CN103884465A - Pressure and differential pressure measuring device based on pore passage double electric layer effect - Google Patents

Abstract

The invention discloses a pressure and differential pressure measuring device based on the double electric layer effect of the hole. The inner wall of the pores of the porous membrane in the present invention is coated with a metal layer. When the electrolyte is driven by pressure to flow through the pores, the ions in the electrolyte will generate an electric double layer effect in the pores, and form a current in the closed circuit formed by the pores and the signal acquisition device. After the current or voltage signal in the circuit is collected, the value of pressure or pressure difference can be obtained through calculation. The device of the present invention has no mechanical rotating parts, is simple in structure, stable and reliable, does not need to provide external power supply equipment for driving, has no pollution and noise, and is very friendly to the environment; the present invention can be applied to fluids such as liquids and gases, and can even Contains solid suspended particles; the invention can realize measurement in different ranges according to different pore sizes and liquids containing different ions, with high sensitivity and large measurement range.

Description

A Pressure and Differential Pressure Measuring Device Based on Pore Electric Double Layer Effect

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technical field

The invention belongs to the detection field, and relates to a pressure and differential pressure measuring device based on the effect of the electrical double layer of the channel.

Background technique

Pressure and pressure difference are common parameters in industrial production practice. Their measurement and data collection are widely used in various equipment and devices, involving water conservancy and hydropower, production automation, aerospace, military industry, petrochemical, medical and many other industries. In addition, people can indirectly obtain physical parameters such as temperature, flow rate and liquid level through the measured pressure. The requirements for pressure and differential pressure measurement in different fluid electrolytes make the measurement methods different and have their own characteristics.

At present, the measurement principles of pressure sensors include piezoresistive, capacitive, piezoelectric, etc. The principles of these pressure measurements are different, and they are used in various fields according to their applicable conditions and measurement ranges. With the advancement of material technology and technology, the demand for industrial applications continues to develop, and it is required to improve the response speed and measurement accuracy of pressure measurement and reduce the volume of measurement devices. In particular, the size of devices and equipment made by micro-electromechanical systems (MEMS) and system-on-chip (System on Chip) technology is extremely small, and the measured space size is at the micro-nano level, which puts higher requirements on the measurement components; and because The very small size has higher requirements for measurement error and precision than the measurement of large size, and the data acquisition time is short, and the device requires intelligence, which makes some traditional pressure measurement methods inapplicable or not accurate enough. In addition, due to the limitations of the measurement principle, some traditional measurement methods are difficult to apply at the micro-nano scale, and some pressure measurement methods with mechanical rotating parts will greatly reduce their reliability and accuracy.

Contents of the invention

In order to overcome the shortcomings and deficiencies of the prior art, the present invention provides a pressure and differential pressure measuring device based on the effect of the electric double layer of the hole. the

The technical scheme provided by the invention is as follows:

A pressure and differential pressure measuring device consisting of a porous membrane, an elastic material surrounding the porous membrane, two pressure-sensitive bladders made of a flexible membrane, metal wires wrapped in insulating material, and a signal placed outside the pressure-sensitive bladders Acquisition device; wherein, the pore diameter of the porous membrane is micron-scale or nano-scale, the inner wall of the porous membrane is coated with a metal layer, and the metal layer is welded with metal wires, and the metal wires are led out of the pressure-sensitive airbag and the signal acquisition device Connected; there is a pressure-sensitive airbag on both sides of the porous membrane, and the porous membrane and the pressure-sensitive airbag are sealed by an elastic material surrounding the porous membrane; the two pressure-sensitive airbags contain electrolytes of different concentrations, and the electrolyte passes through The micro-nano channels of the porous membrane generate electrical signals due to the double-layer effect, and the electrical signals are transmitted to the signal acquisition device through metal wires; the signal acquisition device converts the electrical signals into pressure or differential pressure value output. the

The porous membrane is aluminum oxide nanoporous membrane, porous glass fiber or silicon oxide nanoporous membrane.

The method for coating the inner wall of the porous film with a metal layer comprises the following steps: firstly adopting the method of magnetron sputtering to make a metal layer with a nanometer thickness on one side of the porous film, and then soldering a metal layer wrapped with an insulating layer on the surface of the metal layer. The metal wire of the material, and then adopts the method of electrodeposition to plate a layer of metal halide with a thickness of nanometer on the surface of the metal layer; repeat the above steps to treat the other side of the porous membrane.

The present invention is based on the principle of electric double layer effect power generation: the electrolytic solution passes between two metal surface electrodes, and excess charges with opposite signs appear on the liquid surface near the metal surface, thereby causing a potential difference between the phases; an external circuit is connected between the metal surfaces, The electrolyte solution continuously passes between the electrodes on the two metal surfaces, and the positive and negative ions in the electrolyte move rapidly to the two poles under the electric field, and form a tight charge layer on the surface of the two electrodes, that is, the electric double layer; the external circuit and metal electrodes, electrolyte A complete circuit is formed, which produces a current voltage.

In the present invention, the inner wall of the pores of the porous membrane is coated with a metal layer. When the electrolyte is driven by pressure to flow through the pores, the ions in the electrolyte generate an electric double layer effect in the pores, and a current is formed in the closed circuit formed by the pores and the external circuit. After the current or voltage signal in the circuit is collected, the value of pressure/pressure difference is obtained through calculation.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. The device of the present invention does not have any mechanical rotating parts, has simple structure, is stable and reliable, has no pollution and noise, does not need to provide external power supply equipment for driving, and is very friendly to the environment;

2. The present invention is applicable to fluids such as liquid or gas, and even the fluid may contain solid suspended particles;

3. The invention has high sensitivity and large measurement range, and can realize measurement in different ranges according to different pore sizes and liquids containing different ions;

4. The invention can make a fixed device or a plug-and-play device.

Description of drawings

Figure 1 is a schematic diagram of the principle of the electric double layer effect.

Fig. 2 is a flow chart of magnetron sputtering treatment of alumina nanoporous film.

Fig. 3 is a schematic diagram of the pressure and differential pressure measuring device of the present invention. Among them, 1 is an electrolyte; 2 is a tough film, and the tough film constitutes a pressure-sensitive air bag 5 and a pressure-sensitive air bag 6; 3 is a porous film; 4 is an elastic material; 5 and 6 are pressure-sensitive air bags; 7 is a metal wire; A signal acquisition device; 9 is a channel whose inner wall is coated with a metal layer.

Fig. 4 is a graph showing the relationship between the pressure difference and the voltage of the pressure-sensitive airbags on both sides.

Detailed ways

The present invention will be described in further detail below in conjunction with specific embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

The aluminum oxide nanoporous membrane used in the examples was purchased from Shanghai Nateng Instrument Co., Ltd.; the thin film was purchased from Shenzhen Hongmei Film Co., Ltd.

A pressure and differential pressure measuring device based on the electric double layer effect of the pore, including a porous membrane, an elastic material surrounding the porous membrane, two pressure-sensitive airbags made of a tough film, a metal wire wrapped with an insulating material, and a device A signal acquisition device outside the pressure-sensitive airbag; wherein, the pore size of the porous membrane is micron-scale or nano-scale, the inner wall of the porous membrane is coated with a metal layer, and the metal layer is welded with metal wires, and the metal wires are drawn out The pressure-sensitive airbag is connected with the signal acquisition device; there is a pressure-sensitive airbag on each side of the porous membrane, and the porous membrane and the pressure-sensitive airbag are sealed by an elastic material surrounding the porous membrane; the pressure-sensitive airbag contains electrolytic When the electrolyte passes through the micro-nano channels of the porous membrane, an electrical signal is generated due to the double-layer effect, and the electrical signal is transmitted to the signal acquisition device through the metal wire; the signal acquisition device converts the electrical signal into a pressure or pressure difference value output. the

Example

(1) Carry out magnetron sputtering treatment on the alumina nanoporous film, the process is shown in Figure 2: firstly, a layer of 15 nm thick chromium and A layer of silver with a thickness of 100 nm, and then solder a silver wire wrapped with insulating material on the surface of the silver layer, and then deposit a layer of silver chloride with a thickness of 100 nm on the surface of the silver layer by electrodeposition; On the other side of the film, a layer of chromium with a thickness of 15 nm and a layer of silver with a thickness of 100 nm were sequentially sputtered by magnetron sputtering, and then a silver wire wrapped with an insulating material was welded on the surface of the silver layer to complete the pairing. Magnetron sputtering treatment of alumina nanoporous films.

(2) As shown in Figure 3, the aluminum oxide nanoporous membrane 3 processed by magnetron sputtering is inserted into the annular elastic material 4 with a certain mechanical strength, and the silver wire 7 is led out of the separator 4, and the aluminum oxide nanoporous membrane 3 and the elastic material 4 are sealed; there is a pressure-sensitive airbag 5 and a pressure-sensitive airbag 6 made of a tough film 2 on both sides of the aluminum oxide nanoporous membrane 3; the edges of the pressure-sensitive airbag 5 and the pressure-sensitive airbag 6 are sealed on the Elastic material 4 in. The electrolyte 1 (NaCl solution with a concentration of 10 ^-6 mol/L) is filled into the pressure-sensitive airbag 5, the aluminum oxide nanoporous membrane 3 is completely wrapped by the pressure-sensitive airbag 5 and the pressure-sensitive airbag 6, and the silver wire 7 is wrapped with The insulating material can be isolated from the electrolyte 1, and the silver wires are led out from the pressure-sensitive airbags 5 and 6, and the silver wires 7 are connected with the signal acquisition device 8 to form a closed circuit.

(3) Measuring pressure: If the pressure of the pressure-sensing airbag 5 is known, connect the pressure-sensing airbag 6 to the measured fluid or immerse it in the measured fluid, and the fluid in the pressure-sensitive airbag 6 can reflect the pressure of the measured fluid. The pressure difference formed on both sides of the porous membrane 3 makes the ionic liquid pass through the nanometer-sized pores 9 at a certain flow rate, and produces an obvious electric double layer effect. The current formed by the electric double layer effect can be transmitted through the metal layer and the silver wire on the inner wall of the hole Out, the electrical signal is displayed in the data acquisition device. According to the electrical signal (current or voltage), environmental pressure, material properties and geometric properties of the channel, the electrical signal is converted into differential pressure data, so as to measure the pressure of the fluid.

(4) Measuring the pressure difference: the pressure-sensitive airbags 5 and 6 are respectively connected to the measured fluid of unknown pressure, and the electrical signal can be obtained as in the signal generation process in step (4) and converted into pressure difference data. When the device is running:

A reaction occurs on the Ag electrode: Ag+Cl ^- →AgCl+e ^- ,

A reaction occurs on the AgCl electrode: AgCl+ e ^- -→Ag+ Cl ^- .

When the cross-section of the channel 9 is rectangular, the height is 55 nm, the width is 100 μm, and the length is 1 cm, the relationship between the pressure difference on both sides of the pressure-sensitive airbags 5 and 6 and the generated voltage is shown in Figure 4.

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In the embodiment of the present invention, the effective size of the channel can be micron or nanoscale, depending on the design requirements; the present invention can make a fixing device, and can also make a probe device; the NaCl solution in the device can be replaced by other electrolytes; the electrodes of the device In addition to the Ag and AgCl electrode pair, it can also be an electrode pair used in conjunction with other electrolytes. For example, if a liquid with a certain concentration of carbonic acid is used as an electrolyte, Ag and Ag ₂ CO ₃ can be used as an electrode pair. When the device is running:

A reaction occurs on the Ag electrode: Ag+CO ₃ ^2- → Ag ₂ CO ₃ +2e ^- ,

A reaction occurs on the Ag ₂ CO ₃ electrode: Ag ₂ CO ₃ +2e ^- →Ag+CO ₃ ^2- .

The technical solution of the present invention has been described in detail above in conjunction with specific embodiments and accompanying drawings, but the present invention is not limited to the above-mentioned embodiments, within the scope of knowledge possessed by those of ordinary skill in the art, it can also be achieved without departing from the purpose of the present invention. Various changes are made.

Claims (3)

1. pressure and a differential pressure measurement device, is characterized in that: the pressure-sensitive air bag of comprise perforated membrane, be looped around resilient material around of perforated membrane, two being made up of toughness film, be enclosed with the metal wire of insulating material and be placed in the signal pickup assembly of pressure-sensitive air bag outside; Wherein, the aperture of described perforated membrane is micron order or nano-grade size, and the duct inwall of perforated membrane is coated with metal level, and soldered on metal level have a metal wire, and metal wire is drawn pressure-sensitive air bag and is connected with signal pickup assembly; Respectively there is a pressure-sensitive air bag both sides of perforated membrane, between perforated membrane and pressure-sensitive air bag, seal by being looped around perforated membrane resilient material around; In two pressure-sensitive air bags, fill the electrolytic solution of variable concentrations,, because electrostatic double layer effect produces electric signal, electric signal is sent in signal pickup assembly by metal wire when in the micro-nano duct of electrolytic solution by perforated membrane the; Electric signal is converted into the output of pressure differential pressure numerical value by signal pickup assembly.

2. device according to claim 1, is characterized in that: described perforated membrane is aluminium oxide nano perforated membrane, fritted glass fiber or monox nanometer perforated membrane.

3. device according to claim 1 and 2, it is characterized in that: the method for the duct inwall metal cladding of described perforated membrane, comprise the following steps: first adopt the method for magnetron sputtering to make the metal level of nano thickness in perforated membrane one side, then at the soldered metal wire that is enclosed with insulating material of layer on surface of metal, then adopt the method for electro-deposition at the metal halide of layer on surface of metal plating one deck nano thickness; Repeating above-mentioned steps processes the opposite side of perforated membrane.

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