Flexible humidity sensor based on MoO x nanoparticle assembled materials, its assembling method and application

Abstract

The present invention discloses a flexible humidity sensor based on MoO x nanoparticle assembly materials, as well as an assembly method and application thereof. The sensor includes a flexible substrate, a MoO x nanoparticle lattice, metal microelectrodes, and an external conductance measurement circuit; wherein, the metal microelectrodes are disposed on the surface of the flexible substrate, and the MoO x nanoparticle lattice is deposited on the metal microelectrodes, and the external conductance measurement circuit is electrically connected to the metal microelectrodes. The nanoparticles in the present invention are generated by a gas-phase aggregation deposition method using a cluster beam deposition device. The humidity sensing material and the flexible device based on MoO x nanoparticles obtained by the method of the present invention can achieve sensitive detection of humidity at room temperature, with a response time of 2 s, and have the characteristics of operating at room temperature, high sensitivity, and fast response time. The impedance of the nanoparticle lattice is in the megohm order, and the power consumption is extremely small; it can be mass-produced and packaged in large areas.

Description

Technical Field

[0001] The present invention belongs to the fields of sensors and detection instruments, and particularly relates to a flexible humidity sensor based on MoO x nanoparticle assembly materials, and an assembly method and application thereof. Background Art

[0002] The detection of humidity is closely related to human life and is one of the most important issues in application fields such as agriculture, industrial production, environmental monitoring, aerospace, etc. With the development of society and the progress of technology, people's attention to flexible wearable electronic devices is increasing, and the development potential of electronic intelligent textiles is huge and the market prospect is extremely broad. Intelligent textiles are widely used in aspects such as human physiological signal monitoring, pressure and temperature / humidity detection, energy storage, gas sensors, and biosensors. Developing humidity sensing materials and devices suitable for flexible devices is particularly important. Finding a bendable sensing material that can achieve high-performance humidity sensing is the key.

[0003] The present invention proposes to couple a flexible substrate with MoO x nanoparticle assembly materials to achieve high-performance humidity sensing technology. In this material, MoO x nanoparticles play the role of humidity sensitivity. The flexible substrate is equipped with a planar thin-film electrode structure, which endows the device with flexible characteristics. The device has the advantages of high sensitivity and fast response. The response time is less than 2 s, and the humidity response value of the device reaches more than 800. The power consumption of the device can be controlled at the sub-milliwatt level, and there is no interference to the measurement during flexible bending actions, which can be controlled at the sub-milliwatt level, and there is no interference to the measurement during flexible bending actions. Summary of the Invention

[0004] Aiming at the problems of long response time and recovery time, poor response performance, and inability to achieve flexible sensing of current traditional humidity sensing materials, the purpose of the present invention is to provide a flexible humidity sensor based on MoO x nanoparticle assembly materials, and an assembly method and application thereof. The present invention utilizes the characteristics of the ultra-high specific surface area of nanoparticles and proposes to prepare MoO x nanoparticle assembly materials on the surface of a flexible substrate through cluster beam deposition technology to achieve flexible humidity sensing.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A flexible humidity sensor based on MoO x nanoparticle assembly materials, the sensor includes a flexible substrate, MoO x nanoparticle lattices, metal microelectrodes, and an external circuit for conductance measurement; wherein, the metal microelectrodes are arranged on the surface of the flexible substrate, and MoO xNanoparticle arrays are deposited on metal microelectrodes, and the external circuit for conductance measurement is electrically connected to the metal microelectrodes.

[0007] Further, the flexible substrate is made of a flexible material, and its material includes mica, polyimide, silicone rubber, fluororubber, polydimethylsiloxane or polyethylene terephthalate.

[0008] Further, the metal microelectrode is an interdigital electrode, made of gold or silver, with an electrode thickness of 100 - 300 nm and a width between two electrodes of 4 - 300 μm.

[0009] Further, the acquisition frequency of the external circuit for conductance measurement is 1 - 2000 Hz, and it is connected to the metal microelectrode through an enameled wire with a diameter of 10 - 100 μm.

[0010] The present invention is based on MoO x An assembly method for a flexible humidity sensor based on a MoO

[0011] 1) Select a flexible substrate with a smooth and clean surface and no obvious scratches;

[0012] 2) Print metal microelectrodes on the surface of the flexible substrate using processes such as mask - covered printing, electroplating or evaporation;

[0013] 3) Deposit MoO x nanoparticle arrays on the metal microelectrodes. The MoO x nanoparticle arrays are generated using a magnetron plasma gas cluster source with Mo as the target material and formed into a nanoparticle beam through differential pumping and deposited on the metal microelectrodes, and then aged in air to form MoO

[0014] 4) After the deposition of the MoO x nanoparticle arrays is completed, connect the metal microelectrodes and the external circuit for conductance measurement using enameled wire;

[0015] 5) Place the flexible substrate in different humidity environments, measure the current changes of the sample nanoparticle arrays in different humidity environments, and plot a humidity response curve (i.e., the relationship curve between current responsiveness and environmental humidity).

[0016] Further, the metal microelectrode is an interdigital electrode. When depositing MoO xThe specific process of the nanoparticle array is as follows: Place a high-purity Mo target on the sputtering gun of the cluster beam deposition equipment, place the interdigital electrode with a flexible substrate in the deposition chamber of the cluster beam deposition system, evacuate the entire device, and after the vacuum reaches the standard, introduce high-purity argon gas into the target gun as the sputtering gas and buffer gas, and apply a voltage to partially vaporize the Mo target into gaseous molecules or atoms. Then, the buffer gas collides with them to form nanoparticles, and a nanoparticle beam is formed by the method of differential pumping. Then, the beam is directed to the deposition chamber of the cluster beam deposition equipment and deposited on the surface of the interdigital electrode. Age in air at room temperature for more than 24 hours to oxidize the Mo nanoparticles to molybdenum oxide MoO x , thus obtaining MoO x nanoparticle array.

[0017] Furthermore, the air pressure in the sputtering chamber is maintained at 50 - 150 Pa, the sputtering power of the Mo target is set to 12 - 18 W, its sputtering current is 0.03 - 0.0375 A, the sputtering voltage is 400 - 480 V, and the sputtering time is 200 - 250 s.

[0018] The flexible humidity sensor based on the MoO x nanoparticle assembly material provided by the present invention can be well applied to detect the environmental humidity.

[0019] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The nanoparticles in the present invention are generated by the gas-phase aggregation deposition method using a cluster beam deposition equipment. The humidity sensing material and flexible device based on MoO x nanoparticles obtained by the method of the present invention can achieve sensitive detection of humidity at room temperature, with a response time as low as 2 s, and have the characteristics of working at room temperature, high sensitivity, and fast response time. The impedance of the nanoparticle array is in the megohm range, with extremely low power consumption; it can be mass-produced and packaged. Description of the Drawings

[0020] Figure 1 is a schematic structural diagram of the flexible humidity sensor of the MoO x nanoparticle assembly material of the present invention;

[0021] Figure 1 In [the figure]: 1 is a flexible substrate, 2 is a MoO x nanoparticle array, 3 is a metal microelectrode, and 4 is an external circuit for conductance measurement;

[0022] Figure 2 is the humidity response curve of the sensor of the present invention;

[0023] Figure 3 is the humidity hysteresis curve of the sensor of the present invention;

[0024] Figure 4 is the response curve of the sensor according to the present invention under different human breathing states;

[0025] Figure 5 is the humidity response curve of the sensor according to the present invention in the bent state and the flat state. Specific Embodiments

[0026] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0027] Embodiment 1:

[0028] The structural schematic diagram of the flexible humidity sensor based on the MoO x nanoparticle assembly material of the present invention is as shown in Figure 1 and includes a flexible substrate 1, a MoO x nanoparticle lattice 2, a metal microelectrode 3 and a conductance measurement external circuit 4; wherein, the metal microelectrode 3 is disposed on the surface of the flexible substrate 1, and the MoO x nanoparticle lattice 2 is deposited on the metal microelectrode 3, and the conductance measurement external circuit 4 is electrically connected to the metal microelectrode 3.

[0029] To prepare the flexible humidity sensor based on the MoOx nanoparticle assembly material of the present invention, the following steps are included:

[0030] 1) Select a clean and smooth flexible substrate insulating film without scratches. In this embodiment, polyimide is used, and the thickness of the selected film is 0.1 mm;

[0031] 2) Print interdigital electrodes on the upper surface of the flexible substrate, and prepare interdigital silver electrodes by mask evaporation in vacuum. The thickness of the electrode metal layer is about 100 nm, and the gap width between the positive and negative electrodes of the electrode is 100 μm;

[0032] 3) Place a high-purity Mo target on the sputtering gun of the cluster beam deposition equipment, place the interdigital electrode with the flexible substrate in the deposition chamber of the cluster beam deposition equipment, evacuate the entire device to make the vacuum in the deposition chamber reach 2×10 -4 Pa.

[0033] 4) Introduce 60 sccm of sputtering gas into the sputtering gun equipped with a Mo target, and introduce 80 sccm of buffer gas into the sputtering chamber (both the sputtering gas and the buffer gas use high-purity argon gas with a purity of more than 99.5%). At this time, the pressure in the sputtering chamber is 100 Pa. Then, introduce a power of 15 W into the sputtering gun equipped with a Mo target. At this time, the sputtering current is 0.036 A, and the sputtering voltage is 416 V. The sputtering time is 220 s. Turn off the sputtering gas and the power supply. After taking it out, age it in the air at room temperature for more than 24 hours, thereby obtaining MoO x nanoparticle dot matrix deposited on the interdigital electrodes.

[0034] 5) After the deposition of the MoO x nanoparticle dot matrix is completed, use enameled wire (diameter 100 μm) to connect the positive and negative electrodes of the interdigital electrodes to the external circuit for conductance measurement, and then a flexible humidity sensor is obtained.

[0035] Perform performance tests on the flexible humidity sensor prepared in Example 1 (the voltage of the external circuit for conductance measurement is 1 V, and the acquisition frequency is 1000 Hz):

[0036] Place the prepared sensor in a bottle equipped with different saturated salt solutions, namely saturated K 2 CO 3 aqueous solution (43% RH), saturated NaBr aqueous solution (57% RH), saturated NaCl aqueous solution (75% RH), saturated KCl aqueous solution (85% RH), and saturated KNO 3 aqueous solution (95% RH). That is, the interdigital electrodes with a flexible substrate are placed above the inside of a sealed bottle, and the saturated salt solution is placed below the inside of the bottle. Taking the saturated K 2 CO 3 aqueous solution (43% RH) as an example, it means that the environmental relative humidity in the space above the bottle is 43% RH at room temperature. Record the current changes at different humidities through the external circuit as shown in the appendix Figure 2 shown ( Figure 2 43%, 57%, 75%, 85%, and 95% in it respectively represent the relative humidity).

[0037] Perform hysteresis tests on the prepared sensor: The specific method is to test the response current (i.e., the current change under rising humidity) at relative humidities of 0%, 43%, 57%, 75%, 85%, and 95% successively, and then test the response current (i.e., the current change under falling humidity) at relative humidities of 95%, 85%, 75%, 57%, 43%, and 0% successively. The test results are as shown in Figure 3 shown. It can be seen from Figure 3 that the sensor of the present invention has good hysteresis.

[0038] The prepared sensor is subjected to humidity responsiveness testing: The flexible substrate of the sensor is attached to the inside of the mask, and the response current curves are tested under normal human breathing (15 - 20 times / min), first-level rapid breathing (30 - 40 times / min), and second-level rapid breathing (50 - 60 times / min) respectively. The results are as Figure 4 shown. It can be seen from Figure 4 this that the sensor of the present invention has good sensitivity and a fast response speed.

[0039] The prepared sensor is subjected to bending resistance testing: For the first sensor, the flexible substrate is in a flat state, and for the second sensor, the flexible substrate is bent to about 45°. They are respectively placed in a bottle containing saturated KCl aqueous solution (85% RH), that is, the interdigital electrode with the flexible substrate is placed above the inside of the sealed bottle, and the saturated KCl aqueous solution (85% RH) is contained in the lower part of the bottle. The changes in current under different states are recorded through an external circuit as shown in the appendix Figure 5 shown. The sensor of the present invention has good anti-bending humidity response performance.

[0040] The content described in this specification is only a list of the implementation forms of the inventive concept, and the protection scope of the present invention should not be regarded as limited to the specific forms stated in the embodiments.

Claims

1. Flexible humidity sensor based on MoO x nanoparticle assembled materials It is characterized in that The sensor includes a flexible substrate (1), a MoO x nanoparticle array (2), metal microelectrodes (3), and an external circuit for conductance measurement (4); wherein, the metal microelectrodes (3) are disposed on the surface of the flexible substrate (1), and the MoO x nanoparticle array (2) is deposited on the metal microelectrodes (3), and the external circuit for conductance measurement (4) is electrically connected to the metal microelectrodes (3); The flexible humidity sensor assembled from the MoO x nanoparticle assembly material has an assembly method including the following steps: 1) Select a flexible substrate (1) with a smooth and clean surface and no obvious scratches 2) Print metal microelectrodes (3) on the surface of the flexible substrate (1) by using a process of mask covering printing, electroplating or evaporation plating 3) Deposit MoO on the metal microelectrode (3). x The MoO nanoparticle lattice (2) is formed by using Mo as a target and generating a nanoparticle beam through a magnetron plasma gas aggregation cluster source and depositing it on the metal microelectrode (3) through differential pumping, and then aging in air to form the MoO x nanoparticle lattice (2). 4) MoO x After the deposition of the nanoparticle array (2) is completed, an enameled wire is used to connect the metal microelectrode (3) and the external circuit (4) for conductivity measurement; 5) Place the flexible substrate (1) in environments with different humidities, measure the current changes of the sample nanoparticle lattice in different humidity environments, and plot a humidity response curve In step 3), MoO is deposited on the metal microelectrode x The specific process of depositing the Mo nanoparticle array is as follows: Place a high-purity Mo target on the sputtering gun of the cluster beam deposition equipment, place the interdigital electrode with a flexible substrate in the deposition chamber of the cluster beam deposition equipment, evacuate the entire device, and after the vacuum reaches the standard, introduce high-purity argon gas into the sputtering gun as the sputtering gas, introduce high-purity argon gas into the sputtering chamber as the buffer gas, and apply a voltage to partially vaporize the Mo target into gaseous molecules or atoms. Then, the buffer gas collides with them to form nanoparticles, and a nanoparticle beam is formed by the method of differential pumping. Then, the beam is directed to the deposition chamber of the cluster beam deposition equipment and deposited on the surface of the metal microelectrode. Age in air at room temperature for more than 24 hours to oxidize the Mo nanoparticles in air to molybdenum oxide MoO x , thus obtaining the MoO deposited on the metal microelectrode x nanoparticle array; The air pressure in the sputtering chamber is maintained at 50 - 150 Pa, the sputtering power of the Mo target is set to 12 - 18 W, its sputtering current is 0.03 - 0.0375 A, the sputtering voltage is 400 - 480 V, and the sputtering time is 200 - 250 s.

2. The flexible humidity sensor based on the MoO x nanoparticle assembly material It is characterized in that The flexible substrate (1) is made of a flexible material, and its material includes mica, polyimide, silicone rubber, fluororubber, polydimethylsiloxane or polyethylene terephthalate 3. The flexible humidity sensor based on the MoO x nanoparticle assembly material, It is characterized in that The metal microelectrode (3) is an interdigital electrode, made of gold or silver, with an electrode thickness of 100 - 300 nm and a width between two electrodes of 4 - 300 μm 4. The flexible humidity sensor based on the MoO x nanoparticle assembly material It is characterized in that The acquisition frequency of the conductance measurement external circuit (4) is 1 - 2000 Hz, and it is connected to the metal microelectrode (3) through an enameled wire with a diameter of 10 - 100 μm 5. Use of the flexible humidity sensor based on the MoO x nanoparticle assembly material in detecting environmental humidity.

Images