Flexible baseband differential atomic layer thermopile heat flow sensor and preparation method thereof
By arranging sensing structures with opposite tilt angles side by side on a flexible substrate, a flexible ALTP sensor is fabricated, which solves the problems of bonding with irregular curved surfaces and the Seebeck effect of traditional sensors, achieves high-precision heat flow measurement, simplifies the fabrication process, and reduces costs.
Patent Information
- Application Number
- CN202511690293.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-18
- Publication Date
- 2026-03-27
AI Technical Summary
Existing ALTP sensors are difficult to fit tightly on irregular curved surfaces, introducing heat flow measurement errors. Furthermore, the parasitic Seebeck effect severely affects measurement accuracy, and existing compensation methods are complex and have limited accuracy.
A heat flux sensor using a flexible Hastelloy substrate and a differential structure atomic layer thermopile is developed. By arranging sensing structures with opposite tilt angles side by side on the flexible substrate, MgO and LCMO thin films are prepared using electron beam evaporation and chemical vapor deposition processes to achieve electrical connection, thereby canceling parasitic signals and enhancing voltage gain.
It effectively suppresses the traditional Seebeck effect, improves measurement accuracy and sensitivity, simplifies the preparation process, reduces costs, and expands the application range to heat flow measurement in complex temperature fields.
Smart Images
Figure CN121751962A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of heat flow sensors, and particularly relates to an atomic layer thermopile heat flow sensor based on a flexible baseband and a differential structure to realize error compensation. BACKGROUND
[0002] Atomic layer thermopile (ALTP) heat flow sensors have been widely used in the measurement of element surface heat flow in recent years. The sensors are based on the transverse thermoelectric effect and can convert the longitudinal temperature gradient between the upper and lower surfaces of the sensitive film into a transverse thermoelectric voltage, thereby realizing direct measurement of heat flow. However, the ALTP sensor usually adopts a buried installation method, and the crystal substrate has problems such as great brittleness and millimeter-level thickness, which makes it difficult to closely adhere to the irregular curved surface, thereby introducing significant heat flow measurement errors. A flexible Hastelloy baseband solves this problem, which uses high-flexibility Hastelloy as the baseband material, maintains the original thermoelectric conversion performance of the ALTP, and significantly improves the mechanical flexibility and adhesion ability of the device. It can adapt to different shapes of curved surfaces and realize reliable installation, thereby fundamentally solving the measurement error problem caused by poor adhesion of traditional rigid sensors to irregular surfaces.
[0003] An ideal ALTP sensor should only be sensitive to the heat flow in the normal direction of its surface. However, the ALTP sensor prepared by the prior art has a non-uniform temperature distribution (i.e., a transverse temperature gradient Delta T X ) in the sensitive surface, which will excite the intrinsic conventional Seebeck effect ( U SE ), generating a parasitic signal unrelated to the normal heat flow. This parasitic interference seriously restricts the measurement accuracy and becomes a key technical bottleneck hindering its practical application in high-precision scenarios.
[0004] To suppress the parasitic Seebeck effect, the prior art usually adopts the method of introducing an auxiliary temperature sensor to monitor the transverse thermal gradient in real time and implement signal compensation. However, this method has obvious limitations: on the one hand, it relies on external temperature sensors for compensation, significantly increasing the complexity and integration difficulty of the system; on the other hand, the compensation accuracy is largely limited by the calibration accuracy of the temperature sensor itself, and in actual application, the compensation effect may be reduced due to calibration deviation or sensor drift, affecting the reliability of the overall measurement. SUMMARY
[0005] The technical problem to be solved by the present application is to provide a flexible baseband differential atomic layer thermopile heat flow sensor that can eliminate the parasitic signal interference of the conventional Seebeck effect ( U SE ), and a preparation method thereof.
[0006] The technical scheme adopted by the present application to solve the technical problem is a flexible baseband differential atomic layer thermoelectric pile heat flow sensor, characterized in that it comprises a first sensing structure and a second sensing structure arranged side by side along the y-axis direction on a flexible baseband, the first sensing structure comprises a first directional growth layer, a first interface modification layer and a first heat flow sensitive functional layer arranged sequentially and upwardly along the z-axis from the upper surface of the flexible baseband, and the left and right ends of the first heat flow sensitive functional layer along the x-axis direction are respectively provided with electrodes; The growth inclination angles of the first directional growth layer, the first interface modification layer and the first heat flow sensitive functional layer are θ1; The second sensing structure comprises a second directional growth layer, a second interface modification layer and a second heat flow sensitive functional layer arranged sequentially and upwardly along the z-axis from the upper surface of the flexible baseband, and the left and right ends of the second heat flow sensitive functional layer along the x-axis direction are respectively provided with electrodes; The left end electrode of the first heat flow sensitive functional layer is connected with the left end electrode of the second heat flow sensitive functional layer, or the right end electrode of the first heat flow sensitive functional layer is connected with the right end electrode of the second heat flow sensitive functional layer; The growth inclination angles of the second directional growth layer, the second interface modification layer and the second heat flow sensitive functional layer are θ2; The growth inclination angle is the angle between the growth baseline (i.e. the lattice c-axis) and the normal projection of the upper surface of the flexible baseband in the xz plane; θ1 and θ2 satisfy θ1 = - θ2; Further, 0° < θ1 < 90°.
[0007] Further, the materials of the first directional growth layer and the second directional growth layer are bidirectional tilt-oriented MgO films, the first interface modification layer and the second interface modification layer are MgO films grown bidirectionally and parallelly along the tilt direction of the MgO directional layer, and the first heat flow sensitive functional layer and the second heat flow sensitive functional layer are LCMO films.
[0008] The present application also provides a preparation method of the flexible baseband differential atomic layer thermoelectric pile heat flow sensor, comprising the following steps: Step one: using a mask to shield the flexible baseband twice, sequentially depositing by electron beam evaporation process, adjusting the angle between the growth baseline and the baseband, and respectively forming a first directional growth layer with a growth inclination angle of θ1 and a second directional growth layer with a growth inclination angle of θ2 on the surface of the baseband, θ1 and θ2 satisfy θ1 = - θ2; Step two: by chemical vapor deposition process, epitaxially growing an interface modification layer with the same composition as the directional growth layer on the surface of the first directional growth layer and the second directional growth layer to reduce the surface roughness of the directional growth layer; Step three: again through chemical vapor deposition process, epitaxial growth of the first heat flow sensitive film with θ1 tilt angle and the second heat flow sensitive film with -θ1 tilt angle on the interface modification layer; Step four: preparing electrodes on the first heat flow sensitive film and the second heat flow sensitive film, and realizing electrical connection between the first heat flow sensitive film and the second heat flow sensitive film through a transmembrane electrode interconnection structure.
[0009] Further, the step one comprises: (1.1) fixing the substrate on the evaporation chamber sample holder at a specific tilt angle, completing the first deposition of the first sensing structure area, and forming a first directional growth layer; (1.2) adjusting the tilt angle of the substrate to the opposite number, completing the first deposition of the second sensing structure area, and forming a second directional growth layer.
[0010] The step two comprises: According to the growth tilt angle of step one, the metal Mg organic source is weighed according to a predetermined proportion, dissolved in tetrahydrofuran to form a precursor solution, and MgO interface modification layers are epitaxially grown on the first sensing structure area and the second sensing structure area by chemical vapor deposition at a high temperature of 630 DEG C.
[0011] The step three comprises: the La, Ca and Mn metal organic sources are weighed according to a predetermined proportion, and LCMO functional layer thin films are epitaxially grown by chemical vapor deposition at a high temperature of 830 DEG C.
[0012] The step four comprises: The high-purity platinum paste is coated on both ends of the thin film, heated at 150 DEG C for 0.5 hours, and then connected to platinum wires to form electrodes after the platinum paste is softened.
[0013] The step five further comprises: heating to a sintering temperature of 950 DEG C at a rate of 5 DEG C / min, keeping the temperature for 0.5 hours, and then cooling at a rate of 5 DEG C / min.
[0014] The ALTP sensor is prepared on a flexible strip-shaped substrate, and the innovative compensation structure and method can effectively suppress the parasitic signal introduced by the traditional Seebeck effect (SEB). U SE The voltage gain and sensitivity are improved, the detection ability of weak heat flow signals is enhanced, the sensor can still obtain reliable measurement in a complex temperature field, and the application range is expanded. In addition, the preparation process based on the strip-shaped substrate only needs two growths to realize the double-oriented thermoelectric structure, which greatly simplifies the process and reduces the cost. BRIEF DESCRIPTION OF DRAWINGS
[0015] Figure 1 It is an atomic layer thermoelectric stack heat flow sensor structure based on a flexible base strip and a differential structure for realizing error compensation.
[0016] Figure 2 A relationship orientation map for the two deposited MgO oriented layers.
[0017] Figure 3 A process flow chart for fabricating the atomic layer thermopile heat flux sensor.
[0018] Figure 4 An out-of-plane Chi scanning curve for the heat flux sensitive chip 1. DETAILED DESCRIPTION
[0019] The technical solutions of the present application will be described in detail below with reference to the accompanying drawings and embodiments.
[0020] Referring to Figure 1 , the present application proposes an atomic layer thermopile heat flux sensor based on a flexible baseband and differential structure to realize error compensation, which comprises a flexible baseband 2 and a first sensing structure and a second sensing structure arranged on the flexible baseband, The first sensing structure comprises a first oriented growth layer 3, a first interface modification layer 4, a first heat flux sensitive film 5, and electrodes 9 and 10 arranged at both ends of the first heat flux sensitive film 5.
[0021] The second sensing structure comprises a second oriented growth layer 6, a second interface modification layer 7, a second heat flux sensitive film 8, and electrodes 11 and 12 arranged at both ends of the second heat flux sensitive film 8.
[0022] The first heat flux sensitive film and the second heat flux sensitive film have the same size and material composition, the same inclination angle, and opposite directions.
[0023] The heat flux sensitive films 5 and 8 are electrically isolated, U SE have the same direction, U TSE have opposite directions.
[0024] The electrode 10 of the first heat flux sensitive film 5 is electrically connected with the electrode 11 of the second heat flux sensitive film 8.
[0025] The voltage value after gain can be obtained by measuring the voltage between the electrodes 9 and 12.
[0026] The preparation method comprises the following steps: Step one, providing a strip, using a mask to shield the strip twice, and sequentially depositing thin films by an electron beam evaporation process to form a first oriented growth layer with a +θ inclination angle and a second oriented growth layer with a -θ inclination angle on the upper and lower parts of the surface of the strip, respectively. Step 2: Using chemical vapor deposition, an interface modification layer with the same composition as the directional growth layer is epitaxially grown on the surfaces of the first and second directional growth layers to reduce the surface roughness of the directional growth layers. Step 3: On the interface modified layer, a first heat flow sensitive film with an θ tilt angle and a second heat flow sensitive film with a -θ tilt angle are epitaxially grown again by chemical vapor deposition. Step four: Electrodes are fabricated on the first heat flow sensitive film and the second heat flow sensitive film, and electrical connection between the first heat flow sensitive film and the second heat flow sensitive film is achieved through a transmembrane electrode interconnection structure.
[0027] Test: Obtain the gain signal by measuring the output voltage. Counteracting the traditional Seebeck effect ( U SE This parasitic interference is eliminated, and a double voltage gain is achieved.
[0028] The voltage between electrode 9 and electrode 12. Similarly; It is a component of the Seebeck coefficient tensor, representing the temperature gradient along the z-direction. The contribution coefficient of the electric field generated in the x direction; It is the temperature gradient of the functional layer film along the z-axis (thickness) direction, representing the temperature difference between the upper and lower surfaces of the film.
[0029] Example 1 This embodiment of the atomic layer thermopile heat flow sensor, based on a flexible substrate and differential structure for error compensation, utilizes the lateral Seebeck effect, requiring only one ALTP material—LCMO thin film—as its sensing element. When LCMO is grown bidirectionally on the same substrate at an angle, its differential structure can not only offset the traditional Seebeck effect (… U SE This parasitic interference can also achieve voltage signal ( U TSE Gain.
[0030] like Figure 1 As shown, structurally, this embodiment specifically includes a first sensing structure and a second sensing structure arranged side by side along the y-axis on the flexible baseband 2. The first sensing structure includes a first oriented growth layer 3, a first interface modification layer 4 and a first heat flow sensitive functional layer 5 sequentially overlapped from the upper surface of the flexible baseband along the z-axis. Electrodes are respectively provided at the left and right ends of the first heat flow sensitive functional layer 5 along the x-axis. The growth inclination angle of the first directional growth layer 3, the first interface modification layer 4 and the first heat flow sensitive functional layer 5 is θ1. The upper surface of the base strip is parallel to the xy plane.
[0031] The second sensing structure comprises, in order from top to bottom along the z axis, a second directional growth layer 6, a second interface modification layer 7 and a second heat flow sensitive functional layer 8, and the second heat flow sensitive functional layer 8 is provided with electrodes at the left and right ends along the x axis direction. The left end electrode of the first heat flow sensitive functional layer 5 is connected to the left end electrode of the second heat flow sensitive functional layer 8, or the right end electrode of the first heat flow sensitive functional layer 5 is connected to the right end electrode of the second heat flow sensitive functional layer 8. The growth inclination angle of the second directional growth layer 6, the second interface modification layer 7 and the second heat flow sensitive functional layer 8 is θ2. The growth inclination angle is the angle between the growth baseline (i.e. the lattice c axis) and the normal projection of the upper surface of the flexible base strip on the xz plane. θ1 and θ2 satisfy θ1 = - θ2; further, 0° < θ1 < 90°.
[0032] The MgO directional growth layer is bidirectional tilt orientation, the interface modification layer is a MgO thin film grown in bidirectional parallel epitaxy along the tilt direction of the MgO directional layer, and the functional layer is a LCMO thin film grown in bidirectional parallel epitaxy along the tilt direction of the MgO interface modification layer.
[0033] Figure 1 In the figure, arrow A shows the tilt direction of the first sensing structure, and arrow B shows the tilt direction of the second sensing structure.
[0034] Figure 2 In the figure, left and right show the cases where the inclination angle is θ and -θ respectively, and left and right represent different tilt directions.
[0035] As shown in Figure 3 The preparation process of the atomic layer thermoelectric pile heat flow sensor based on the flexible base strip and the differential structure to realize error compensation includes: Step 1: deposit MgO directional growth layers with the same inclination angle and opposite directions by electron beam evaporation.
[0036] A mask plate with symmetrical design is used to shield the strip twice, and MgO directional growth layers are deposited in turn. The specific process steps are as follows: first, fix the substrate on the evaporation chamber sample holder at a specific inclination angle, complete the first deposition; then, adjust the inclination angle of the substrate to the opposite number, and perform the second deposition.
[0037] Step 2: epitaxially deposit an MgO interface modification layer on the MgO directional growth layer. The metal Mg organic source is proportionally weighed, dissolved in tetrahydrofuran to form a precursor solution. The MgO interface modification layer is epitaxially grown at a high temperature of 630 DEG C by chemical vapor deposition, so as to reduce the roughness of the oriented layer and improve the crystalline quality of the functional layer.
[0038] Step 3, epitaxially growing the LCMO functional layer on the MgO interface modification layer; The La, Ca and Mn metal organic sources are proportionally weighed, and the LCMO functional layer film is epitaxially grown at a high temperature of 830 DEG C by chemical vapor deposition.
[0039] Step 4, the sample obtained in step 3 is subjected to electrode introduction to prepare metal electrodes on both sides.
[0040] The high-purity platinum paste is coated on both sides of the film, and the film is placed on a heating table at 150 DEG C for 0.5 hours. After the platinum paste is softened, the platinum wire is adhered Step 5, the sample obtained in step 4 is subjected to high-temperature sintering, and the temperature is increased to a sintering temperature of 950 DEG C at a rate of 5 DEG C / min, and the temperature is kept for 0.5 hours. Then the temperature is decreased at a rate of 5 DEG C / min to avoid electrode falling off and film damage caused by thermal stress Step 6, the sample obtained in step 4 is tested.
[0041] As shown in Figure 4 , the sample is subjected to XRD testing to determine the tilt direction of the LCMO functional layer film.
[0042] Through the above systematic study, it can be concluded that the embodiment adopts the electron beam evaporation technology to prepare MgO oriented growth layers with opposite tilt angles on the same strip. On this basis, through high-temperature chemical vapor epitaxy method, the MgO interface modification layer with interface modification function is first deposited and grown, and then the LCMO functional layer with thermoelectric properties is epitaxially grown. The platinum metal electrode is prepared for the obtained sample, and the sintering annealing process is optimized to improve the electrode contact performance.
[0043] The experimental results prove that the preparation process is simple and has good repeatability. The obtained device not only maintains the original sensitivity of the sensor while suppressing the U SE interference, but also significantly improves the output voltage. This design enhances the detection capability of weak heat flow signals, enabling the sensor to still measure stably in a complex temperature field and expanding the detection range. The simple process flow helps to reduce costs, broaden application scenarios, and is especially suitable for heat flow measurement in extreme environments such as aerospace engine thermal protection and nuclear reactor monitoring, which conforms to the current technology development trend.
Claims
1. A flexible baseband differential atomic layer thermopile heat flux sensor, characterized in that, The first sensing structure and the second sensing structure are arranged side by side on the flexible substrate along the y-axis direction. The first sensing structure includes a first oriented growth layer (3), a first interface modification layer (4) and a first heat flow sensitive functional layer (5) that are sequentially overlapped from the upper surface of the flexible substrate along the z-axis direction. Electrodes are respectively provided at the left and right ends of the first heat flow sensitive functional layer (5) along the x-axis direction. The growth tilt angle of the first directional growth layer (3), the first interface modification layer (4) and the first heat flow sensitive functional layer (5) is θ1; The second sensing structure includes a second oriented growth layer (6), a second interface modification layer (7), and a second heat flow sensitive functional layer (8) sequentially stacked from the upper surface of the flexible substrate along the z-axis. Electrodes are respectively provided at the left and right ends of the second heat flow sensitive functional layer (8) along the x-axis. The left electrode of the first heat flow sensitive functional layer (5) is connected to the left electrode of the second heat flow sensitive functional layer (8), or the right electrode of the first heat flow sensitive functional layer (5) is connected to the right electrode of the second heat flow sensitive functional layer (8). The growth tilt angle of the second directional growth layer (6), the second interface modification layer (7), and the second heat flow sensitive functional layer (8) is θ2; The growth tilt angle is the angle between the growth baseline and the projection of the normal to the upper surface of the flexible substrate onto the xz plane; θ1 and θ2 satisfy θ1 = -θ2.
2. The flexible baseband differential atomic layer thermopile heat flux sensor as described in claim 1, characterized in that, θ1 satisfies: 0°<θ1<90°.
3. The flexible baseband differential atomic layer thermopile heat flux sensor as described in claim 1, characterized in that, The first and second oriented growth layers are made of bidirectional tilted MgO thin films. The first and second interface modification layers are bidirectional parallel epitaxially grown MgO thin films along the tilt direction of the MgO oriented layer. The first and second heat flow sensitive functional layers are LCMO thin films.
4. The method for fabricating a flexible baseband differential atomic layer thermopile heat flux sensor as described in claim 1, characterized in that, Includes the following steps: Step 1: The flexible substrate is shielded twice using a mask, and deposited sequentially using an electron beam evaporation process. The angle between the growth baseline and the substrate is adjusted to form a first directional growth layer with a growth tilt angle of θ1 and a second directional growth layer with a growth tilt angle of θ2 on the substrate surface, respectively. θ1 and θ2 satisfy θ1 = -θ2. Step 2: Using chemical vapor deposition, an interface modification layer with the same composition as the directional growth layer is epitaxially grown on the surfaces of the first and second directional growth layers to reduce the surface roughness of the directional growth layers. Step 3: On the interface modified layer, a first heat flow sensitive film with an θ1 tilt angle and a second heat flow sensitive film with a -θ1 tilt angle are epitaxially grown again by chemical vapor deposition. Step 4: Electrodes are fabricated on the first heat flow sensitive film and the second heat flow sensitive film, and electrical connection between the first heat flow sensitive film and the second heat flow sensitive film is achieved through a transmembrane electrode interconnection structure.
5. The method for fabricating a flexible baseband differential atomic layer thermopile heat flux sensor as described in claim 4, characterized in that, Step one includes: (1.1) Fix the substrate at a specific tilt angle onto the sample holder in the evaporation chamber to complete the first deposition of the first sensing structure region and form the first directional growth layer; (1.2) Adjust the substrate tilt angle to the opposite number to complete the first deposition of the second sensing structure region and form the second directional growth layer.
6. The method for fabricating a flexible baseband differential atomic layer thermopile heat flux sensor as described in claim 4, characterized in that, Step two includes: Metallic Mg organic source is weighed according to a predetermined ratio, dissolved in tetrahydrofuran and mixed to form a precursor solution. Chemical vapor deposition is used to modify the MgO interface layer of the first and second sensing structure regions at a high temperature of 630°C and according to the growth tilt angle of step one.
7. The method for fabricating a flexible baseband differential atomic layer thermopile heat flux sensor as described in claim 6, characterized in that, Step three includes: weighing La, Ca, and Mn metal-organic sources according to a predetermined ratio, and using chemical vapor deposition to epitaxially deposit an LCMO functional layer film at a high temperature of 830°C.
8. The method for fabricating a flexible baseband differential atomic layer thermopile heat flux sensor as described in claim 6, characterized in that, Step four includes: High-purity platinum paste is coated on both ends of the film and heated at 150°C for 0.5 hours. After the platinum paste softens, platinum wires are connected to form electrodes.
9. The method for fabricating a flexible baseband differential atomic layer thermopile heat flux sensor as described in claim 6, characterized in that, It also includes step five: The temperature is increased to 950℃ at a rate of 5℃ / min, held for 0.5 hours, and then decreased at a rate of 5℃ / min.