Thermopile heat flux sensor device, array, and wearable electronic device

Abstract

The present application relates to a kind of ion polymer-based thermoelectric pile heat flux sensor device, the thermoelectric pile heat flux sensor includes in turn: first protective layer, first connecting circuit, thermal resistance layer, thermoelectric element, second connecting circuit and second protective layer, wherein the thermoelectric element is embedded in the thermal resistance layer and is made of ion conductor with free ion as main carrier. Since ion conductor has huge thermoelectric potential, only a few pairs of ion thermoelectric column need to be integrated to obtain the required thermoelectric voltage with the required sensitivity.

Description

Technical Field

[0001] The present invention relates to a thermopile heat flux sensor device, and more specifically, to a thermopile heat flux sensor device based on ion conductors, as well as an array formed by said device and a wearable electronic device. Background Technology

[0002] Accurate detection of heat flow and trajectory plays a crucial role in numerous fields, including aerospace, MEMS technology, and energy management. The working principle of a thermopile heat flux sensor is as follows: when heat flow passes through the sensor, a temperature difference is generated across the sensor's thermal resistance layer. Based on Fourier's law and the measured temperature difference, the heat flux through the sensor can be calculated using the following formula:

[0003] q=-λΔT / Δx (1)

[0004] Where q is the heat flux, ΔT is the temperature difference between the two ends of the thermal resistance layer, Δx is the thickness of the thermal resistance layer, and λ is the thermal conductivity of the thermal resistance layer.

[0005] The temperature difference can be calculated from the thermoelectric potential generated by the thermopile. To achieve higher accuracy and better small-signal detection capability, a large thermoelectric potential output is required. However, in existing technologies, most reported thermopile heat flux sensors use conventional heavy metal-based inorganic thermocouples with relatively low Seebeck coefficients (typically below 300 μV / k), thus requiring the integration of numerous thermocouples to generate sufficient voltage. The integration of a large number of thermocouples complicates the manufacturing process, and heavy metal-based thermoelectric materials are often toxic and expensive.

[0006] For thermopile heat flux sensors, accurate measurement of the temperature difference (ΔT) is paramount. Existing temperature measurements utilize thermocouples made of Cu, Ni, Pt, or other inorganic thermoelectric materials such as Bi₂Te₃, SbTe, and SbBiTe. These materials offer rapid temperature response and mature fabrication processes. Despite significant advancements, these reported heat flux sensors based on conventional inorganic thermoelectric materials still suffer from several drawbacks. The thermoelectric element of the heat flux sensor should possess low thermal resistance to minimize its impact on the measurement; some designs employ the inorganic thermoelectric material itself as the thermal resistance layer. The inorganic thermoelectric material, as the thermoelectric element, requires low thermal resistance, which, when used as a thermal resistance layer, results in a small temperature difference, leading to a weak output signal. Furthermore, conventional thermoelectric materials offer relatively low thermopower, typically below 300 μV / K, resulting in excessive integration requirements and complicating the manufacturing process. Existing thermopile heat flux sensors typically require at least 50 thermoelectric material pairs connected in series to achieve an acceptable voltage. In addition, the high price of thermoelectric raw materials such as Bi2Te3 makes it difficult to control costs.

[0007] Therefore, there is an urgent need in this field to develop thermoelectric materials with high thermoelectric potential, low cost, and preferably high thermal resistance for thermopile heat flux sensor applications. Summary of the Invention

[0008] As mentioned above, there is an urgent need in the field to develop thermoelectric materials with high thermoelectric potential, low cost, and preferably high thermal resistance for thermopile heat flux sensor applications.

[0009] Therefore, in a first aspect, the present invention provides a thermopile heat flux sensor device, the thermopile heat flux sensor comprising, in sequence: a first protective layer, a first connecting circuit, a thermal resistance layer, a thermoelectric element, a second connecting circuit, and a second protective layer, wherein the thermoelectric element is embedded in the thermal resistance layer and is made of an ion conductor with free ions as the main charge carriers.

[0010] In one embodiment, the ion conductor is polymer-based. In a preferred embodiment, the ion conductor is an ion-conducting polymer, an ion-conducting polymer gel, a solid polymer-based electrolyte, and / or an ion-conducting polymer composite.

[0011] In one embodiment, the ionic conductor has a Seebeck coefficient >1 mV / K and / or a thermal conductivity <1 W / m·K.

[0012] In one embodiment, the thermoelectric element comprises one or more pairs of ion thermoelectric columns, wherein one ion thermoelectric column is made of an N-type ion conductor and the other ion thermoelectric column is made of a P-type ion conductor, and in the case where the thermoelectric element comprises multiple pairs of ion thermoelectric columns, the multiple pairs of ion thermoelectric columns are connected in series via the first connection circuit and the second connection circuit.

[0013] In one embodiment, the N-type ion conductor is a LiBF4 / EMIMTFSI / PVDF-HFP ion gel or a NaTFSI / TPFPB / PC / PVDF-HFP ion gel, and the P-type ion conductor is an EMIMCl / EMIMTFSI / PVDF-HFP ion gel or a NaTFSI / PC / PVDF-HFP ion gel.

[0014] In a further embodiment, the N-type ion conductor is a LiBF4 / EMIMTFSI / PVDF-HFP ion gel, and the concentration of LiBF4 is 0.2-0.5M; the P-type ion conductor is an EMIMCl / EMIMTFSI / PVDF-HFP ion gel, and the concentration of EMIMCl is 0.4-1.0M, preferably 0.5M.

[0015] In one embodiment, the thermal resistance layer has a thermal conductivity of less than 5 W / m·K.

[0016] In one embodiment, the thermal resistance layer is made of a flexible polymer or an inorganic material. As an example, the flexible polymer may be epoxy resin, polyimide, or polyethylene, and the inorganic material may be rock wool board.

[0017] In one embodiment, both the first and second connection circuits are made of a conductive material. As an example, the conductive material can be a metal, semiconductor, conductive polymer, or conductive ceramic.

[0018] In one embodiment, the first connection circuit and the second connection circuit are in the form of an array of multiple electrodes.

[0019] In one embodiment, the thermopile heat flux sensor device is a flexible sensor device, wherein the first protective layer, the second protective layer, and the thermal resistance layer are all made of flexible materials.

[0020] In a second aspect, the present invention provides a thermopile heat flux sensor array, comprising two or more thermopile heat flux sensor devices of the first aspect of the present invention as sensor units.

[0021] In one embodiment, the thermopile heat flux sensor devices may have the same or different structures from each other.

[0022] In one implementation, the thermopile heat flux sensor devices are not connected in series with each other.

[0023] In a third aspect, the present invention provides a wearable electronic device comprising a thermopile heat flux sensor device of the first aspect of the present invention or a thermopile heat flux sensor array of the second aspect of the present invention.

[0024] The present invention has one or more of the following beneficial technical effects:

[0025] The ion thermopile heat flux sensor of this invention uses P-type and N-type ion thermocouples with giant ion thermoelectric potentials. Therefore, only a few thermocouples need to be integrated to obtain the required thermal voltage. Compared with heat flux sensors based on inorganic thermoelectric materials, it has the advantages of low cost and easier integration.

[0026] The thermoelectric element in the ion thermopile heat flux sensor of this invention is based on ion thermoelectric polymer rather than on conductor or semiconductor thermoelectric materials, thus having very good flexibility. It can adapt well to curved surfaces under some special testing requirements, making it more suitable for the needs of wearable devices.

[0027] This invention uses an ion conductor that generates thermal voltage through the non-uniform distribution of ions under temperature difference. The ion conductor not only has a huge thermoelectric potential and low thermal conductivity, but also has a low price. This means that the ion thermopile heat flux sensor of this invention can have higher sensitivity and is more suitable for mass production. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other implementation schemes can be obtained based on these drawings without creative effort.

[0029] Figure 1 The diagram illustrates the working principle of a polymer-based thermopile heat flux sensor device (A), where the heat flux is calculated according to q = -λdT / dx, and dT is equal to the voltage divided by the thermoelectric potential; and a photograph (B) shows an embodiment of the sensor of the present invention.

[0030] Figure 2 A cross-sectional view of a specific embodiment of the thermopile heat flux sensor device of the present invention is shown.

[0031] Figure 3The thermoelectric voltage of P-type (A) and N-type (B) ionic conductors as a function of temperature difference is shown.

[0032] Figure 4 A graph showing the relationship between thermoelectric potential and salt type is presented.

[0033] Figure 5 The thermoelectric potentials change with varying concentrations of salts LiBF4 (left) and EMIMCl (right).

[0034] Figure 6 The diagram shows the voltage generated when the thermopile heat flux sensor device of the present invention is worn on a human arm at 25°C (A), the voltage variation with temperature difference (B), the linear fit of voltage and temperature difference (C), and the relationship between the thermal conductivity of ionic polymers containing different proportions of electrolyte and PVDF-HFP. Detailed Implementation

[0035] The present invention will now be clearly and completely described in conjunction with its embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments that can be obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0036] In the description of this invention, the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0037] Furthermore, the terms "first," "second," and other ordinal numbers are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature modified by the terms "first" or "second" may explicitly or implicitly include at least one of those features. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0038] In this invention, unless otherwise explicitly specified and limited, terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0039] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that they are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0040] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0041] As mentioned above, there is an urgent need in the field to develop thermoelectric materials with high thermoelectric potential, low cost, and preferably high thermal resistance for thermopile heat flux sensor applications.

[0042] Therefore, in a first aspect of the present invention, a thermopile heat flux sensor device is provided, the thermopile heat flux sensor comprising, in sequence: a first protective layer, a first connecting circuit, a thermal resistance layer, a thermoelectric element, a second connecting circuit, and a second protective layer, wherein the thermoelectric element is embedded in the thermal resistance layer and is made of an ion conductor with free ions as the main charge carriers.

[0043] These components will be described one by one below.

[0044] The thermopile heat flux sensor device includes a first protective layer and a second protective layer, which are located on the outermost side of the device.

[0045] As the name suggests, the term "protective layer" refers to a protective layer that encloses the relatively fragile first connection circuit, thermal resistance layer, thermoelectric element, and second connection circuit. The first and second protective layers can exist as two separate components, their edges directly bonded (e.g., glued) together, or bonded together by a side protective layer. Alternatively, the first and second protective layers can also exist as a single component, enclosing the first connection circuit, thermal resistance layer, thermoelectric element, and second connection circuit by folding; in this case, similarly, the other edge portions besides the folded edge are also directly bonded (e.g., glued) together, or bonded together by an additional protective layer.

[0046] The first and second protective layers, as well as any possible side protective layers, can be made of any rigid or flexible material. As examples, the materials may include rigid materials such as silicon, and flexible materials such as polyimide and polyethylene, but are not limited thereto. When the thermopile heat flux sensor device of the present invention is intended to be manufactured as a flexible sensor device, preferably, the first and second protective layers, as well as the optional side protective layers, are all made of flexible materials such as polyimide or polyethylene.

[0047] The thermopile heat flux sensor device also includes a first connection circuit and a second connection circuit.

[0048] Both the first and second connection circuits are made of conductive materials. For example, the conductive material can be a metal such as gold, silver, copper, aluminum, or alloys thereof; a semiconductor such as doped silicon or silicon-germanium alloys; a conductive polymer such as polyaniline, polypyrrole, polythiophene, and poly(p-styrene) and their derivatives; or a conductive ceramic.

[0049] In addition, in this invention, the first connection circuit and the second connection circuit can be in the form of an array of multiple electrodes, and are in direct and staggered contact with the thermoelectric element embedded in the thermal resistance layer, thereby realizing the series connection of the thermoelectric element (in the case of multiple ion thermoelectric columns).

[0050] The thermopile heat flux sensor device also includes a thermal resistance layer located at the very center.

[0051] A "thermal resistance layer" refers to a material layer made of a material with low thermal conductivity. Thermal conductivity can also be called "thermal conductivity coefficient" or "thermal conductivity level". The purpose of using a thermal resistance layer is to reduce or even prevent heat transfer, thereby improving the detection of temperature changes. Preferably, the thermal resistance layer has a thermal conductivity of less than 5 W / m·K. The thermal resistance layer can be made of organic or inorganic materials. As an example, the organic material can be a flexible polymer, such as epoxy resin (0.2 W / m·K), polyimide (0.2 W / m·K), or polyethylene (0.3 W / m·K), and the inorganic material can be rock wool board.

[0052] The thermopile heat flux sensor device also includes a thermoelectric element embedded in the thermal resistance layer.

[0053] Traditional thermoelectric elements are mostly made of electrical conductors or semiconductor materials. For electrical conductors, such as metals, their conductivity is caused by the movement of electrons, while for semiconductors, their conductivity is related to the movement of electrons or holes. In this invention, the thermoelectric element is made of an ionic conductor, which acts as an ionic capacitor and generates a thermoelectric response through the non-uniform distribution of ions in the presence of a temperature difference.

[0054] An "ionic conductor" is a conductor in which electric current is generated by mobile ion charges. Unlike electrical conductors or semiconductors, the charge carriers in an ionic conductor are neither electrons nor holes, but mobile ions. Ions can be classified as positively charged cations or negatively charged anions, and correspondingly, there are cation conductors and anion conductors.

[0055] In theory, any ionic conductor can be used to manufacture the thermopile heat flux sensor device of this invention. However, in practice, it is preferred to use an ionic conductor that simultaneously possesses a high Seebeck coefficient (>1 mV / K) and a low thermal conductivity (<1 W / m·K). For example, among the two ionic conductors specifically used in the embodiments of this invention, the Seebeck coefficient and thermal conductivity of 0.5 M EMIMCl / EMIMTFSI / PVDF-HFP (P-type thermoelectric material) are +17 mV / K and 0.1889 W / m·K, respectively, and the Seebeck coefficient and thermal conductivity of 0.5 M LiBF4 / EMIMTFSI / PVDF-HFP (N-type thermoelectric material) are -15 mV / K and 0.2049 W / m·K, respectively.

[0056] The ion conductor of the present invention can be a polymer-based ion conductor. Preferably, the ion conductor is an ion-conducting polymer, an ion-conducting polymer gel, a solid polymer-based electrolyte, or an ion-conducting polymer composite.

[0057] As an example, the ion-conducting polymer may be polyaniline, polypyrrole and its derivatives, fluoropolymers, such as solid electrolytes based on polyvinylidene fluoride (PVDF), but is not limited thereto.

[0058] As an example, the ionomer gel may be a gel formed from polyaniline, polypyrrole and its derivatives, fluoropolymers and electrolyte, such as PVDF-based ionomer gels or hydrogels, but is not limited thereto.

[0059] As an example, the solid polymer-based electrolyte may be polyethylene oxide (PEO), polyvinyl alcohol (PVA), or other solid electrolytes based on PEO or PVA, but is not limited thereto.

[0060] As an example, the polymer composite ion conductor, also known as an "ion-conducting polymer composite", can be a composite of the aforementioned ion-conducting polymer, ion polymer gel, or solid polymer-based electrolyte with inorganic fillers, such as a solid electrolyte or electrolyte gel containing inorganic fillers such as silica (SiO2) particles, but is not limited thereto.

[0061] In this invention, the salts that can be used may include alkali metal salts and halide salts. As examples, the alkali metal salts may include organic or inorganic salts containing lithium (Li) ions, sodium (Na) ions, potassium (K) ions, rubidium (Rb) ions, etc.; as examples, the halide salts may include organic or inorganic salts containing fluoride (F) ions, chloride (Cl) ions, bromide (Br) ions, iodide (I) ions, astatine (At) ions, etc. By changing the type of salt, the Seebeck coefficient of the ionic conductor can be adjusted. Preferably, for P-type ionic conductors, the salt is a halide salt, particularly a salt containing chloride (Cl) ions, such as EMIMCl; for N-type ionic conductors, the salt is an alkali metal salt, particularly a salt containing lithium (Li) ions, such as LiBF4.

[0062] In this invention, the thermoelectric element can consist of one or more pairs of ion thermoelectric columns. In a pair of ion thermoelectric columns, one ion thermoelectric column is made of an N-type ion conductor, and the other ion thermoelectric column is made of a P-type ion conductor. Furthermore, in this invention, the ion thermoelectric columns can be in the form of a thin film or a bulk material.

[0063] The term "N-type ionic conductor" refers to an ionic conductor with a negative equivalent Seebeck coefficient. As examples, N-type ionic conductors may include, for instance, LiBF4 / EMIMTFSI / PVDF-HFP ionogels and NaTFSI / TPFPB / PC / PVDF-HFP ionogels, but are not limited to these. Any other existing N-type ionic conductors may be used in this invention.

[0064] The term "P-type ionic conductor" refers to an ionic conductor with a positive equivalent Seebeck coefficient. As examples, P-type ionic conductors may include, for instance, EMIMCl / EMIMTFSI / PVDF-HFP ionic gels and NaTFSI / PC / PVDF-HFP ionic gels, but are not limited to these. Any other existing P-type ionic conductors may be used in this invention.

[0065] As can be seen from the examples above, changing the type of salt in the ionic conductor can allow the ionic conductor to switch between P-type and N-type. Furthermore, the salt concentration is related to the optimal thermoelectric potential. In this invention, the inventors have found that for LiBF4 / EMIMTFSI / PVDF-HFP ionic gels, the concentration of LiBF4 is 0.2-0.5 M, and for EMIMCl / EMIMTFSI / PVDF-HFP ionic gels, the concentration of EMIMCl is 0.4-1.0 M, preferably 0.5 M.

[0066] When the thermoelectric element is composed of multiple pairs of ion thermoelectric columns, the multiple pairs of ion thermoelectric columns are connected in series via the first connection circuit and the second connection circuit, thereby enabling the detection of temperature changes by voltage changes.

[0067] Existing thermopile heat flux sensors employ conductive or semiconductor materials, which have very low Seebeck coefficients, typically below 300 μV / K. Therefore, thermopile heat flux sensors based on conductive or semiconductor materials usually require the integration of a large number of thermopile pairs, such as at least 50, to achieve acceptable voltage. The integration of a large number of thermopile pairs leads to complex manufacturing processes, and thermoelectric materials based on heavy metals are often toxic and expensive.

[0068] In contrast, ionic conductors possess enormous thermoelectric potentials, with Seebeck coefficients all exceeding 1 mV / K. For example, the Seebeck coefficients of the 0.5 M EMIMCl / EMIMTFSI / PVDF-HFP (P-type thermoelectric material) and the 0.5 M LiBF4 / EMIMTFSI / PVDF-HFP (N-type thermoelectric material) specifically used in this invention are +17 mV / K and -15 mV / K, respectively. Therefore, when applying ionic conductors to thermopile heat flux sensor devices, high thermoelectric potentials can be obtained without integrating too many ionic thermoelectric column pairs, thereby achieving sensitive detection.

[0069] The multiple pairs of ion thermoelectric pillars can be embedded in the thermal resistance layer, for example, in the form of an array, such that the array can be of the form n×m, where n and m are each independently an integer greater than or equal to (≥) 1. For example, n and m can each be any number of 1, 2, 3, 4, 5, or 6. As an example, Figure 1A sensor device comprising 24 (12 pairs) ion thermoelectric columns is shown, wherein these 24 ion thermoelectric columns are embedded in the thermal resistance layer in a 4×6 array. Despite integrating only 12 pairs of ion thermoelectric columns in total, a total thermoelectric potential of 0.3579 V / K is achieved. This represents a 700-fold increase in sensitivity compared to commercial thermopile heat flux sensors that typically use copper-constantan thermocouples to provide a paired thermoelectric potential of 42 μV / K.

[0070] Figure 2 A cross-sectional view of the thermopile heat flux sensor device of the present invention is shown. As can be seen from the figure, the thermopile heat flux sensor device of the present invention, from bottom to top, consists of a first protective layer 1, an electrode 2 (as a first connecting circuit), a thermal resistance layer 4, an N-type thermoelectric column 3', a P-type thermoelectric column 3"", an electrode 5 (as a second connecting circuit), and a second protective layer 6. A side protective layer 7 is also shown in the figure. An N-type thermoelectric column 3' and a P-type thermoelectric column 3" constitute a pair of ion thermoelectric columns, which are in direct and staggered contact with the electrodes 2 and 5 located above and below them, respectively. Through these upper and lower electrodes, or the first and second connecting circuits, multiple pairs of ion thermoelectric columns can be connected in series, thereby enabling the output of a larger signal.

[0071] Furthermore, it should be noted that in this invention, since the ionic conductor is based on a polymer, a solution method can be used to inject the ionic conductor into the pre-formed cavity in the thermal resistance layer during the fabrication of the thermopile heat flux sensor device of this invention. Therefore, the manufacturing method is simple, easy to implement, and cost-effective. In addition, compared to traditional conductors or semiconductor materials, the cost of ionic conductors is much lower, thus also making it cost-effective from a raw material perspective.

[0072] In a second aspect, the present invention provides a thermopile heat flux sensor array, including the thermopile heat flux sensor device of the first aspect of the present invention as a sensor unit.

[0073] The thermopile heat flux sensor devices may have the same or different structures, depending on the specific requirements.

[0074] These thermopile heat flux sensor devices are preferably not connected in series with each other, so that different parts can be detected simultaneously.

[0075] In a third aspect, a wearable electronic device is provided, the wearable electronic device comprising a thermopile heat flux sensor device of the first aspect of the present invention or a thermopile heat flux sensor array of the second aspect of the present invention.

[0076] As described above, the thermoelectric element of the thermopile heat flux sensor device of the present invention can be manufactured using an ion conductor, thus allowing the thermoelectric element to be flexible. In this case, if other components of the thermopile heat flux sensor device are also manufactured using flexible materials, then the detection of heat flux on some curved surfaces can be achieved.

[0077] The sensor of this invention has a wide range of applications, such as in the field of thermal radiation, including thermal imaging, night vision, non-destructive defect analysis, biomonitoring, and wearable devices. Because the sensor is combined with a flexible polymer, the device can be attached to curved surfaces (such as the human body) to detect heat flow, which greatly expands its application scenarios.

[0078] Example

[0079] The invention will be described below with reference to several embodiments and the accompanying drawings. It should be understood that these embodiments are merely examples and are not intended to limit the scope of the invention.

[0080] Abbreviations and their full names:

[0081]

[0082] Example 1

[0083] First, a salt (LiBF4 or EMIMCl) is dissolved in the ionic liquid EMIMTFSI at the desired molar concentration (0.2-1M) to prepare an electrolyte solution. Simultaneously, PVDF-HFP is dissolved in acetone, and this polymer solution is stirred at 50°C until PVDF-HFP is completely dissolved in the acetone and the solution becomes transparent and homogeneous. The premixed electrolyte solution is then added to the PVDF-HFP solution, and the mixture is stirred for half an hour. Finally, the resulting solution is dropped onto a glass slide and dried in a 60°C oven for 10 minutes to form a separate polymer gel film.

[0084] Thermoelectric potential measurements were then performed. These measurements were conducted on a homemade apparatus, measuring in-plane directions. Two Peltier devices were used to create the hot and cold terminals. Two T-type thermocouples were placed on copper electrodes close to the polymer gel. The thermocouple tips were coated with thermal grease to ensure accurate temperature difference measurements. A Keithley 2182A voltmeter and a National Instruments 9213 thermocouple data logger were connected to a computer, recording the thermoelectric voltage and temperature every 2 seconds. Temperature and voltage typically stabilized within 2 minutes. Measurements were performed at room temperature (~25°C) and ~60% RH, unless otherwise specified.

[0085] Next, the thermal conductivity was measured using the hot plate method. Specifically, the hot wire was made into a disc shape, sandwiched between two samples, and electricity was applied to heat the probe. The change in probe resistance with temperature was recorded, and the thermal conductivity was calculated.

[0086] Figure 3 The thermoelectric voltages of P-type (A) and N-type (B) ionic conductors as a function of temperature difference are shown. The thermoelectric potentials can be obtained by linearly fitting these data, where the coefficient of determination r0 is... 2 The values ​​are 0.9957 (for P-type polymers) and 0.99967 (for N-type polymers), respectively, which indicates that the ionic conductor used in this invention has an extremely good linearity between the thermoelectric potential it generates and the temperature difference.

[0087] in addition, Figure 4 A graph showing the relationship between thermoelectric potential and salt type is presented. The graph shows that in the absence of salt, the thermoelectric potential is only -4 mV / K (EMIMTFSI / PVDF-HFP), while with the addition of 0.5 M LiBF4, the thermoelectric potential reaches as high as -15 mV / K (LiBF4 / EMIMTFSI / PVDF-HFP), and with the addition of EMIMCl, the thermoelectric potential can reach as high as +17 mV / K (EMIMCl / EMIMTFSI / PVDF-HFP). These results demonstrate that ionic thermoelectric materials possess a significantly larger thermoelectric potential, thus eliminating the need for integrating numerous ionic thermoelectric pairs in practical applications. Furthermore, the interconversion between P-type and N-type ionic conductors can be easily achieved simply by considering the salt type.

[0088] In addition to the influence of salt type on thermoelectric potential, salt concentration also has a significant impact on thermoelectric potential. Figure 5 The figure shows the thermoelectric potential as the concentrations of LiBF4 (left) and EMIMCl (right) salts change. It can be seen from the figure that the thermoelectric potential is relatively higher when the LiBF4 concentration is 0.2–0.5 M, while it is relatively higher when the EMIMCl concentration is 0.4–1.0 M, reaching a peak at a concentration of 0.5 M.

[0089] Example 2

[0090] In this embodiment, a thermopile heat flux sensor device is manufactured using the following method, which includes the following steps:

[0091] 1. Pre-perforate a total of 24 holes in a 1 mm thick 3M VHB tape to serve as cavities for containing ionomer materials.

[0092] 2. Take two layers of polyethylene film, and deposit multiple copper electrodes in a predetermined pattern on one side of each polyethylene film to serve as connection circuits. Note that at least a portion of the patterned copper electrodes should correspond in position to the holes on the 3M VHB tape.

[0093] 3. Place pre-perforated 3M VHB tape on the side of a polyethylene film on which copper electrodes are deposited, such that every two holes on the tape are above one copper electrode.

[0094] 4. P-type and N-type ionomer materials are alternately injected into the holes on the 3M VHB tape. Since the 3M VHB tape has 24 holes, a total of 12 ion thermocouples are formed.

[0095] 5. Place another polyethylene film on 3M VHB tape, with the side containing the copper electrodes facing the tape. The copper electrodes on this polyethylene film do not simultaneously contact the same pair of ion thermocouples as the copper electrodes from step 2; instead, they contact the ion thermocouples located between them in an alternating manner. In this way, the 12 ion thermocouples are connected in series via the upper and lower copper electrodes.

[0096] Figure 1 A schematic diagram (A) illustrating the working principle of a polymer-based heat flux sensor and a prototype thermopile heat flux sensor device (B) are shown. Figure 2 A schematic cross-sectional view of the heat flux sensor device is shown.

[0097] Example 3

[0098] This embodiment tested the performance of the prototype thermopile heat flux sensor device manufactured in Embodiment 2, including thermoelectric potential, thermal conductivity, and heat flux detection capability.

[0099] First, the inventors tested the thermoelectric potential and thermal conductivity of the thermopile heat flux sensor device in Example 2. The specific testing method is as follows: A T-type thermocouple was installed on the inside of a polyethylene film. During the test, the T-type thermocouple was sandwiched between two Peltier modules that generated a temperature difference to obtain the thermoelectric potential. The thermal conductivity was estimated.

[0100] Secondly, the inventors also tested the heat flux detection capability of the thermopile heat flux sensor device. Specifically, the prototype thermopile heat flux sensor device from Example 2 was worn on the arm, and the heat flux detection capability of the thermopile heat flux sensor of the present invention was tested by detecting the heat flux on the surface of the arm.

[0101] Figure 6 The performance test results of the prototype thermopile heat flux sensor device of the present invention are shown, wherein:

[0102] Figure 6 Figure A illustrates the heat flux detection capability of the thermopile heat flux sensor of the present invention. As can be seen from the figure, when the thermopile heat flux sensor device is worn on the arm, because one side is immediately heated by the warm skin, a sharp voltage increase to 0.33V is observed within 10 seconds. The voltage then decays as the temperature propagates from the skin to the upper surface of the device, i.e., the surface not in contact with the arm, until it reaches a plateau voltage of approximately 0.07V. A small wind disturbance at 200 seconds is also recorded through voltage changes. These results demonstrate that the thermopile heat flux sensor device of the present invention is highly sensitive.

[0103] Figure 6 Figure B shows the relationship between the temperature difference and the voltage generated by the thermopile heat flux sensor. As can be seen from the figure, there is a high correlation between the temperature difference and the voltage.

[0104] Figure 6 Figure C shows the fitted curve of the overall thermoelectric potential for the thermopile heat flux sensor of the present invention. As can be seen from this figure, the thermopile heat flux sensor of the present invention has a total thermoelectric potential as high as 0.3579 V / K.

[0105] Based on the measured total thermoelectric potential, the temperature difference across the device is approximately 0.2 K. Using the thermal conductivity of the polymer (0.18 W / (m·K) and 0.19 W / (m·K)), the transplane heat flux is calculated to be 34.8 W·m. -2 / (m·K)). The measured temperature difference between the air and the skin is approximately 8K, therefore, the corresponding convective heat transfer coefficient can be calculated as 4.35 W·m based on the measured heat flux. -2 K -1 This coefficient indicates that the heat transfer is within a suitable range for natural convection.

[0106] Figure 6 D illustrates the relationship between the thermal conductivity of the thermopile heat flux sensor of the present invention and the weight ratio between the electrolyte and PVDF-HFP. The results show that for each ionic thermoelectric polymer doped with 0.5M salt in the ionic liquid, although the weight ratio between the electrolyte and PVDF-HFP is different, the thermoelectric potential of these ionic thermoelectric polymers is almost equivalent, indicating that their thermoelectric potential is essentially independent of the weight ratio between the electrolyte and PVDF-HFP.

[0107] Therefore, this device can be used as a wearable heat flux sensor in the healthcare field for, for example, highly sensitive monitoring of human body heat flux.

Claims

1. A thermopile heat flux sensor device comprising, in order: The first protective layer, the first connecting circuit, the thermal resistance layer, the thermoelectric element, the second connecting circuit, and the second protective layer are characterized in that the thermoelectric element is embedded in the thermal resistance layer and is made of an ionic conductor with free ions as the main charge carriers; The thermoelectric element is composed of one or more pairs of ionic thermoelectric columns, in one pair of ionic thermoelectric columns, one ionic thermoelectric column is made of an N-type ionic conductor, and the other ionic thermoelectric column is made of a P-type ionic conductor, and in the case of the thermoelectric element being composed of multiple pairs of ionic thermoelectric columns, the multiple pairs of ionic thermoelectric columns are connected in series via the first connecting circuit and the second connecting circuit.

2. The thermopile heat flux sensor apparatus of claim 1, wherein, The ionic conductor is polymer-based; preferably, the ionic conductor is an ion-conducting polymer, an ion-conducting polymer gel, a solid-state polymer-based electrolyte, and / or an ion-conducting polymer composite.

3. The thermopile heat flux sensor apparatus of claim 1, wherein, The ionic conductor has a Seebeck coefficient of >1 mV / K and / or a thermal conductivity of <1 W / m·K.

4. The thermopile heat flux sensor apparatus of claim 1, wherein, The N-type ionic conductor is LiBF4 / EMIMTFSI / PVDF-HFP ionic gel or NaTFSI / TPFPB / PC / PVDF-HFP ionic gel, and the P-type ionic conductor is EMIMCl / EMIMTFSI / PVDF-HFP ionic gel or NaTFSI / PC / PVDF-HFP ionic gel.

5. The thermopile heat flux sensor device of any one of claims 1-4, wherein, The N-type ionic conductor is LiBF4 / EMIMTFSI / PVDF-HFP ionic gel, and the concentration of LiBF4 is 0.2-0.5 M, and the P-type ionic conductor is EMIMCl / EMIMTFSI / PVDF-HFP ionic gel, and the concentration of EMIMCl is 0.4-1.0 M.

6. The thermopile heat flux sensor apparatus of claim 5, wherein, The concentration of EMIMCl is 0.5 M.

7. The thermopile heat flux sensor device of any one of claims 1-4, wherein, The thermal resistance layer has a thermal conductivity of less than 5 W / m·K.

8. The thermopile heat flux sensor apparatus of claim 7, wherein, The thermal resistance layer is made of a flexible polymer or an inorganic material.

9. The thermopile heat flux sensor apparatus of claim 8, wherein, The flexible polymer is epoxy resin, polyimide, or polyethylene.

10. The thermopile heat flux sensor apparatus of claim 8, wherein, The inorganic material is rock wool board.

11. The thermopile heat flux sensor device of any one of claims 1-4, wherein, The first connecting circuit and the second connecting circuit are both made of conductive material.

12. The thermopile heat flux sensor apparatus of claim 11, wherein, The conductive material is metal, semiconductor, conductive polymer, or conductive ceramic.

13. The thermopile heat flux sensor apparatus of any one of claims 1-4, wherein, The first connecting circuit and the second connecting circuit are in the form of an array composed of multiple electrodes.

14. The thermopile heat flux sensor apparatus of any one of claims 1-4, wherein, The thermoelectric pile heat flux sensor device is a flexible sensor device, wherein the first protective layer and the second protective layer and the thermal resistance layer are all made of flexible material.

15. A thermoelectric pile heat flux sensor array comprising 2 or more thermoelectric pile heat flux sensor devices according to any one of claims 1-14 as sensor units.

16. The thermopile heat flux sensor array of claim 15, wherein, The thermoelectric pile heat flux sensor devices have the same or different structures from each other.

17. The thermopile heat flux sensor array of claim 15 or 16, wherein, The thermoelectric pile heat flux sensor devices are not connected in series with each other.

18. A wearable electronic device, comprising: The wearable electronic device contains the thermoelectric pile heat flux sensor device according to any one of claims 1-14 or the thermoelectric pile heat flux sensor array according to any one of claims 15-17.

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