Micro electrostrictive sensor, device and method for monitoring catalytic reaction

Abstract

The invention discloses a micro electrostriction sensor for monitoring catalytic reaction. The micro electrostriction sensor, a signal processing system and an LED display system jointly form a catalytic reaction monitoring device. The capacitance change caused by the strain change of the material is monitored in real time through the micro electrostriction sensor and is displayed by the LED, so that the intensity change of the catalytic reaction is obtained, the intensity of the catalytic reaction is evaluated in real time in the catalytic process, and the monitoring device and the monitoring method are provided for research on the catalytic reaction of the electrostriction material.

Description

Technical Field

[0001] This application belongs to the fields of microelectromechanical systems and catalytic technologies, and particularly relates to a micro electrostrictive sensor, device, and method for monitoring catalytic reactions. Background Art

[0002] In recent years, catalytic sensors, as the product of the combination of catalytic technology and sensor technology, have become a research hotspot due to advantages such as small size, low cost, and integratability. Existing catalytic sensors detect the changes in physical or chemical signals during the catalytic reaction process to achieve highly sensitive and highly selective detection of specific gases, ions, or biomolecules, but they do not have universality. Traditional catalytic sensors are mostly based on resistive, thermal conductivity, or optical detection principles. However, these existing solutions still have deficiencies in catalytic reaction monitoring: for example, resistive sensors based on the change of material resistance with deformation have low sensitivity and are difficult to detect small physical quantity changes in catalytic reactions; the temperature detection method based on thermocouples needs to indirectly reflect the catalytic reaction heat effect through heat conduction, and the response time is up to several seconds; catalytic sensors based on electrochemical principles need to introduce electrolytes and reference electrodes, increasing the system complexity; although optical sensors can achieve high-precision measurement, they require complex optical path design and signal modulation systems, are difficult to miniaturize and have low cost, and optical components are easily affected by the attachment of pollutants, resulting in insufficient long-term stability. In addition, existing technologies are difficult to achieve spatio-temporal resolved monitoring of catalytic reactions at the micro-nano scale, which limits the in-depth study of the dynamic evolution of catalytic active sites. Therefore, there is an urgent need for a universal real-time monitoring method for catalytic reactions that is low-cost, highly sensitive, fast-responsive, and easy to operate based on miniaturized design. Summary of the Invention

[0003] The purpose of this application is to provide a micro electrostrictive sensor, device, and method for monitoring catalytic reactions, which are based on the signals of the micro electrostrictive sensor to synchronously and directly monitor the strain of the electrostrictive material and the intensity of the catalytic reaction. An electrostrictive material layer and upper and lower electrodes form a strain-sensitive flexible cantilever beam; a capacitor plate is integrated at the free end of the cantilever beam, and a parallel plate capacitor with a variable distance is formed with the fixed plate to achieve efficient coupling of deformation-capacitance. The sensor is placed in the catalytic reaction system, and the physical / chemical changes generated by the reaction are coupled to the electrostrictive material through the strain mechanism; the deformation of the electrostrictive material causes a change in the distance between the capacitor plates, and the change in the capacitance value has a linear relationship with the reaction process, realizing quantitative monitoring of the reaction state. The capacitance signal is modulated and processed to drive the LED array; the LED display system displays different colors according to the change in capacitance, intuitively presenting the catalytic reaction state.

[0004] To achieve the above object, the technical solution adopted by the present invention is as follows: The micro electrostrictive sensor for monitoring catalytic reactions includes a cantilever beam composed of an upper electrode layer 1, a lower electrode layer 6, an electrostrictive layer 7, and a catalytic region 2, a cantilever beam fixing stage 5, an upper electrode plate 3, and a lower electrode plate 4. Among them, the electrostrictive layer 7 is located between the upper and lower electrode layers. The catalytic region 2 is the region on the upper surface of the electrostrictive layer 7 that is not covered by the upper electrode layer. The upper electrode plate 3 is a fixed electrode plate. The free end of the cantilever beam is integrated with the lower electrode plate 4 to form a parallel plate capacitor with a variable distance from the upper electrode plate 3. The catalytic region 2 is the region on the upper surface of the electrostrictive layer that is not covered by the electrode to avoid the influence of electrode coverage on the catalytic reaction. An excitation signal is applied to the upper and lower electrode layers, and strain is generated through the electrostrictive effect of the electrostrictive layer 7. The strain causes the free end of the cantilever beam to swing, changing the distance between the upper and lower electrode plates, thereby changing the capacitance value.

[0005] The micro electrostrictive sensor placed in the catalytic reaction system can be used to monitor the progress of the catalytic reaction.

[0006] In order to more intuitively display the capacitance signal of the catalytic reaction monitored by the micro electrostrictive sensor, the present invention also provides a monitoring device for catalytic reactions. The device includes a micro electrostrictive sensor, a signal processing system, and an LED display system. The catalytic reaction occurs in the micro electrostrictive sensor, and the catalytic reaction causes the capacitance value to change. The signal of the capacitance value change is connected to the signal processing system through a signal probe. The signal processing system and the LED display system are connected in sequence, and the LED display system presents the catalytic reaction state.

[0007] The signal of the capacitance value change is amplified by the signal processing system and then converted into a voltage or current signal and transmitted to the LED display system. The LED display system displays different colors according to the capacitance change amount, presenting the intensity of the catalytic reaction.

[0008] The method for monitoring the catalytic reaction includes the following steps: ① Connect a power supply to the upper and lower electrode layers to achieve DC or AC excitation of the electrostrictive material; ② Start the catalytic reaction. During the catalytic process, the signal processing system monitors the change of the capacitance value in real time through a parameter extraction method based on the micro electrostrictive sensor; ③ Display the capacitance value monitored in step ② through the LED display system. Different colored LED lights represent different capacitance values; ④ Judge the intensity of the catalytic reaction through the color of the LED lights displayed in step ③.

[0009] The method for monitoring the catalytic reaction further includes: in step ①, the alternating voltage frequency of the power supply connected to the upper and lower electrode layers is less than 1 kHz, preferably less than 1 Hz. The electrode layers 1 and 6 can be selected from any one of metal materials with high conductivity such as Au, Pt, Cu, Ag, and Al; the electrostrictive material is a non-classical electrostrictive material and an ionic conductor material with good catalytic activity. The electrostrictive material can be selected from fluorite structure oxide materials such as Gd-doped ceria, Sm-doped ceria, Y-doped zirconia, δ-Bi2O3, or non-fluorite structure oxide materials such as LaMo2O9, LaMoWO9, and MAPbI3.

[0010] Compared with the prior art, the present invention has the following beneficial effects: The present invention monitors the catalytic reaction based on a micro electrostrictive sensor. In principle, it only depends on the electrochemical reaction of the electrostrictive material. Therefore, it can be placed in different gas and liquid environments and can effectively monitor various catalytic reactions, having good universality. Since the magnitude of the monitored capacitance signal is related to the strength of the catalytic reaction, the entire process of the catalytic reaction can be monitored. The capacitance value monitored by the micro electrostrictive sensor of the present invention can be real-time displayed through an LED display system, facilitating the intuitive observation of the catalytic reaction status. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic structural diagram of the catalytic reaction monitoring device based on the micro electrostrictive sensor of the present invention; Figure 2 is a flowchart of the method for monitoring the catalytic reaction based on the micro electrostrictive sensor of the present invention; Figure 3 is a corresponding schematic diagram of the electrostrain magnitude and the catalytic reaction strength in a specific embodiment of the present invention; Figure 4 is a finite element simulation diagram of the change in the displacement of the cantilever beam when the electrostrictive coefficient of the micro electrostrictive sensor changes by one order of magnitude in a specific embodiment of the present invention; Figure 5 is a diagram of the difference in capacitance value caused by the change in the displacement of the cantilever beam when the electrostrictive coefficient of the micro electrostrictive sensor changes by one order of magnitude in a specific embodiment of the present invention; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0012] To make the objectives, technical solutions, and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the specific embodiments and with reference to the accompanying drawings.

[0013] The electrostrictive layer 7 uses Sm-doped CeO2 material, and the electrode layers 1 and 6 use gold electrodes.

[0014] Electrostrictive Displacement Measurement of CeO2 Material with 20% Sm Doping Concentration at Specific Voltage and Frequency: Apply an AC voltage of 140 V and a frequency of 1 Hz to the electrode layer. Under the excitation of the AC voltage, obvious electrochemical reactions occur in the CeO2 material with 20% Sm doping concentration, that is, a large amount of Ce 4+ is reduced to Ce 3+ , and at the same time, as shown in Figure 3 , a displacement response exceeding 30 nm occurs, indicating a large electrostrictive strain at this time. When the electrochemical reaction occurring in the CeO2 material with 20% Sm doping concentration is weak, its displacement response decreases by nearly an order of magnitude, and the displacement size is only about 4 nm at this time, indicating a small electrostrictive strain at this time. It can be seen that the strength of the catalytic reaction is related to the electrostrictive strain size of the CeO2 material with 20% Sm doping concentration.

[0015] The electrostrictive displacement / strain size depends on the electrostrictive coefficient of the material. The deformation of the cantilever beam under different electrostrictive coefficients was analyzed by finite element simulation. Apply a DC voltage of 100 V to the electrode layer. When considering a strong catalytic reaction, set the electrostrictive coefficient M of the electrostrictive layer 7 11 =-5.3x10 -16 m 2 / V 2 , and the displacement |u| of the electrostrictive layer 7 as shown in Figure 4 (a) is obtained. It is found that the maximum displacement of the electrostrictive layer 7 is about 2 μm. When considering a weak catalytic reaction, set the electrostrictive coefficient M of the electrostrictive layer 7 11 =-5.3x10 -17 m 2 / V 2 , and the displacement |u| of the electrostrictive layer 7 as shown in Figure 4 (b) is obtained. It is found that the maximum displacement of the electrostrictive layer 7 is about 0.2 μm, which is reduced by an order of magnitude compared with the displacement value under strong catalytic reaction. This shows that the strength of the electrocatalytic reaction is closely related to the mechanical deformation of the electrostrictive layer in the cantilever beam, and the stronger the catalytic reaction, the more obvious the strain.

[0016] To clarify the influence of the strength of the catalytic reaction on the capacitance of the micro electrostrictive sensor, apply a DC voltage of 100 V to the electrode layer. When considering strong and weak catalytic reactions, set the electrostrictive coefficients of the electrostrictive layer 7 to be M 11 =-5.3x10 -16 m 2 / V 2 and M 11 =-5.3x10 -17 m 2 / V 2After considering the changes in the equivalent area and distance between the upper electrode layer 4 and the upper plate 3 due to the cantilever deformation, the capacitance value of the parallel plate capacitor as shown in Figure 4 was calculated. It was found that when the catalytic reaction was strong, the capacitance value was ~11x10 -16 F, but when the catalytic reaction was weak, the capacitance value dropped to ~7x10 -16 F, a decrease of about 52.7%. This indicates that the micro electrostrictive sensor can effectively monitor the intensity of the catalytic reaction through capacitance changes.

Claims

1. A micro electrostrictive sensor for monitoring catalytic reactions, the micro electrostrictive sensor comprising a cantilever beam composed of an upper electrode layer (1), a lower electrode layer (6), an electrostrictive layer (7), and a catalytic region (2), a cantilever beam fixed stage (5), an upper electrode plate (3), and a lower electrode plate (4), wherein, The electrostrictive layer (7) is located between the upper and lower electrode layers. The catalytic region (2) is the region on the upper surface of the electrostrictive layer (7) that is not covered by the upper electrode layer. The upper electrode plate (3) is a fixed electrode plate. The free end of the cantilever beam is integrated with the lower electrode plate (4), forming a parallel plate capacitor with variable spacing with the upper electrode plate (3).

2. The micro electrostrictive sensor according to claim 1, wherein: Both the upper electrode layer (1) and the lower electrode layer (6) can be selected from any one of metal materials with high conductivity such as Au, Pt, Cu, Ag, Al, etc.

3. The micro electrostrictive sensor according to claim 1 or 2, characterized in that: The electrostrictive material used in the electrostrictive layer (7) is a non-classical electrostrictive material.

4. The micro electrostrictive sensor according to claim 3, characterized in that: The non-classical electrostrictive materials used in the electrostrictive layer (7) are fluorite structure oxide materials such as Gd-doped cerium oxide, Sm-doped cerium oxide, Y-doped zirconia, δ-Bi2O3, etc. or non-fluorite structure oxide materials such as LaMo2O9, LaMoWO9, MAPbI3, etc.

5. The micro electrostrictive sensor according to any one of claims 1-4, characterized in that, An excitation voltage is applied to the upper and lower electrode layers. Strain is generated through the electrostrictive effect of the electrostrictive layer (7). The strain causes the free end of the cantilever beam to swing, changing the distance between the upper and lower electrode plates, thereby changing the capacitance value.

6. A catalytic reaction monitoring device comprising the micro electrostrictive sensor according to any one of claims 1-5, characterized in that, The device further includes a signal processing system and an LED display system. The micro electrostrictive sensor is placed in the catalytic reaction system. The catalytic reaction causes the capacitance value to change. The signal of the capacitance value change is connected to the signal processing system through a signal probe. The signal processing system and the LED display system are connected in sequence, and the LED display system presents the catalytic reaction state.

7. According to the monitoring device described in claim 6, the signal of the capacitance value change is amplified by the signal processing system and then converted into a voltage or current signal and transmitted to the LED display system. The LED display system displays different colors according to the capacitance change amount, presenting the intensity of the catalytic reaction.

8. A method for monitoring a catalytic reaction using the catalytic reaction monitoring device described in claim 7, the catalytic reaction monitoring method includes the following steps: ① Connect a power supply to the upper and lower electrode layers to achieve DC or AC excitation of the electrostrictive material; ② Start the catalytic reaction. During the catalytic process, the signal processing system monitors the change of the capacitance value in real time through a parameter extraction method based on the micro electrostrictive sensor; ③ Display the capacitance value monitored in step ② through the LED display system. Different colored LED lights represent different capacitance values; ④ Judge the intensity of the catalytic reaction through the color of the LED lights displayed in step ③.

9. The monitoring method of the catalytic reaction according to claim 8, characterized in that: In step ①, the alternating voltage frequency of the power supply connected to the upper and lower electrode layers is less than 1 kHz.

10. The monitoring method of the catalytic reaction according to claim 9, characterized in that: In step ①, the alternating voltage frequency of the power supply connected to the upper and lower electrode layers is less than 1 Hz.

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