Self-powered fluid sensor based on tribo-voltaic effect, method of manufacture and applications

Abstract

The application belongs to the field of micro-nano sensing, and particularly relates to a self-driven fluid sensor based on a frictional volt effect, a preparation method and application. The probe of the sensor is composed of a substrate, a working electrode and a reference electrode. The reference electrode comprises a conductive layer, and the working electrode comprises a conductive layer and a two-dimensional semiconductor layer. The sensor utilizes the liquid-solid interface frictional volt effect generated when the two-dimensional semiconductor material contacts with a fluid, and combines the Fermi level difference between the metal electrode and the nano film to construct a strong built-in electric field. The mechanical energy generated when the fluid flows is spontaneously converted into an electric signal highly related to the flow rate for output, so that high-sensitivity, non-destructive and self-driven in-situ monitoring of weak fluid pulses and constant flow states is realized, and the device does not need an external power supply for driving during operation. The application can overcome many defects of traditional fluid sensors, and has a wider application prospect.

Description

Technical Field

[0001] This invention belongs to the field of micro-nano sensing, specifically relating to a self-driven fluid sensor based on the tribovolt effect, its fabrication method, calibration method, and applications. Background Technology

[0002] Currently, fluid velocity monitoring mainly relies on various commercial fluid sensors. These sensors generally suffer from drawbacks such as reliance on complex mechanical or electronic structures, large size, rigid structure, need for external power supply, and susceptibility to interfering with the original weak flow field. In fields such as biomedicine and implantable medical devices, there is a widespread need to detect weak fluid flows within small cavities; however, existing fluid sensors cannot meet the fluid detection requirements in such scenarios. Existing flow velocity sensing devices still have significant shortcomings in practical applications, such as difficulty in achieving seamless integration with flexible pipe spaces, slow response to transient fluids, and lack of independent operation capability in confined or passive environments.

[0003] Therefore, there is an urgent need to design a new type of self-driven fluid sensing device that can be freed from the constraints of external power supply, has a flexible structure, is suitable for miniaturization, and can achieve in-situ and rapid monitoring, so as to meet the high-precision detection needs of micro or macro fluids in different fields. Summary of the Invention

[0004] To address the problem that existing fluid sensors are generally unsuitable for detecting the flow rate of minute fluids in confined and complex environments, this invention provides a self-driven fluid sensor based on the triboelectric effect, along with its fabrication method, calibration method, and applications.

[0005] This invention is achieved using the following technical solution: A self-driven fluid sensor based on the tribovolt effect includes a probe and a signal processing module. The probe includes an insulating substrate and at least one pair of reference electrodes and a working electrode attached to the substrate and spaced apart. The reference electrode includes a conductive layer; the working electrode includes a conductive layer and a two-dimensional semiconductor layer from bottom to top. The signal processing module is electrically connected to the conductive layers in the reference electrode and the working electrode, respectively.

[0006] When the fluid medium under test flows along the line connecting the reference electrode and the working electrode on the substrate surface, a liquid-solid interface triboelectric voltage effect is generated between the fluid medium and the two-dimensional semiconductor layer on the working electrode surface. The signal processing module acquires the electrical signal generated between the conductive layers of the reference electrode and the working electrode; and according to the pre-calibrated "electrical signal-flow velocity" mapping corresponding to the current fluid medium, converts the measured electrical signal into a fluid flow velocity measurement result; or further generates a flow rate measurement result based on the flow velocity.

[0007] As a further improvement of the present invention, the substrate adopts a sheet-like structure or a tubular structure. On the sheet-like substrate, the reference electrode and the working electrode are distributed in a lattice pattern. On the tubular substrate, the reference electrode and the working electrode are distributed axially in a strip-like, ring-like, cross-shaped, or spiral pattern at intervals.

[0008] As a further improvement of the present invention, the probe includes a reference electrode and multiple working electrodes on a sheet-like substrate. The working electrodes are arranged in a ring with intervals, and the reference electrode is located in the center of the working electrodes. The signal processing module includes multiple signal acquisition channels, each of which is electrically connected to the conductive layer in the reference electrode and one of the working electrodes, and is used to measure the flow velocity of the fluid medium in the direction of the line connecting the two electrodes.

[0009] The signal processing module measures the flow velocity of the fluid medium flowing through the probe in different directions based on the electrical signals acquired by each signal acquisition channel.

[0010] As a further improvement of the present invention, the probe in the tubular substrate includes multiple pairs of reference electrodes and working electrodes spaced apart along the axial direction of the substrate. The signal processing module includes multiple signal acquisition channels, each of which is electrically connected to the conductive layer in an adjacent pair of reference electrodes and working electrodes; and is used to measure the flow velocity of the fluid medium in the direction of the line connecting the two electrodes.

[0011] The signal processing module measures the flow velocity of the fluid medium flowing through the probe in each section of the tubular substrate based on the electrical signals acquired by each signal acquisition channel.

[0012] As a further improvement of the present invention, the reference electrode and the working electrode are disposed on either side or both sides of the substrate.

[0013] As a further improvement of the present invention, in the self-driven fluid sensor based on the triboelectric effect, the substrate is made of a rigid or flexible material. Preferably, the substrate can be made of alumina, monocrystalline silicon, polycrystalline silicon, PDMS, silicone, polyurethane, polyvinyl chloride, or polyethylene.

[0014] Preferably, the conductive layer can be made of gold, platinum, silver, copper or a transparent conductive oxide.

[0015] Preferably, the two-dimensional semiconductor layer is prepared using ML-MoS2, graphene, tungsten disulfide, molybdenum diselenide, or black phosphorus.

[0016] Preferably, conductive silver paste is further provided between the conductive layers of the reference electrode and the working electrode in the probe and the substrate; the conductive silver paste is electrically connected to one end of the enameled wire, and the other end of the enameled wire is electrically connected to the signal processing module.

[0017] As a further improvement of the present invention, in the signal processing module, the electrical signal used to generate the measurement result includes the original current signal or voltage signal output between the two conductive layers, or the signal generated after the original signal has been processed by any one or more signal processing means including signal amplification and filtering.

[0018] This invention also includes a method for fabricating a self-driven fluid sensor based on the triboelectric effect as described above, comprising: S1: Prepare the base material.

[0019] S2: Apply conductive silver paste to the distribution area of ​​the preset reference electrode and working electrode on the substrate, and use the conductive silver paste to fix one end of the enameled wire.

[0020] S3: A conductive layer is deposited in the distribution area of ​​the reference electrode and the working electrode using high-vacuum electron beam evaporation coating technology.

[0021] S4: A two-dimensional semiconductor material is coated on top of the conductive layer in the distribution area of ​​the working electrode to obtain a two-dimensional semiconductor layer.

[0022] S5: After electrically connecting the other end of the enameled wire to the signal processing module with the pre-installed driver, the desired self-driven fluid sensor is obtained.

[0023] The pre-installed driver in the signal processing module is used to acquire the electrical signals generated by the conductive layers of the reference electrode and working electrode in the probe under the excitation of the fluid medium under test; and according to the pre-calibrated "electrical signal-flow velocity" mapping corresponding to the current fluid medium, the measured electrical signal is converted into the measurement result of the fluid flow velocity.

[0024] The present invention also includes a calibration method for a self-driven fluid sensor, used to calibrate the built-in "electrical signal-flow velocity" mapping in the signal processing module of a self-driven fluid sensor based on the aforementioned triboelectric effect. The calibration method includes the following steps: An existing flow velocity sensor and a probe from a self-driven fluid sensor based on the tribovolt effect were installed in the same experimental chamber within the fluid circulation system.

[0025] Introduce any target medium into the fluid circulation system and drive the target medium to circulate within the fluid circulation system according to a preset initial flow rate.

[0026] Synchronous recording of the electrical signal ES output by the probe i and the flow velocity value CV measured by the flow velocity sensor i And obtain a data point (ES) i CV i ).

[0027] The flow velocity of the target medium in the fluid circulation system is dynamically adjusted in steps until the final flow velocity value is reached, thereby obtaining a series of data points; (ES1, CV1) ~ (ES n CV n ), where n represents the number of data points.

[0028] Generate an "electrical signal-flow velocity" mapping for the current target medium based on the obtained set of data points.

[0029] By changing the type of target medium in the fluid circulation system and repeating the same test process, the "electrical signal-flow velocity" mapping corresponding to each target medium can be obtained.

[0030] The present invention also includes a self-driven fluid sensor based on the tribovolt effect, as described above, for use in industrial fluid monitoring or implantable medical devices.

[0031] The technical solution provided by this invention has the following beneficial effects: This invention provides a novel self-driven fluid sensor based on the triboelectric effect. The sensor probe consists of three parts: a substrate, a working electrode, and a reference electrode. The working electrode utilizes the triboelectric effect at the liquid-solid interface generated when a two-dimensional semiconductor material comes into contact with a fluid, combined with the Fermi level difference between the metal electrode and the nanofilm to construct a strong built-in electric field. This structure breaks the dependence of traditional sensors on an external power source; as fluid flows through it, it spontaneously and directionally outputs an electrical signal highly correlated with the flow velocity, thereby achieving highly sensitive, non-destructive, and self-driven in-situ monitoring of weak fluid pulses and constant flow states.

[0032] This new sensor no longer relies on the complex mechanical structure of traditional fluid sensors. It can be applied to various application scenarios of traditional fluid sensors, and can be miniaturized and manufactured in various forms. It can even be fabricated using flexible semiconductor technology to achieve seamless bonding with tiny curved surfaces. It can also support integration into human implantation or microfluidic systems, making its application scenarios very wide.

[0033] This new sensor can achieve passive drive, has extremely fast transient response, and can accurately identify and output fluid signals. The product has a simple structure, small size, and extremely high spatial adaptability. It can be used to measure a variety of different types of fluids (including various high-temperature or corrosive fluids) in extreme environments. Attached Figure Description

[0034] Figure 1 This is a simplified functional model of the self-driven fluid sensor based on the triboelectric effect provided in Embodiment 1 of the present invention.

[0035] Figure 2This is a schematic diagram of the sheet-like probe provided in Embodiment 1 of the present invention.

[0036] Figure 3 This is a schematic diagram of the tubular structure probe provided in Embodiment 1 of the present invention.

[0037] Figure 4 This is a schematic diagram of the self-driven fluid sensor based on the triboelectric effect provided in Embodiment 1 of the present invention.

[0038] Figure 5 This is a schematic diagram of the structure of the probe for multi-directional flow velocity measurement provided in Embodiment 1 of the present invention.

[0039] Figure 6 This is a schematic diagram of the probe for segmented flow velocity measurement provided in Embodiment 1 of the present invention.

[0040] Figure 7 This is a schematic cross-sectional view of the working electrode and reference electrode containing conductive silver paste.

[0041] Figure 8 This is a flowchart of the steps involved in the fabrication method of the self-driven fluid sensor based on the triboelectric effect provided in Embodiment 2 of the present invention.

[0042] Figure 9 This is a schematic diagram of the layering of the working electrode in the probe prepared according to Embodiment 2 of the present invention.

[0043] Figure 10 This is a schematic diagram of the layering of the reference electrode in the probe prepared according to Embodiment 2 of the present invention.

[0044] Figure 11 This is a flowchart of the calibration method for the "electrical signal-flow velocity" mapping provided in Embodiment 2 of the present invention. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0046] Example 1 To address the limitations of existing fluid sensors, such as the difficulty in miniaturization, the need for external power, and the inability to achieve non-contact detection in confined or human-occupied environments, this embodiment provides a self-driven fluid sensor based on the triboelectric effect. Figure 1 As shown, it includes a probe and a signal processing module. The probe includes a substrate and at least one pair of reference electrodes and working electrodes attached to the substrate and spaced apart. The reference electrodes include a conductive layer; the working electrodes include a conductive layer and a two-dimensional semiconductor layer from bottom to top.

[0047] In practical applications, the substrate primarily uses insulating materials with strong weather resistance. Depending on the application scenario, the substrate can be made of rigid materials to ensure the structural stability and reliability of the probe. Examples include monocrystalline silicon, polycrystalline silicon, alumina, and other substrate materials commonly used in semiconductor processes, including composite materials. In other embodiments, the substrate can also use various flexible materials, allowing the probe to be shaped into any form or to meet the requirements for product flexibility in certain implantation scenarios. For example, the substrate can use silicone polymers including PDMS (commonly known as silicone), polyurethane (PU), polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), and various substrate materials commonly used in flexible semiconductor processes.

[0048] In practical applications, the probe portion of the self-driven fluid sensor product in this embodiment can be adopted in any form according to the needs of the actual application scenario. Typically, it can adopt a sheet-like structure or a tubular structure. The sheet-like probe can detect the flow rate of the fluid flowing over its surface, while the tubular probe can detect the flow rate of the fluid flowing inside or outside its pipe.

[0049] To achieve different probe shapes, such as Figure 2 and Figure 3 As shown, the substrate in this embodiment adopts a sheet-like structure or a tubular structure. For substrates with different structures, the reference electrode and working electrode in this embodiment can also exhibit different morphologies. For example, on a sheet-like substrate, the reference electrode and working electrode are distributed in a lattice pattern; wherein, the reference electrode and working electrode may include only one pair, or multiple pairs, and be distributed in a complex patterned manner. Correspondingly, on a tubular substrate, the reference electrode and working electrode can be distributed along its axial direction in a strip-like, ring-like, cross-shaped, or spiral pattern.

[0050] In this embodiment, the two electrodes on the substrate adopt an asymmetrical structure. The electrode containing only a conductive layer serves as the reference electrode, while the electrode covered by a two-dimensional semiconductor layer serves as the working electrode. Together, they constitute a dual-electrode microsensor. When the fluid medium to be measured flows on the substrate surface along the line connecting the reference electrode and the working electrode, a liquid-solid interface triboelectric voltage effect is generated between the fluid medium and the two-dimensional semiconductor layer on the surface of the working electrode, resulting in an electrical signal between the asymmetrical dual electrodes.

[0051] Specifically, during the fluid flow, friction occurs between the fluid and the two-dimensional semiconductor layer on the surface of the working electrode. Due to the significant Fermi level difference between the work function of the conductive layer and the two-dimensional semiconductor layer, a substantial built-in electric field is formed at the interface. As the fluid continues to rub against the working electrode, the dangling bonds at the interface interact with the fluid molecules, exciting a large number of electron-hole pairs. The built-in electric field then causes charges to flow through the external circuit between the working electrode and the reference electrode, directly converting the mechanical energy of the fluid flow into an electrical signal.

[0052] In practical applications, the electrical signal output between the working electrode and the reference electrode is mainly related to parameters such as the chemical composition of the fluid, the material of the fluid, and the material and size of the two-dimensional semiconductor layer. In a specific product, the shape, size, and material of the working electrode and the reference electrode in the probe remain fixed; therefore, when using this probe to detect a specified type of fluid in any scenario, the strength of the electrical signal output by the probe will only be related to the flow rate of the fluid.

[0053] Based on this, this embodiment electrically connects the signal processing module to the conductive layers in the reference electrode and the working electrode, respectively. The signal processing module has two functions: first, to acquire the electrical signals generated by the two electrodes during fluid detection; and second, to convert the acquired electrical signals into fluid velocity detection results. Therefore, in the self-driven fluid sensor based on the triboelectric effect provided in this embodiment, in order to achieve fluid detection, the signal processing module acquires the electrical signals generated between the conductive layers of the reference electrode and the working electrode; and according to the pre-calibrated "electrical signal-velocity" mapping corresponding to the current fluid medium, converts the measured electrical signals into fluid velocity measurement results. Of course, in practical applications, based on the known cross-sectional area of ​​the fluid at the detection location and the measured fluid velocity, the fluid velocity can be further calculated.

[0054] In the signal processing module, the electrical signal used to generate the fluid velocity measurement result based on the "electrical signal-flow velocity" mapping can be the original voltage or current signal output from the probe, or it can be the electrical signal obtained after filtering, amplification, Fourier transform, or any other signal processing. The only requirement is that this electrical signal has a stronger correlation with the flow velocity of the fluid being detected, so that the sensor's detection accuracy meets the requirements.

[0055] In practical applications, the probe section requires only a minimum of one set of working electrodes and a reference electrode to measure the flow velocity of a uniform fluid flowing between them. To further highlight the principle and performance advantages of the self-driven fluid sensor provided in this embodiment, the following... Figure 1 Using a probe model consisting of only one reference electrode and one working electrode as an example, the working principle of this self-driven fluid sensor will be described in detail. Figure 4 for Figure 1 The diagram shows the principle of the triboelectric voltage effect at the liquid-solid interface generated by the self-driven fluid sensor under fluid excitation. Figure 4 In the middle, E C It is the conduction band of the semiconductor, EFS is the Fermi level of the semiconductor, E V It is the valence band of semiconductors, E L It treats water as the Fermi level of a liquid semiconductor, E FM It is the Fermi level of a metal, while Evac is the vacuum level. (Combined) Figure 4 The principle by which the self-driven fluid sensor in this embodiment achieves flow velocity sensing is as follows: (I) Construction of the Built-in Electric Field at the Interface: In the working electrode, the inner layer is a conductive layer, the material of which generally has a high work function, while the outer layer is a two-dimensional semiconductor layer exhibiting N-type semiconductor characteristics. When the two are in close contact, in order to achieve thermodynamic equilibrium, electrons will spontaneously transfer from the two-dimensional semiconductor layer to the conductive layer until their Fermi levels are aligned. This charge transfer process causes band bending at the interface, thereby constructing a Schottky junction and a significant strong built-in electric field.

[0056] (ii) Separation of electron-hole pairs: When the fluid flows through the probe surface, it continuously undergoes dynamic liquid-solid interface friction with the surface of the extremely thin two-dimensional semiconductor layer in the working electrode. This high-frequency collision and friction breaks the thermodynamic equilibrium of the interface, causing the fluid molecules to interact strongly with the dangling bonds on the surface of the two-dimensional semiconductor layer. This directly converts the mechanical kinetic energy of the fluid into the transition energy of electrons, which excites the electrons in the two-dimensional semiconductor layer, thereby generating a large number of electron-hole pairs at the interface.

[0057] (III) Directional Movement of Charge: Under the influence of the strong built-in electric field at the interface, the newly generated electrons and holes due to friction are rapidly and efficiently separated in opposite directions. Simultaneously, because the sensor probe employs a spatially asymmetric dual-electrode layout design—one end being the working electrode that excites a large number of electron-hole pairs, and the other end being a bare reference electrode that does not undergo semiconductor excitation—a significant potential difference is generated macroscopically between the two. Driven by this asymmetric potential difference, the separated free charges are forced to flow directionally between the working electrode and the reference electrode through an external circuit, thereby maintaining charge balance.

[0058] Based on the above process, the mechanical energy of fluid flow is directly and continuously converted into observable electrical signal output, realizing self-driven precise flow velocity sensing.

[0059] In practical applications, to achieve the aforementioned triboelectric effect at the liquid-solid interface on the working electrode, the conductive layer can be made of gold, platinum, silver, copper, or a transparent conductive oxide; to achieve a higher work function, gold is preferred. Correspondingly, the two-dimensional semiconductor layer can be made of various two-dimensional nanomaterials capable of forming the aforementioned Schottky junction with the conductive layer, such as monolayer molybdenum disulfide (ML-MoS2), graphene, tungsten disulfide, molybdenum diselenide, or black phosphorus, etc. In practical applications, ML-MoS2 is preferred.

[0060] Based on the above introduction, such as Figure 1 The diagram illustrates the basic architecture of a self-driven fluid sensor capable of flow velocity sensing. In practical applications, this embodiment further provides various sensor products applicable to diverse scenarios. Preferably, the first type is a multi-directional flow velocity sensor, used to precisely measure the flow velocity of fluid flowing through a single point in different directions, and can be widely used in the field of microfluidics. Specifically, the sensor substrate is sheet-like, and the sheet-like substrate is preferably made of a rigid material. Figure 5 As shown, on a sheet-like substrate, the probe includes a reference electrode and multiple working electrodes, with the working electrodes arranged in a ring at intervals. The reference electrode is located in the center of the working electrodes. The reference electrode and working electrodes can be placed on either side of the substrate, or simultaneously on both the upper and lower surfaces, and either side can be selected for detection according to actual needs.

[0061] Correspondingly, the signal processing module includes multiple signal acquisition channels. Each signal acquisition channel is electrically connected to a reference electrode and a conductive layer in one of the working electrodes, and is used to measure the flow velocity of the fluid medium in the direction of the line connecting the two. Therefore, in this embodiment, the signal processing module can measure the flow velocity of the fluid medium flowing through the probe in different directions based on the electrical signals acquired by each signal acquisition channel. In practical applications, the sensor can operate in different modes. For example, the signal processing module can time-division multiplex the signal acquisition channels in different directions to measure the fluid flow velocity in different directions sequentially; or it can simultaneously acquire the electrical signals on all channels to achieve synchronous measurement of the fluid flow velocity in different directions.

[0062] In the second improved solution provided in this embodiment, the sensor substrate is made of a tubular material, such as... Figure 6As shown, within a tubular substrate, the probe includes multiple pairs of reference electrodes spaced apart along the substrate's axial direction and multiple working electrodes. The signal processing module includes multiple signal acquisition channels, each electrically connected to a conductive layer in an adjacent pair of reference and working electrodes; and is used to measure the flow velocity of the fluid medium along the line connecting them. In this type of sensor, the signal processing module can measure the flow velocity of the fluid medium flowing through the probe in different sections of the tubular substrate based on the electrical signals acquired by each signal acquisition channel. This sensor is more suitable for detecting flow velocities or fluid pulses in different sections of pipes or similar elongated spaces.

[0063] In practical applications, a tubular probe can be arranged along the extension direction of the space to be measured. The reference electrode and working electrode on the substrate can be placed on the inner wall of the tubular substrate; in this case, the outer diameter of the probe matches the inner diameter of the pipe to be measured, allowing the tubular substrate to fit snugly against the inner wall of the pipe, thus enabling the measurement of the flow velocity of the fluid flowing through the pipe. Alternatively, the reference electrode and working electrode can be placed on the outer wall of the tubular substrate; in this case, the outer diameter of the probe should be smaller than the inner diameter of the pipe to be measured, placing the probe in the center of the pipe, allowing the fluid to flow along both the inner and outer sides of the tubular substrate within the probe, avoiding any obstruction to the flow of fluid within the pipe; and enabling the measurement of the flow velocity of the fluid flowing through the pipe.

[0064] The self-driven fluid sensor of this embodiment can be used for in-situ flow rate monitoring in clinical intravenous infusion or minimally invasive environments. For example, in human blood vessels or similar implantable applications, the aforementioned tubular substrate solution can be used. In this case, the substrate material is preferably a flexible material, such as a flexible polyurethane catheter similar to a medical indwelling needle. The reference electrode and working electrode are respectively disposed on the outer walls of the catheter at both ends. After implantation into the human body, non-invasive detection can be achieved. The self-driven fluid sensor of this embodiment can also be used for flow rate sensing of laboratory microfluidics or chemical reagents. For example, by replacing the substrate with a flexible PDMS micro-silicone tubing or a rigid capillary glass tube, and placing the working electrode and reference electrode on the inner or outer wall of the tube, the resulting sensing component can be embedded in a microfluidic chip system.

[0065] To ensure reliable electrical signal transmission between the conductive layers of the probe's working and reference electrodes and the signal processing module, the signal processing module can be directly electrically connected to the conductive layers of the two electrodes using enameled wire or other types of conductors. Therefore, in the probe of this embodiment, as... Figure 7 As shown, conductive silver paste is also provided between the conductive layer of the reference electrode and the working electrode and the substrate; the conductive silver paste is electrically connected to one end of the enameled wire, and the other end of the enameled wire is electrically connected to the signal processing module.

[0066] Example 2 Based on the technical solution provided in Example 1, this embodiment further provides a method for fabricating a self-driven fluid sensor based on the triboelectric effect as described in Example 1. Figure 8 As shown, the preparation method includes the following steps: S1: Prepare the base material.

[0067] In this embodiment, the substrate material can adopt a sheet-like or tubular structure according to the actual application scenario, and a specified flexible or rigid substrate material can be selected as needed; such as organosilicon polymers, polyurethane, polyvinyl chloride, polyethylene, polypropylene, monocrystalline silicon, polycrystalline silicon, alumina, aluminum nitride, etc.

[0068] For tubular substrates, pre-formed tubular components can be used, with reference electrodes and working electrodes formed on their surface. Alternatively, the reference and working electrodes can be patterned on the surface of a sheet material according to the distribution positions of the two types of electrodes, and then the sheet substrate can be rolled into the desired tubular shape.

[0069] S2: Apply conductive silver paste to the pre-defined distribution areas of the reference and working electrodes on the substrate, and use the conductive silver paste to fix one end of the enameled wire. The other end of the enameled wire connected to the two areas is reserved as the signal output terminal of the probe.

[0070] S3: A conductive layer is deposited in the distribution area of ​​the reference electrode and the working electrode using high-vacuum electron beam evaporation coating technology.

[0071] In this embodiment, the conductive layers in the reference electrode and the working electrode can be made of the same material or different materials. In practical applications, to improve the sensitivity of the probe and simplify the process, the conductive layers in both the working electrode and the reference electrode are usually made of Au thin film. When depositing the Au thin film, a mask can be pre-set so that Au is deposited only in the area where the conductive silver paste layer has already formed. The deposited Au thin film constitutes the two base electrodes.

[0072] S4: A two-dimensional semiconductor material is coated on top of the conductive layer in the distribution area of ​​the working electrode to obtain a two-dimensional semiconductor layer.

[0073] In this embodiment, if one of the two base electrodes composed of an Au thin film is covered with an ML-MoS2 or other two-dimensional semiconductor material, that electrode serves as the working electrode, while the other electrode, with its conductive layer directly exposed, serves as the reference electrode; the two electrodes form an asymmetric electrode structure on the substrate surface. The unfolded structure of the two electrodes on the tubular substrate is shown below. Figure 9 and Figure 10 As shown.

[0074] S5: After electrically connecting the other end of the enameled wire to the signal processing module with the pre-installed driver, the desired self-driven fluid sensor is obtained.

[0075] The pre-installed driver in the signal processing module is used to acquire the electrical signals generated by the conductive layers of the reference electrode and working electrode in the probe under the excitation of the fluid medium under test; and according to the pre-calibrated "electrical signal-flow velocity" mapping corresponding to the current fluid medium, the measured electrical signal is converted into the measurement result of the fluid flow velocity.

[0076] In this embodiment, the signal processing module connected to the same probe can have a built-in "electrical signal-flow velocity" mapping corresponding to different fluid media. During actual measurement, the technician can pre-specify the type of fluid medium being measured according to the measurement scenario, and the signal processing module will complete the analog-to-digital conversion of the measurement signal according to the specified "electrical signal-flow velocity" mapping corresponding to the fluid medium.

[0077] In practical applications, the "electrical signal-flow velocity" mapping of the same type of probe under different fluid media measurement environments can be pre-calibrated in the constructed test environment. This embodiment also provides a calibration method for a self-driven fluid sensor, which is used to calibrate the "electrical signal-flow velocity" mapping built into the signal processing module of the self-driven fluid sensor based on the aforementioned triboelectric effect. Figure 11 As shown, the calibration method includes the following steps: 1. Install an existing flow velocity sensor and the probe of a self-driven fluid sensor based on the friction volt effect in the same experimental chamber of the fluid circulation system. In this embodiment, the flow velocity sensor should be any flow rate or velocity sensor other than those based on the friction volt effect, such as a vortex flow sensor, turbine flow meter, electromagnetic flow meter, etc. This flow velocity sensor serves as the reference for the self-driven fluid sensor to be calibrated, therefore it needs to meet the preset measurement accuracy requirements.

[0078] 2. Introduce any target medium into the fluid circulation system and drive it to circulate within the system at a preset initial flow rate. Simultaneously record the electrical signal ES output by the probe. i and the flow velocity value CV measured by the flow velocity sensor i And obtain a data point (ES) i CV i The flow velocity of the target medium within the fluid circulation system is dynamically adjusted in steps until the final flow velocity value is reached, thereby obtaining a series of data points; (ES1, CV1) ~ (ES... n CV n ), where n represents the number of data points.

[0079] Finally, an "electrical signal-flow velocity" mapping corresponding to the current target medium is generated based on the obtained data point set. In this embodiment, the "electrical signal-flow velocity" mapping can use a fitted mapping function or a lookup table. In practical applications, the signal processing module converts the measured electrical signal into the required flow velocity measurement result through function calculation or table lookup.

[0080] Third, change the type of target medium in the fluid circulation system and repeat the same test process to obtain the "electrical signal-flow velocity" mapping corresponding to each target medium.

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A self-driven fluid sensor based on the tribovolt effect, characterized in that, It includes a probe and a signal processing module; the probe includes an insulating substrate and at least a pair of reference electrodes and working electrodes attached to the substrate and spaced apart; the reference electrodes include a conductive layer; the working electrodes include a conductive layer and a two-dimensional semiconductor layer from bottom to top; the signal processing module is electrically connected to the conductive layers in the reference electrodes and the working electrodes, respectively. When the fluid medium under test flows on the substrate surface along the line connecting the reference electrode and the working electrode, a liquid-solid interface tribovolt effect is generated between the fluid medium and the two-dimensional semiconductor layer on the surface of the working electrode. The signal processing module acquires the electrical signal generated between the conductive layers of the reference electrode and the working electrode; and converts the measured electrical signal into a fluid velocity measurement result according to the pre-calibrated "electrical signal-flow velocity" mapping corresponding to the current fluid medium; or further generates a flow rate measurement result based on the flow velocity.

2. The self-driven fluid sensor based on the triboelectric effect as described in claim 1, characterized in that: The substrate adopts a sheet-like structure or a tubular structure; The reference electrode and the working electrode are distributed in a lattice pattern on a sheet-like substrate; On the tubular substrate, the reference electrode and the working electrode are distributed axially in a strip, ring, cross, or spiral pattern.

3. The self-driven fluid sensor based on the triboelectric effect as described in claim 2, characterized in that: On a sheet-like substrate, the probe includes a reference electrode and multiple working electrodes, with the working electrodes arranged in a ring at intervals, and the reference electrode located in the center of the working electrodes. The signal processing module includes multiple signal acquisition channels. Each signal acquisition channel is electrically connected to a reference electrode and a conductive layer in one of the working electrodes, and is used to measure the flow rate of the fluid medium in the direction of the connection between the two. The signal processing module measures the flow velocity of the fluid medium flowing through the probe in different directions based on the electrical signals acquired by each signal acquisition channel.

4. The self-driven fluid sensor based on the triboelectric effect as described in claim 2, characterized in that: In the tubular substrate, the probe includes multiple pairs of reference electrodes and working electrodes spaced apart along the substrate axis; The signal processing module includes multiple signal acquisition channels, each of which is electrically connected to the conductive layer in an adjacent pair of reference electrodes and working electrodes; and is used to measure the flow rate of the fluid medium in the direction of the line connecting the two electrodes. The signal processing module measures the flow velocity of the fluid medium flowing through the probe in each section of the tubular substrate based on the electrical signals acquired by each signal acquisition channel.

5. The self-driven fluid sensor based on the triboelectric effect as described in claim 2, characterized in that: The reference electrode and the working electrode are disposed on either side or both sides of the substrate.

6. The self-driven fluid sensor based on the triboelectric effect as described in claim 1, characterized in that: The substrate is made of rigid or flexible materials; And / or, the substrate is made of alumina, monocrystalline silicon, polycrystalline silicon, PDMS, silicone, polyurethane, polyvinyl chloride or polyethylene; And / or, the conductive layer is made of gold, platinum, silver, copper or a transparent conductive oxide; And / or, the two-dimensional semiconductor layer is prepared using ML-MoS2, graphene, tungsten disulfide, molybdenum diselenide or black phosphorus; And / or, conductive silver paste is provided between the conductive layers of the reference electrode and the working electrode in the probe and the substrate; the conductive silver paste is electrically connected to one end of the enameled wire, and the other end of the enameled wire is electrically connected to the signal processing module.

7. The self-driven fluid sensor based on the triboelectric effect as described in claim 1, characterized in that: In the signal processing module, the electrical signal used to generate the measurement result includes the original current signal or voltage signal output between the two conductive layers, or the signal generated after the original signal has been processed by any one or more signal processing methods, including signal amplification and filtering.

8. A method for fabricating a self-driven fluid sensor based on the triboelectric effect as described in any one of claims 1-7, characterized in that, It includes: S1: Prepare the base material; S2: Apply conductive silver paste to the distribution area of ​​the preset reference electrode and working electrode on the substrate, and use the conductive silver paste to fix one end of the enameled wire. S3: A conductive layer is deposited in the distribution area of ​​the reference electrode and the working electrode using high-vacuum electron beam evaporation coating technology; S4: A two-dimensional semiconductor material is coated on top of the conductive layer in the distribution area of ​​the working electrode to obtain a two-dimensional semiconductor layer; S5: After electrically connecting the other end of the enameled wire to the signal processing module with the pre-installed driver, the desired self-driven fluid sensor is obtained; The signal processing module is used to acquire the electrical signals generated by the conductive layers of the reference electrode and working electrode in the probe under the excitation of the fluid medium under test; and convert the measured electrical signals into the fluid flow rate measurement results according to the pre-calibrated "electrical signal-flow rate" mapping corresponding to the current fluid medium.

9. A calibration method for a self-driven fluid sensor, used to calibrate the built-in "electrical signal-flow velocity" mapping in the signal processing module of the self-driven fluid sensor based on the triboelectric effect as described in any one of claims 1-7; the calibration method includes the following steps: An existing flow velocity sensor and a probe from a self-driven fluid sensor based on the tribovolt effect are installed in the same experimental chamber within a fluid circulation system. Introduce any target medium into the fluid circulation system and drive the target medium to circulate within the fluid circulation system according to a preset initial flow rate. The electrical signal ES output by the probe is recorded synchronously. i and the flow velocity value CV measured by the flow velocity sensor. i And obtain a data point (ES) i CV i ); The flow velocity of the target medium in the fluid circulation system is dynamically adjusted in steps until the final flow velocity value is reached, thereby obtaining a series of data points; Generate an "electrical signal-flow velocity" mapping for the current target medium based on the obtained set of data points; By changing the type of target medium in the fluid circulation system and repeating the same test process, the "electrical signal-flow velocity" mapping corresponding to each target medium can be obtained.

10. The application of a self-driven fluid sensor based on the triboelectric effect as described in any one of claims 1-7 in industrial fluid monitoring or implantable medical devices.

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