A flexible thin film sensor

Abstract

The application relates to the technical field of space dust measurement, in particular to a flexible film sensor, which comprises a packaging layer, a fixed substrate, an electrode layer and a sensitive unit, wherein the sensitive unit is a PVDF film; the electrode layer comprises an upper electrode layer and a lower electrode layer, both of which are multilayer superposition structures prepared by a magnetron sputtering process and take the PVDF film as a substrate; the fixed substrate comprises an upper fixed substrate and a lower fixed substrate, the upper fixed substrate is fixedly assembled with the upper electrode layer, and the lower fixed substrate is fixedly assembled with the lower electrode layer; and the packaging layer comprises an upper packaging layer and a lower packaging layer, the upper packaging layer is fixedly connected with the upper fixed substrate through a bolt, and the lower packaging layer is fixedly connected with the lower fixed substrate through a bolt. The application is used for dust momentum characteristic measurement, the sensitivity of the sensor is improved by magnetron sputtering of Au / Cr metal on the PVDF film, and the response layer is a polarized PVDF film, which has a high piezoelectric coefficient.

Description

Technical Field

[0001] This application relates to the field of space dust measurement technology, and more specifically, to a flexible thin-film sensor. Background Technology

[0002] In current lunar and deep space exploration missions, the measurement of high-speed space dust is crucial for understanding the origin and evolution of the universe, the safe operation of spacecraft, and the health of astronauts. However, traditional space dust measurement instruments face a series of challenges, one of which is their large size and weight, leading to lower reliability in long-term space environments.

[0003] Currently used space dust measurement instruments are often too large and heavy, limiting the ability to carry other scientific instruments and experimental equipment. Furthermore, the large size of these measurement devices increases the technical difficulty and risk during spacecraft launch, deployment, and operation. Their size not only increases the mass of the spacecraft but may also cause instability or negatively impact navigation systems, thus hindering the effectiveness of space missions.

[0004] In long-term space environments, these measuring instruments also face extreme temperatures, radiation, and microgravity, which may lead to a gradual decline in instrument performance or even equipment failure. Therefore, in order to improve the accuracy and reliability of space dust measurements, there is an urgent need to develop more compact, lightweight, and advanced measuring instruments suitable for long-term space missions. Summary of the Invention

[0005] This application provides a flexible thin-film sensor for measuring the momentum characteristics of high-speed dust particles in space. It has a short response time, a wide detection range, and can also obtain the velocity value of the dust particles.

[0006] To achieve the above objectives, this application provides a flexible thin-film sensor, including an encapsulation layer, a fixing substrate, an electrode layer, and a sensing element, wherein: the sensing element is a PVDF thin film with a thickness of 8-12 μm; the electrode layer includes an upper electrode layer and a lower electrode layer, the upper electrode layer being disposed above the PVDF thin film and the lower electrode layer being disposed below the PVDF thin film, both the upper and lower electrode layers being multilayer stacked structures fabricated using a magnetron sputtering process based on the PVDF thin film; the fixing substrate includes an upper fixing substrate and a lower fixing substrate, the upper fixing substrate being fixedly assembled with the upper electrode layer and the lower fixing substrate being fixedly assembled with the lower electrode layer; the encapsulation layer includes an upper encapsulation layer and a lower encapsulation layer, the upper encapsulation layer being fixedly connected to the upper fixing substrate by bolts, and the lower encapsulation layer being fixedly connected to the lower fixing substrate by bolts.

[0007] Furthermore, the encapsulation layer is made of aluminum alloy.

[0008] Furthermore, the material for fixing the substrate is glass.

[0009] Furthermore, both the upper and lower electrode layers are composed of stacked Au and Cr layers. The Cr layer is sputtered onto a PVDF thin film substrate and has a thickness of 5-6 nm. The Au layer is sputtered onto the Cr layer and has a thickness of 50-60 nm.

[0010] Furthermore, the PVDF film is prepared using the following steps: Step 1: Dissolve PVDF in an N-methylpyrrolidone solution; Step 2: Apply the mixture to the surface of a silicon wafer by magnetic stirring and spin coating; Step 3: Remove residual bubbles using a vacuum degassing process; Step 4: Evaporate the N-methylpyrrolidone solution by heating to obtain the PVDF film; Step 5: Perform high-voltage thermal polarization treatment on the PVDF film using dimethyl silicone oil as the insulating medium.

[0011] Furthermore, lead wires are provided on the electrode layer, and the lead wires are fixed out using clamps and hollow rivets.

[0012] Furthermore, before PVDF film assembly, it is cleaned with alcohol and deionized water, followed by plasma treatment.

[0013] Furthermore, the measurable velocity range of high-speed dust particles in space is ≥1km / s, and the maximum measurable flux of space dust particles is 1000 particles / m³. 2 •s, sampling rate 300-350kHz.

[0014] Furthermore, the temperature tolerance range is -30°C to +60°C, the stability is 10%, and the response time is <1 second.

[0015] The flexible thin-film sensor provided in this application has the following advantages:

[0016] This application is used for measuring the momentum characteristics of dust. By magnetron sputtering of Au / Cr metal on a PVDF film, the sensitivity of the sensor is improved. At the same time, the response layer is a polarized PVDF film with a high voltage coefficient. The sensor is encapsulated by upper and lower packaging shells made of aluminum alloy, which can not only be installed on the curved surface structure of spacecraft, but also greatly saves the space and weight of the spacecraft. It has the characteristics of short response time, wide measurement range and high measurement accuracy. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application. In the drawings:

[0018] Figure 1 This is a schematic diagram of the structure of a flexible thin-film sensor according to an embodiment of this application;

[0019] Figure 2 This is a schematic diagram illustrating the principle of measuring the momentum characteristics of dust using a flexible thin-film sensor provided in the embodiments of this application.

[0020] Figure 3 This is a flowchart illustrating the fabrication of a PVDF thin film for a flexible thin-film sensor according to an embodiment of this application.

[0021] Figure 4 This is a schematic diagram of the PVDF film of the flexible thin-film sensor provided in the embodiments of this application undergoing high-voltage thermal polarization;

[0022] Figure 5 This is a display diagram showing the signal response of a flexible thin-film sensor under the impact of thermoplastic polyurethane (TPU) particles;

[0023] Figure 6 This is an actual reference diagram showing the fixing of the lead wires of the flexible thin-film sensor according to the embodiments of this application;

[0024] In the figure: 1-sensing unit, 2-upper electrode layer, 3-lower electrode layer, 4-upper fixing substrate, 5-lower fixing substrate, 6-upper encapsulation layer, 7-lower encapsulation layer, 8-clamp, 9-hollow rivet. Detailed Implementation

[0025] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0026] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0027] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0028] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0029] In addition, the term "multiple" should mean two or more.

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] like Figure 1 As shown, this application provides a flexible thin-film sensor, including an encapsulation layer, a fixing substrate, an electrode layer, and a sensing unit 1, wherein: the sensing unit 1 is a PVDF thin film with a thickness of 8-12 μm; the electrode layer includes an upper electrode layer 2 and a lower electrode layer 3, the upper electrode layer 2 being disposed above the PVDF thin film and the lower electrode layer 3 being disposed below the PVDF thin film, both the upper electrode layer 2 and the lower electrode layer 3 being multilayer stacked structures fabricated using a magnetron sputtering process based on the PVDF thin film; the fixing substrate includes an upper fixing substrate 4 and a lower fixing substrate 5, the upper fixing substrate 4 being fixedly assembled with the upper electrode layer 2, and the lower fixing substrate 5 being fixedly assembled with the lower electrode layer 3; the encapsulation layer includes an upper encapsulation layer 6 and a lower encapsulation layer 7, the upper encapsulation layer 6 being fixedly connected to the upper fixing substrate 4 by bolts, and the lower encapsulation layer 7 being fixedly connected to the lower fixing substrate 5 by bolts.

[0032] Specifically, the flexible thin-film sensor provided in this application embodiment is mainly used for measuring the momentum characteristics of dust, such as... Figure 2As shown, the measurement principle is as follows: when space dust impacts the sensor, the pressure applied to the surface of the sensitive unit 1 causes a slight deformation of the PVDF film, resulting in a change in its internal charge distribution. As a piezoelectric polymer, PVDF will produce a change in charge distribution when subjected to pressure. These changes can be collected and processed by an external signal acquisition system connected to the electrode leads, and then monitored and displayed by an oscilloscope. The signal acquisition system can be converted into an easily detectable voltage signal by setting a specific charge amplification circuit. The intensity of the voltage signal is proportional to the impact force and momentum of the space dust. Therefore, the momentum of the space dust can be indirectly detected by measuring the voltage signal.

[0033] More specifically, in this embodiment, the sensing element 1 is a PVDF thin film, serving as the core response layer. The PVDF thin film undergoes specific polarization treatment, resulting in strong anti-interference capability and higher sensitivity of the sensor. The electrode layer includes an upper electrode layer 2 and a lower electrode layer 3, formed using a magnetron sputtering process with the PVDF thin film as the substrate, to enhance the detection capability of space dust and extract charge signals. The fixing substrate includes an upper fixing substrate 4 and a lower fixing substrate 5, used to fix the electrode layer and protect the sensing element 1. The encapsulation layer includes an upper encapsulation layer 6 and a lower encapsulation layer 7, to reduce external noise interference and improve wear resistance.

[0034] Furthermore, the encapsulation layer is made of aluminum alloy. Aluminum alloy is lightweight and has high mechanical strength, which can improve the overall anti-interference capability of the sensor; the thickness of the upper encapsulation layer 6 and the lower encapsulation layer 7 is preferably 15mm.

[0035] Furthermore, the substrate is made of glass. Glass substrates have high chemical stability and can resist the effects of radiation, gases, and other chemicals in the space environment; this protects the sensor components from chemical corrosion or damage. The smooth surface of the glass substrate, with its high-quality surface treatment, helps maintain the flatness and cleanliness of the sensor surface, thereby improving the accuracy and sensitivity of detecting space dust.

[0036] Furthermore, both the upper electrode layer 2 and the lower electrode layer 3 are composed of stacked Au and Cr layers, wherein: the Cr layer is sputtered on a PVDF thin film substrate and the thickness of the Cr layer is 5-6 nm; the Au layer is sputtered on the Cr layer and the thickness of the Au layer is 50-60 nm.

[0037] Specifically, in this embodiment, the electrode layer is mainly a stacked combination of Au / Cr layers, wherein the Au and Cr layers are the same size, preferably 5cm × 5cm. This results in a large overall receiving area for the electrode layer, enabling the detection of a wider range of spatial dust and firmly fixing the polarized PVDF film. The sputtering thickness of the Cr layer is preferably 5nm, and the sputtering thickness of the Au layer is preferably 50nm. Cr, as the bottom layer of Au, enhances the adhesion between the Au layer and the PVDF intermediate layer, preventing the metal layer from peeling or falling off. The Au layer protects the Cr layer from oxidation or corrosion, maintaining the integrity and stability of the coating, while also exhibiting good corrosion resistance, protecting the sensor from damage by the external environment. This metal electrode layer composed of Au / Cr, serving as a sensing transition layer, not only protects the PVDF film but also better transmits electrical signals to it, resulting in higher sensor sensitivity.

[0038] More specifically, the PVDF thin film with sputtered upper and lower electrode layers 3 is etched into a suitable shape using a nanosecond laser, ensuring that the length direction of the sensor aligns with the stretching direction of the PVDF thin film. During the etching process, numerous metal burrs can easily remain on the edges of the metal electrodes, potentially causing short circuits in the thickness direction of the PVDF piezoelectric thin film, thus affecting the normal operation of the subsequently fabricated sensor. Therefore, when etching the PVDF thin film, edge smoothing treatment is necessary. Acetone and alcohol are used as etchants to perform a non-metallization treatment on the edges of the PVDF thin film, i.e., etching away any edge electrode burrs that might connect the edges. Finally, a multimeter is used to check for short circuits. This treatment prevents short circuits in the thickness direction, ensuring the separation of the two surface electrodes.

[0039] Furthermore, such as Figure 3 As shown, the PVDF film is prepared by the following steps: Step 1: Dissolve PVDF in a quantitative N-methylpyrrolidone solution, preferably with a PVDF concentration of 10% in the N-methylpyrrolidone solution; Step 2: Apply the mixture to the surface of a silicon wafer by magnetic stirring and spin coating, with the rotation speed set at 300-500 rpm to achieve a thin coating thickness of 26-28 μm; Step 3: Remove residual bubbles using a vacuum degassing process to ensure the stability and reliability of the film quality; Step 4: Evaporate the N-methylpyrrolidone solution by heating at 60°C for 30 minutes to obtain the PVDF film; Step 5: Perform high-pressure thermal polarization treatment on the PVDF film using dimethyl silicone oil as the insulating medium.

[0040] Specifically, for PVDF films, a stretching process is generally used to obtain a higher content of the piezoelectric β phase. However, at this stage, the dipoles in the film are randomly arranged and macroscopically inactive, requiring artificial polarization treatment. By applying a high voltage, the dipoles in the film can be ordered along the direction of the external electric field. When the electric field is removed, some dipole orientations disappear instantaneously, while others remain, which is called the remanent polarization intensity, directly reflecting the piezoelectricity of the PVDF film.

[0041] More specifically, in the embodiments of this application, the PVDP thin film is treated using a high-voltage thermal polarization method, such as... Figure 4 As shown, the movement of molecular chains, ions, and space charges during thermal polarization causes the thin film surface to bend and deform, affecting the stable polarization of the sensitive area. Therefore, a certain pressure needs to be applied to the sample during the polarization process. It is preferable to use H201# type dimethyl silicone oil as the insulating medium. Dimethyl silicone oil has excellent insulation properties, which can prevent arcing at the electrode edge and also allows for the application of higher voltages.

[0042] Furthermore, lead wires are provided on the electrode layer, and the lead wires are fixed and led out using clamps 8 and hollow rivets 9.

[0043] Specifically, such as Figure 6 As shown, the PVDF film itself is thin and flexible, and its surface electrodes are thin, so conventional welding methods cannot be used to lead out its electrodes. In order to ensure a good connection between the led-out wires and the film, the embodiments of this application preferably use hollow rivets 9 and crimp terminals for through connection, leading out the upper and lower electrode layers of the PVDF film in the same direction and on the same plane, maximizing the protection of the charge signal from interference when it is transmitted to the preamplifier circuit, and using clamps 8 for fixation. The clamps are thin and easy to encapsulate and shield at the junction of the wires and electrode layers, which can prevent interference from external signals.

[0044] More specifically, the outgoing wires are connected to the subsequent signal acquisition system, which mainly includes a signal conditioning circuit, a signal processing circuit, and a signal transmission circuit. The signal conditioning circuit consists of a charge amplification and low-pass filtering circuit, which can achieve signal conditioning; the signal processing circuit includes a power supply circuit, a microprocessor control circuit, and a circuit control program design; the signal transmission circuit uses wired transmission to transmit data to the display terminal; finally, the signal is visualized through signal display software.

[0045] Furthermore, before PVDF film assembly, it is cleaned with alcohol and deionized water, followed by plasma treatment. Pre-treatment is required before PVDF film assembly, starting with cleaning with alcohol, then with deionized water, and finally plasma treatment. The vacuum level for plasma treatment is set to 30-50 Pa. This pressure level provides sufficient gas molecules to form plasma while maintaining the mean free path of the particles, ensuring effective interaction between the plasma and the material surface for cleaning. After 3 minutes at this vacuum level, the activity of the PVDF film surface is enhanced, improving the sensor's dust detection capability.

[0046] Furthermore, the measurable velocity range of high-speed dust particles in space is ≥1km / s, and the maximum measurable flux of space dust particles is 1000 particles / m³. 2 •s, sampling rate 300-350kHz.

[0047] Furthermore, the temperature tolerance range is -30℃ to +60℃, the stability is 10%, and the response time is <10℃.

[0048] Specifically, when space dust impacts a PVDF film, the dust momentum characteristics can be analyzed based on the conversion relationship between the particle's momentum and the voltage response of the PVDF film. For example... Figure 5 As shown, under simulated impact from 1g of TPU particles, the electrical signal of the flexible thin-film sensor provided in this embodiment responds quickly (response time < 1s), and the maximum change reaches 30V, demonstrating the sensor's characteristics of short response time and high sensitivity.

[0049] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A flexible thin film sensor, characterized by, The application discloses a sensor for measuring the momentum characteristics of high-speed dust in space, which comprises an encapsulating layer, a fixed substrate, an electrode layer and a sensitive unit. The sensitive unit is a PVDF film with a thickness of 8-12 microns. The electrode layer comprises an upper electrode layer and a lower electrode layer, wherein the upper electrode layer is arranged above the PVDF film, the lower electrode layer is arranged below the PVDF film, and the upper electrode layer and the lower electrode layer are both multilayer superimposed structures prepared by a magnetron sputtering process and taking the PVDF film as a substrate. The fixed substrate comprises an upper fixed substrate and a lower fixed substrate, wherein the upper fixed substrate is fixedly assembled with the upper electrode layer, and the lower fixed substrate is fixedly assembled with the lower electrode layer. The encapsulating layer comprises an upper encapsulating layer and a lower encapsulating layer, wherein the upper encapsulating layer is fixedly connected with the upper fixed substrate through bolts, and the lower encapsulating layer is fixedly connected with the lower fixed substrate through bolts. The material of the encapsulating layer is an aluminum alloy. The material of the fixed substrate is glass. The upper electrode layer and the lower electrode layer are both composed of an Au layer and a Cr layer. The Cr layer is sputtered on the PVDF film, and the thickness of the Cr layer is 5-6 nm. The Au layer is sputtered on the Cr layer, and the thickness of the Au layer is 50-60 nm. The electrode layer is provided with lead-out wires which are fixed by means of a chuck and a hollow rivet. The lead-out wires are connected with a subsequent signal acquisition system, and the signal acquisition system comprises a signal conditioning circuit, a signal processing circuit and a signal transmission circuit. The signal conditioning circuit is composed of a charge amplifier and a low-pass filter circuit and can realize signal conditioning.

2. The flexible thin film sensor of claim 1, wherein, The signal processing circuit is a power supply circuit, a microprocessor control circuit and a circuit control program design. The signal transmission circuit adopts wired transmission to transmit data to a display end. The signal visualization display is realized through signal display software. When space dust hits the sensor, the pressure applied to the surface of the sensitive unit causes the PVDF film to deform slightly, resulting in changes in the internal charge distribution. The PVDF film is prepared by the following steps: Step 1: dissolving PVDF in an N-methyl pyrrolidone solution; 3. The flexible thin film sensor of claim 2, wherein, Step 2: mixing the solution by magnetic stirring and spin coating to coat the solution onto the surface of a silicon wafer; 4. The flexible thin film sensor of claim 3, wherein, The measurable space high-speed dust velocity range is ≥1 km / s, and the maximum flux of the measurable space dust is 1000 / m 2 · s, sampling rate is 300-350 kHz.

5. The flexible thin film sensor of claim 4, wherein, Step 3: removing residual bubbles by vacuum degassing process; Step 4: evaporating the N-methyl pyrrolidone solution by heating to obtain a PVDF film; Step 5: using dimethyl silicone oil as an insulating medium to perform high-voltage thermal polarization treatment on the PVDF film by a thermal polarization method. Before the PVDF film is assembled, it is cleaned by alcohol and deionized water and then subjected to plasma treatment. The temperature tolerance range is -30-+60 DEG C, the stability is 10%, and the response time is less than 1 s.

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