000 nm. After standard photolithography technology and thermal curing treatment, the SU-8 insulating layer is provided with through holes arranged in an array. Then, through standard photolithography technology combined with magnetron sputtering coating technology, the topmost Al reflective layer is obtained, with a thickness of 250 nm, and through holes arranged in an array are provided in the middle. The through holes provided in the reflective layer and the insulating layer correspond to the tellurium-based thermopile units one by one. The center projection point of the through hole coincides with the central symmetry point of the patterned tellurium film unit. The diameter of the through hole in the reflective layer is larger than the diameter of the through hole in the insulating layer to ensure the insulation between the reflective layer and the thermopile array below it.

[0041] The tellurium-based thermopile exposed within the range of the circular through hole of the reflective layer senses infrared radiation, and the temperature changes. While the tellurium-based thermopile below the reflective layer is insensitive to the incident radiation, and the temperature remains constant. Thus, a temperature difference is established in the tellurium-based thermopile, and then an electric potential difference is generated. Utilizing the photothermal-electric effect of the tellurium-based thermopile, the infrared radiation emitted by objects at different temperatures can be converted into electrical signals. Combining the flexibility of the polyimide substrate and the tellurium film, the infrared thermopile array can be further used as a wearable electronic device and applied to the field of non-contact temperature touch.

[0042] Example 3

[0043] In this embodiment, the flexible and wearable infrared thermopile sensing array provided in Example 2 is applied to non-contact single-point dynamic temperature measurement. The test device diagram is as Figure 3 shown. The target object to be detected is a metal heating table located in a metal cavity. The flexible thermopile array is fixed at a position 3 mm above the metal heating table, and the dynamic response curve of any one flexible thermopile unit changing with the temperature of the metal heating table is recorded in real time. First, liquid nitrogen is introduced into the metal cavity to cool the metal heating table. Figure 4The dynamic change curve of the response voltage of the flexible thermopile unit was recorded in real time. When the temperature of the metal heating stage gradually decreased from room temperature 295K to 223K, the sign of the response voltage of the flexible thermopile was negative, and the value increased nearly linearly to 2.3 mV. Under the same test conditions, the response voltage value of the SMTIR2102 commercial thermopile of Smartec Company in the Netherlands was always less than that of the flexible thermopile within the test temperature range. When an electric current was passed through the metal heating stage for heating, Figure 5 The dynamic change curve of the response voltage of the flexible thermopile unit was recorded in real time. When the temperature of the metal stage gradually increased from room temperature 295K to 383K, the response voltage of the flexible thermopile increased nearly linearly to about 5.5 mV. Under the same test conditions, the response voltage of the SMTIR2102 commercial thermopile of Smartec Company in the Netherlands was always less than that of the flexible thermopile within the test temperature range. For extremely small temperature changes (~0.05K), the difference in the response voltage of the flexible thermopile could be clearly distinguished, as Figure 6 shown. The above test results show that the flexible infrared thermopile sensing array provided by the present invention can achieve high-sensitivity and high-precision single-point temperature dynamic detection within a wide temperature range.

[0044] Example 4

[0045] In this example, the flexible and wearable infrared thermopile sensing array provided in Example 2 was applied to non-contact multi-point simultaneous temperature measurement. As Figure 7 shown. The thermopile sensing array was externally connected to a flexible printed circuit board and closely adhered to the back of the hand. A thermoelectric cooler (TEC) was placed as a heat source 10 mm above the upper left of the thermopile sensing array, with a temperature of 54 °C. At the same time, the response voltages of 16 thermopiles were recorded, and the two-dimensional voltage distribution map was as Figure 8 shown. It can be seen that the overall response voltage is positive, indicating that the temperature of the target object is higher than that of the thermopile sensing array; the response voltage of the thermopile unit in the upper left corner of the 4×4 array is the largest, and it gradually decreases from the upper left to the lower right, reflecting that the target object is located in the upper left of the thermopile sensing array. This result shows that the flexible and wearable infrared thermopile sensing array provided by the present invention realizes non-contact multi-point simultaneous temperature measurement and provides more temperature distribution information.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flexible infrared thermopile sensor, characterized in that, it includes: A flexible substrate, a patterned tellurium thin film unit, an insulating layer, and a reflective layer are sequentially arranged from bottom to top. The patterned tellurium thin film unit is attached to the flexible substrate, and through holes are provided in the insulating layer and the reflective layer at positions corresponding to the patterned tellurium thin film unit, and the patterned tellurium thin film unit is partially exposed through the through holes; The patterned tellurium thin film unit includes a number of tellurium thin films evenly distributed in central symmetry. Each tellurium thin film is sequentially connected end to end through a detection electrode to form a radial thermopile structure.

2. A flexible infrared thermopile sensor according to claim 1, characterized in that, The tellurium thin film is formed by physical vapor deposition, and the thickness is 100 - 1000 nm.

3. A flexible infrared thermopile sensor according to claim 1, characterized in that, The detection electrode includes an adhesion layer and a conductive layer. The material of the adhesion layer includes Ti, Ni, Cr, and the thickness is 5 - 50 nm. The material of the conductive layer includes Au, Pt, and the thickness is 100 - 500 nm.

4. A flexible infrared thermopile sensor according to claim 1, characterized in that, The center projection point of the through hole provided in the insulating layer and the reflective layer coincides with the central symmetry point of the patterned tellurium thin film unit. The diameter of the through hole in the reflective layer is larger than the diameter of the through hole in the insulating layer to ensure the insulation between the reflective layer and the thermopile unit below it.

5. A flexible infrared thermopile sensor according to claim 1, characterized in that, The material of the insulating layer includes SU-8 photoresist, photosensitive polyimide, silicon oxide or aluminum oxide, and the thickness is 500 - 2000 nm.

6. A flexible infrared thermopile sensor according to claim 1, characterized in that, The material of the reflective layer includes Au, Al, and the thickness is 100 - 500 nm.

7. A flexible infrared thermopile sensor according to claim 1, characterized in that, The flexible substrate is a polymer film, including polyimide, polyester, polycarbonate or polydimethylsiloxane, and the thickness is 10 - 50 μm.

8. A flexible infrared thermopile sensor array, characterized in that, it includes a number of infrared thermopile sensors as described in claim 1 arranged in an array, and each of the infrared thermopile sensors is connected by a common electrode.

9. A flexible infrared thermopile sensor array according to claim 8, characterized in that, The detection electrode and the common electrode are prepared by magnetron sputtering, thermal evaporation, and electron beam evaporation methods.

10. A non-contact temperature measurement method, characterized in that, It is realized based on a flexible infrared thermopile sensor array as described in claim 8, and includes the following steps: Place the object to be measured at a certain distance from the infrared thermopile sensor array, measure the output voltage of any thermopile unit, and reflect the temperature information of the object to be measured according to the sign and value of the output voltage; or Place the object to be measured at a certain distance from the infrared thermopile sensing array, and simultaneously measure the output voltages of all thermopile units to obtain a two-dimensional voltage distribution map, thereby obtaining the temperature distribution information of the object to be measured.

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