Low-power-consumption thin-film resistance type hydrogen sensor and preparation method thereof

Abstract

The invention belongs to the technical field of sensors, and relates to a low-power-consumption thin-film resistance type hydrogen sensor and a preparation method thereof. The hydrogen sensor comprises a nano array hydrogen sensor, a resistor and a storage capacitor, the branch where the nano array hydrogen sensor is located is connected in parallel with the branch where the storage capacitor is located; a branch where the nano array hydrogen sensor is located is provided with a resistor in series; and a branch where the nano array hydrogen sensor is located and a branch where the storage capacitor is located are powered by a power supply. When the nano-array hydrogen sensor is excited by hydrogen, the nano-array hydrogen sensor is subjected to electrochemical reaction to become a conductor, and a storage capacitor is used as a power supply, so that low-power-consumption work of the nano-array hydrogen sensor is realized; by controlling the working voltage within the set range, it can be ensured that the capacitor can rapidly reach a stable state in each charging and discharging process, so that the response speed and efficiency of the whole circuit are improved, and the resistance value obtained through bridge measurement is more accurate and stable.

Description

Technical Field

[0001] The present invention belongs to the technical field of sensors, and more particularly, relates to a low-power thin-film resistive hydrogen sensor and a preparation method thereof. Background Art

[0002] With the rapid development of sensor detection technology, sensors, as the core components for data acquisition, are increasingly widely used in various fields. However, the large-scale deployment of sensors has also brought the problem of energy consumption. Especially in some fieldwork scenarios, how to effectively save energy has become a research hotspot.

[0003] Traditional energy-saving technologies mainly achieve energy-saving effects by reducing the power consumption of acquisition chips and other components to the lowest level, but this method faces bottlenecks after reaching a certain level and can hardly further improve the energy-saving effect. Although these methods have indeed achieved significant energy-saving effects in the initial stage, obvious bottlenecks have been encountered in further optimizing and improving energy efficiency. For example, when the chip power consumption has been reduced to a very low level, the space for further reducing power consumption is very limited; while the deep sleep mode saves energy but affects the overall performance of the system. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a low-power thin-film resistive hydrogen sensor and a preparation method thereof.

[0005] In a first aspect, the present invention provides a low-power thin-film resistive hydrogen sensor, including a nanoarray hydrogen sensor, a resistor, and a storage capacitor; the branch where the nanoarray hydrogen sensor is located is in parallel with the branch where the storage capacitor is located; a resistor is serially arranged in the branch where the nanoarray hydrogen sensor is located; the branch where the nanoarray hydrogen sensor is located and the branch where the storage capacitor is located are powered by a power supply; When there is no hydrogen, the nanoarray hydrogen sensor is in an insulating state; when there is hydrogen, the nanoarray hydrogen sensor undergoes an electrochemical reaction to conduct, the storage capacitor enters a charging state, and after the charging is completed, the power supply is turned off, and the storage capacitor enters a discharging state to supply power to the branch where the nanoarray hydrogen sensor is located; after the storage capacitor discharges for a set time, the power supply is turned on again so that the storage capacitor re-enters the charging state.

[0006] In a second aspect, the present invention provides a preparation method for a low-power thin-film resistive hydrogen sensor, including: A first thin film layer is provided on a base layer, and an insulating layer is provided after exposure and etching according to the circuit of the low-power thin-film resistive hydrogen sensor; A second thin film layer is provided above the insulating layer to form electrodes of the resistor and the capacitor, as well as connection electrodes and connections of the nanoarray hydrogen sensor; A polyimide layer is provided on the second thin film layer, and nano-grooves are processed to provide a substrate template for the formation of a nano-array palladium nano-film. The palladium nano-film is fabricated using the nano-grooves.

[0007] Based on the above technical solutions, the present invention can be further improved as follows.

[0008] Further, the branch formed by connecting the nano-array hydrogen sensor in series with a resistor is connected in parallel with a storage capacitor.

[0009] Further, the resistance value of the resistor is a set ratio of the resistance value of the nano-array hydrogen sensor.

[0010] Further, the time constant of the storage capacitor is the product of the sum of the nano-array hydrogen sensor and the resistor and the capacitance value of the storage capacitor; the power supply is controlled to be turned on and off according to the time constant, and the voltage of the storage capacitor is maintained at a set ratio of the fully charged and discharged voltage.

[0011] Further, the storage capacitor is connected in parallel at both ends of a group of resistors and then connected in series with another resistor to form a first parallel branch; the branch where the nano-array hydrogen sensor is located is connected in parallel with the first parallel branch across the power supply.

[0012] Further, the capacitance value of the storage capacitor is determined according to the resistance value change range of the nano-array hydrogen sensor.

[0013] Further, the storage capacitor is connected in parallel with the branch where the nano-array hydrogen sensor is located, and the storage capacitor is also connected in parallel with the branch where the resistor is located.

[0014] Further, the resistance ratio of the resistor to the nano-array sensor is between 1:10 and 1:1000.

[0015] Further, the insulating layer is glass or a flexible substrate; the second thin film layer is formed by depositing a molybdenum or copper film on the insulating layer; the polyimide layer is formed by one of spin coating, transfer printing, and spraying; the polyimide is physically rubbed or exposed to ultraviolet light to form nano-grooves.

[0016] The beneficial effects of the present invention are as follows: The present invention utilizes the fact that the nano-array hydrogen sensor is in a relatively insulating state without hydrogen excitation, and no current is generated in the circuit. When hydrogen is present, the nano-array hydrogen sensor undergoes an electrochemical reaction and becomes a conductor. Using the storage capacitor as the power supply, low-power operation of the nano-array hydrogen sensor is achieved; by controlling the working voltage within a set range, it can ensure that the capacitor can quickly reach a stable state during each charge and discharge process, thereby improving the response speed and efficiency of the entire circuit; using the storage capacitor as the power supply can alleviate voltage instability caused by power supply fluctuations or environmental temperature changes, making the resistance value obtained by bridge measurement more accurate and stable. Description of the Drawings

[0017] Figure 1 It is the circuit schematic diagram of a low-power thin-film resistive hydrogen sensor provided by an optional implementation manner of the embodiment of the present invention; Figure 2 It is the sensor circuit design diagram based on a bridge circuit provided by an optional implementation manner of Embodiment 1 of the present invention; Figure 3 It is the sensor circuit design diagram based on a bridge circuit provided by an optional implementation manner of Embodiment 1 of the present invention; Figure 4 It is the preparation method of the low-power thin-film resistive hydrogen sensor provided by Embodiment 2 of the present invention; Figure 5 It is the schematic plan view of the double-layer structure hydrogen sensor provided by Embodiment 2 of the present invention; Figure 6 It is the film layer stack diagram of the double-layer structure hydrogen sensor provided by Embodiment 2 of the present invention; Figure 7 It is the plan view of the single-layer structure hydrogen sensor provided by Embodiment 2 of the present invention; Figure 8 It is the stack diagram of the single-layer structure hydrogen sensor provided by Embodiment 2 of the present invention.

[0018] Icons: R1 - First resistor; R2 - Second resistor; R3 - Third resistor; R4 - Fourth resistor; R5 - Fifth resistor; Rs - s-th resistor; Rs1 - s1-th resistor; RX - Nanorod array hydrogen sensor; RX1 - First nanorod array hydrogen sensor; RX2 - Second nanorod array hydrogen sensor; C - Capacitor; C1 - First capacitor; C2 - Second capacitor; U11 - First input port; U12 - First output port; U21 - Second input port; U22 - Second output port. Detailed Embodiments

[0019] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, 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 some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0020] Embodiment 1 As an embodiment, to solve the above technical problems, this embodiment provides a low-power thin-film resistive hydrogen sensor, including a nanoarray hydrogen sensor, a resistor, and a storage capacitor; the branch where the nanoarray hydrogen sensor is located is connected in parallel with the branch where the storage capacitor is located; a resistor is serially arranged in the branch where the nanoarray hydrogen sensor is located; the branch where the nanoarray hydrogen sensor is located and the branch where the storage capacitor is located are powered by a power supply; When there is no hydrogen, the nanoarray hydrogen sensor is in an insulating state; when there is hydrogen, an electrochemical reaction occurs in the nanoarray hydrogen sensor to conduct, and the storage capacitor enters a charging state. After charging is completed, the power supply is turned off, and the storage capacitor enters a discharging state to supply power to the branch where the nanoarray hydrogen sensor is located; after the storage capacitor discharges for a set time, the power supply is turned on again so that the storage capacitor re-enters the charging state.

[0021] The present invention utilizes that the nanoarray hydrogen sensor is in a relatively insulating state without hydrogen excitation, and no current is generated in the circuit. When there is hydrogen excitation, an electrochemical reaction occurs in the nanoarray hydrogen sensor to become a conductor, and current flows through. The storage capacitor stores charges. When the charge stored in the storage capacitor reaches the power supply voltage, the storage capacitor starts to act as a power supply, thereby realizing the low-power function.

[0022] As shown in the attached Figure 1 circuit schematic diagram of the low-power thin-film nanoarray hydrogen sensor, VCC represents the power supply, OUT represents the output terminal of the low-power thin-film resistive hydrogen sensor, GND represents the grounding terminal, R1 represents the first resistor, RX represents the nanoarray hydrogen sensor. Based on the constant current source circuit test, the circuit parameters of the hydrogen sensor are optimized to achieve the low-power design. When the storage capacitor is connected in parallel with the resistance to be measured, due to the energy storage characteristic of the storage capacitor, it can alleviate the voltage instability caused by power supply fluctuations or environmental temperature changes, so that the resistance value obtained by the bridge measurement is more accurate and stable. At the same time, because the capacitor can accumulate charges at both ends, even if the external power supply is interrupted briefly or the voltage drops, relying on the stored energy, the circuit can still maintain a normal working state for a period of time without stopping immediately, thereby achieving the purpose of energy saving.

[0023] As an optional implementation manner, the branch after the nanoarray hydrogen sensor is serially connected with the resistor is connected in parallel with the storage capacitor.

[0024] The nanoarray hydrogen sensor is serially connected with the resistor, so that the current flowing through the nanoarray hydrogen sensor and the resistor is exactly the same, thus forming an accurate proportional relationship. For example, when the resistance value of the nanoarray hydrogen sensor is 100 Ω, the resistance value of the resistor should be 1 Ω. By setting the proportional relationship, the signal change of the highly sensitive nano hydrogen sensor can be effectively reflected.

[0025] Optionally, the resistance value of the resistor is a set ratio of the resistance value of the nanoarray hydrogen sensor.

[0026] As an optional implementation manner, the resistance value of the resistor is 0.1% - 10% of the resistance value of the nano hydrogen sensor (when the nano hydrogen sensor is in a stable state), which can ensure the provision of a stable reference resistor and make the entire circuit more sensitive to changes in hydrogen concentration.

[0027] In the actual application process, the selection of the capacitor corresponding to the storage capacitor needs to consider multiple factors. If the capacitance value of the capacitor is too small, it will lead to too high a power supply switching frequency, thereby increasing the switching loss and electromagnetic interference, affecting the stability and reliability of the system; on the contrary, if the capacitance value of the capacitor is too large, although the switching frequency can be reduced, the manufacturing process will become more complex, increasing the cost and volume, and at the same time, more parasitic effects will be introduced, such as lead inductance and distributed capacitance, which will all affect the overall performance of the circuit.

[0028] Optionally, the time constant of the storage capacitor is the product of the sum of the nanoarray hydrogen sensor and the resistor and the capacitance value of the storage capacitor; the power supply is turned on and off according to the time constant, and the voltage of the storage capacitor is maintained at a set ratio of the fully charged and discharged voltage.

[0029] The total resistance of the nanoarray hydrogen sensor RX and the first resistor R1 is R. The time constant t of the capacitor C is t = R ⋅ C, and R = RX + R1. Since the resistance value of the nanoarray hydrogen sensor RX is much larger than that of the first resistor R1, the total resistance R is mainly determined by RX. By selecting a capacitor with an appropriate capacitance value, it can ensure that the time constant t is moderate, which will neither cause too high a switching frequency nor make the film manufacturing process complex. The selection of the capacitance value should be based on the required response time and stability requirements. To ensure that the circuit operates in the best state, the voltage is controlled to operate between 0.63 μV and 0.95 μV. This range of selection is based on the charge and discharge characteristics of the capacitor. According to the charge and discharge formula of the RC circuit, the time of the charge and discharge process of the capacitor and the voltage are such that after a time constant t = R ⋅ C, the voltage reaches about 63% of the final voltage, that is, 0.63 μV. When the voltage reaches 0.95 μV, the capacitor is fully charged or discharged, and the working efficiency is the highest at this time, and the charge and discharge time is the shortest. Controlling the working voltage in the range of 0.63 μV to 0.95 μV can ensure that the capacitor can quickly reach a stable state during each charge and discharge process, thereby improving the response speed and efficiency of the entire circuit. Let the six time points during the capacitor charging time be t1, t2, t3, t4, t5, and t6, and the corresponding voltages be V1, V2, V3, V4, V5, and V6. The relationship between the capacitor charging time and the voltage, that is, the voltage corresponding to the time constant is as follows: When t1 = RC, V1 = 0.63 μV; when t2 = 2RC, V2 = 0.86 μV; when t3 = 2RC, V3 = 0.86 μV; when t4 = 3RC, V4 = 0.95 μV; when t5 = 4RC, V5 = 0.98 μV; when t6 = 5RC, V6 = 0.99 μV. When the resistance value RX (in the stable state) of the highly sensitive nano hydrogen sensor is 10 M, then the resistance value of the first resistor R1 can be calculated as 100 K through 100:1, and R = (R1 + RX) = 10.1 M. When charging once per second, establish the equation: 1 = 3RC; C = 1 / 3R; C = 1 / (3 * 10.1 M); C = 33 nF. From this, it can be calculated that when C = 33 nF, it can meet the requirement of charging once per second and the voltage operating between 0.63 μV and 0.95 μV. 86058635 As an alternative implementation, the storage capacitor is connected in parallel across a group of resistors and then connected in series with another resistor to form the first parallel branch; the branch where the nanoarray hydrogen sensor is located is connected in parallel with the first parallel branch across the power supply.

[0030] Optionally, the capacitance of the storage capacitor is determined according to the resistance value change range of the nanoarray hydrogen sensor.

[0031] The parallel capacitors can be determined by the resistance change range of the sensor. When used on sensors with a relatively large resistance change, capacitors with a relatively large capacitance are paralleled, and vice versa for capacitors with a relatively small capacitance. Selecting capacitors in this way can enable the sensor detection circuit to achieve energy savings without spending a large amount of computing power to calculate the change curve of the capacitor voltage. A capacitor C is paralleled across the two ends of the nanoarray hydrogen sensor RX, and at the same time, the bridge circuit is equivalently obtained as shown in the appendix Figure 2 The circuit shown. R1, R2, and Rs represent resistors. Specifically, R1 is the first resistor, R2 is the second resistor, and Rs is the s-th resistor. Based on the bridge circuit, the first resistor R1, the second resistor R2, the nanoarray hydrogen sensor RX, and the s-th resistor Rs form a bridge structure. After the second resistor R2 and the s-th resistor Rs are connected in series, they are connected in parallel with the branch where the series branch of the first resistor R1 and the nanoarray hydrogen sensor RX is located, and the capacitor C is paralleled across the two ends of the nanoarray hydrogen sensor RX.

[0032] As an alternative implementation, the storage capacitor is paralleled with the branch where the nanoarray hydrogen sensor is located, and the storage capacitor is also paralleled with the branch where the resistor is located. As shown in the appendix Figure 3 shown. Based on the bridge circuit, the first resistor R1, the second resistor R2, the nanoarray hydrogen sensor RX, and the s-th resistor Rs form the four arms of the bridge structure. The second resistor R2 is connected in series with the s-th resistor Rs, and the nanoarray hydrogen sensor RX is connected in series with the first resistor R1. After the second resistor R2 and the s-th resistor Rs are connected in series, they are connected in parallel with the series branch of the first resistor R1 and the nanoarray hydrogen sensor RX and the branch where the capacitor C is located, obtaining a low-power nanoarray hydrogen sensor bridge circuit.

[0033] Optionally, the resistance ratio of the resistor to the nanoarray sensor is between 1:10 and 1:1000.

[0034] Such a ratio design makes the voltage drop across the nanoarray hydrogen sensor much larger than that of the resistor, thus effectively reflecting the signal changes of the highly sensitive nano hydrogen sensor.

[0035] Embodiment 2 Based on the same principle as the method shown in Embodiment 1 of the present invention, as shown in the appendix Figure 4 shown, the embodiment of the present invention also provides a method for fabricating a low-power thin-film resistor type hydrogen sensor, including: A first thin film layer is provided on the base layer, and an insulating layer is provided after exposure and etching according to the circuit of the low-power thin-film resistor type hydrogen sensor; A second thin film layer is provided above the insulating layer to form the electrodes of the resistor and the capacitor, as well as the wiring electrodes and wiring of the nanoarray hydrogen sensor; A polyimide layer is provided on the second thin film layer, and nano-grooves are processed to provide a substrate template for the formation of the nanoarray palladium nano-film; Fabricating a palladium nanometer thin film by using nano-grooves.

[0036] The present invention realizes a high-precision resistor manufacturing process through thin film technology, which can ensure that the resistance value of the resistor maintains extremely high stability and precision during the production process, making the entire circuit more sensitive to changes in hydrogen concentration.

[0037] Optionally, the insulating layer is glass or a flexible substrate; the second thin film layer is formed by depositing a molybdenum or copper film on the insulating layer; the polyimide layer is formed by one of spin coating, transfer printing, and spraying; physical friction or ultraviolet exposure is performed on the polyimide to form nano-grooves.

[0038] Specifically, when preparing a hydrogen sensor with a bilayer structure, as shown in the appendix Figure 5 When setting the first thin film layer on the base layer, a molybdenum or copper thin film is first made on a glass substrate or a flexible substrate, with a thickness in the range of 100 - 1000 nanometers. Exposure etching is performed according to the circuit diagram designed as shown in the appendix Figure 6 As shown, R3 is the third resistor, RX1 is the first nanoarray hydrogen sensor, C1 is the first capacitor, a first input port U11 is provided on one side of the first capacitor C1, and a first output port U12 is provided on the other side; then an insulating layer with a thickness of 200 - 1000 nanometers is made, and the insulating layer can be silicon nitride or silicon dioxide, and exposure etching is performed according to the circuit drawing, and then a molybdenum or copper thin film is made, which is the same as the requirement of the first thin film layer. The purpose is to form the electrodes of the resistor and capacitor, the wiring electrodes and wiring of the hydrogen sensor. Then a polyimide layer with a thickness of 10 - 200 nanometers is made, which can be formed by spin coating or transfer printing or spraying, and nano-grooves are formed by physical friction or ultraviolet light exposure and other methods to provide a substrate template for the formation of the nanoarray palladium film. Finally, according to the characteristics of the nano-grooves of the substrate material, a palladium thin film with a thickness of 3 - 30 nanometers is fabricated.

[0039] Specifically, when preparing a hydrogen sensor with a monolayer structure, as shown in the appendix Figure 7 As shown, first, a molybdenum or copper film is deposited on a glass or flexible substrate to obtain the first thin film layer, with a thickness of 100 - 1000 nanometers. The purpose is to form as shown in the appendix Figure 8The fourth resistor R4, the fifth resistor R5, the second nanoarray hydrogen sensor RX2, the s1 resistor Rs1, and the electrodes of the second capacitor C2 are shown. A second input port U21 is provided on one side of the second capacitor C2, and a second output port U22 is provided on the other side. Then, an insulating layer of silicon nitride or a silicon dioxide film is fabricated with a thickness of 200 to 1000 nanometers. The purpose is to provide an insulating substrate for the substrate of the second nanoarray hydrogen sensor RX2. Then, a polyimide substrate with a thickness of 10 to 200 nanometers is made. Next, physical friction or ultraviolet exposure is performed on the polyimide to form nano-grooves, providing a substrate template for the formation of the array palladium film. Finally, a 3 to 30 nanometer thin film is fabricated.

[0040] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various modifications and changes can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A low power consumption thin film resistor type hydrogen sensor, characterized in that: It includes a nano-array hydrogen sensor, a resistor and a storage capacitor; the branch where the nano-array hydrogen sensor is located is connected in parallel with the branch where the storage capacitor is located; the branch where the nano-array hydrogen sensor is located is connected in series with a resistor; the branch where the nano-array hydrogen sensor is located and the branch where the storage capacitor is located are powered by a power supply; When there is no hydrogen, the nanoarray hydrogen sensor is in an insulating state; when there is hydrogen, the nanoarray hydrogen sensor undergoes an electrochemical reaction and conducts, and the storage capacitor enters a charging state. After charging is completed, the power is turned off, and the storage capacitor enters a discharging state to supply power to the branch where the nanoarray hydrogen sensor is located; after the storage capacitor discharges for a set time, the power is turned on again to allow the storage capacitor to re-enter a charging state.

2. A low power consumption thin film resistor type hydrogen sensor according to claim 1, characterized in that: The branch after the nano-array hydrogen sensor is connected in series with the resistor is connected in parallel with the storage capacitor.

3. A low power consumption thin film resistor type hydrogen sensor according to claim 2, characterized in that: The resistance value of the resistor is a set ratio of the resistance value of the nano-array hydrogen sensor.

4. A low power consumption thin film resistor type hydrogen sensor according to claim 2, characterized in that: The time constant of the storage capacitor is the product of the sum of the nano-array hydrogen sensor and the resistor and the capacitance value of the storage capacitor; the power supply is turned on and off according to the time constant to keep the voltage of the storage capacitor at a set ratio of the full charge and discharge voltage.

5. A low power consumption thin film resistor type hydrogen sensor according to claim 1, characterized in that: The storage capacitor is arranged in parallel at both ends of a group of resistors and then connected in series with another resistor as a first parallel branch; the branch where the nano-array hydrogen sensor is located is connected in parallel with the first parallel branch at both ends of the power supply.

6. A low power consumption thin film resistor type hydrogen sensor according to claim 5, characterized in that: The capacitance of the storage capacitor is determined according to the resistance variation range of the nano-array hydrogen sensor.

7. A low power consumption thin film resistor type hydrogen sensor according to claim 1, characterized in that: The storage capacitor is connected in parallel with the branch where the nano-array hydrogen sensor is located, and the storage capacitor is connected in parallel with the branch where the resistor is located.

8. A low power consumption thin film resistor type hydrogen sensor according to claim 1, characterized in that: The ratio of the resistor to the resistance of the nanoarray sensor is between 1:10 and 1:1000.

9. A method for preparing a low power consumption thin film resistor type hydrogen sensor based on the low power consumption thin film resistor type hydrogen sensor according to claim 1, characterized in that: include: A first thin film layer is provided on the base layer, and an insulating layer is provided after exposure and etching according to the circuit of the low power consumption thin film resistance type hydrogen sensor; A second thin film layer is disposed above the insulating layer to form electrodes of resistance and capacitance as well as wiring electrodes and wiring of the nano-array hydrogen sensor; A polyimide layer is disposed on the second film layer, and nano-grooves are formed to provide a substrate template for the formation of a nano-array palladium nano-film; Fabrication of palladium nanofilm using nanogrooves.

10. The method for preparing a low-power thin-film resistor type hydrogen sensor according to claim 9, characterized in that: The insulating layer is glass or a flexible substrate; the second thin film layer is arranged by depositing a molybdenum or copper film on the insulating layer; the polyimide layer is arranged by one of spin coating, transfer printing and spray coating; the polyimide is physically rubbed or ultraviolet exposed to form nano grooves.

Images