A flower-shaped ZnO / PEDOT:PSS composite film, preparation method thereof, and flexible electronic skin sensor obtained therefrom

Abstract

The present invention belongs to the technical field of flexible electronic skin sensors and discloses a flower-shaped ZnO / PEDOT:PSS composite film, a preparation method thereof, and the resulting flexible electronic skin sensor. The ZnO / PEDOT:PSS composite film is prepared by coating the ITO surface of a cleaned and dried ITO / PET flexible substrate with a mask and magnetron sputtering ZnO. The film is then hydrothermally treated at 80-90°C, and the mask is removed to obtain a flower-shaped ZnO nanoarray. A PEDOT:PSS conductive layer is then prepared on the flower-shaped ZnO nanoarray using a droplet printing method. The flexible electronic skin sensor, produced based on the ZnO / PEDOT:PSS composite film, has the characteristics of high precision, a wide detection range, high integration, and multiple responses. It achieves pressure and tactile perception similar to that of human fingertip skin and can be applied to the field of human radial artery pulse monitoring.

Description

Technical Field

[0001] The present invention belongs to the technical field of flexible electronic skin sensors, and more specifically, relates to a flower-shaped ZnO / PEDOT:PSS composite film, a preparation method thereof, and the resulting flexible electronic skin sensor. Background Art

[0002] A pressure sensor is a device that detects and transmits pressure information, converting pressure signals into electrical or other output signals according to specific patterns and methods. It has broad application prospects in aerospace, intelligent buildings, railway transportation, smart healthcare, and the Internet of Things. Traditional pressure sensors based on semiconductor materials, metal materials, and piezoelectric crystals have advantages such as mature fabrication processes, high sensitivity, stable performance, and a wide detection range. However, they are relatively large and cannot withstand significant bending deformation, which limits their application in flexible wearables. In recent years, with the advancement of technology and increasing consumer demand, flexible pressure sensors based on functional materials have emerged. These sensors offer advantages such as light weight, small size, bendability, and deformability. They can be attached to curved objects and human skin, and have great application potential in wearable electronics, soft robotics, flexible displays, and electronic skin. To meet the application requirements of these fields, flexible pressure sensors must possess both high sensitivity and good bending properties. Therefore, the preparation of ultrathin pressure-sensitive responsive layers with surface microstructures for use in flexible electronic skin is of great significance.

[0003] Zinc oxide has the advantages of good biocompatibility, low toxicity and simple preparation methods, and has been widely used in various electronic devices and catalysis fields. However, the preparation of flower-shaped ZnO / PEDOT:PSS films and the application of highly sensitive, ultra-thin flexible electronic skin have not been reported. Summary of the Invention

[0004] To address the shortcomings and drawbacks of the aforementioned prior art, the primary objective of the present invention is to provide a flower-shaped ZnO / PEDOT:PSS composite film with a biomimetic microarray, which can be used to fabricate a highly integrated flexible electronic skin sensor.

[0005] Another object of the present invention is to provide a method for preparing the above-mentioned flower-shaped ZnO / PEDOT:PSS composite film, which uses indium tin oxide / polyethylene terephthalate (ITO / PET) as a flexible substrate and electrode to prepare a flower-shaped zinc oxide / poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid), abbreviated as ZnO / PEDOT:PSS composite film.

[0006] Another object of the present invention is to provide a flexible electronic skin sensor made of the above-mentioned flower-shaped ZnO / PEDOT:PSS composite film, which can respond to external pressure and monitor human pulse signals.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A flower-shaped ZnO / PEDOT:PSS composite film is prepared by coating an ITO surface on a cleaned and dried ITO / PET flexible substrate with a mask, magnetron sputtering ZnO, then performing a hydrothermal treatment at 80-90°C and removing the mask to obtain a flower-shaped ZnO nanoarray; and then preparing a PEDOT:PSS conductive layer on the flower-shaped ZnO nanoarray by a droplet printing method.

[0009] Preferably, the hydrothermal treatment time is 1 to 2 hours.

[0010] The method for preparing the flower-shaped ZnO / PEDOT:PSS composite film comprises the following specific steps:

[0011] S1. After cleaning and drying the ITO / PET flexible substrate, a mask was applied to the ITO surface and a ZnO seed layer was deposited by magnetron sputtering at 250-300W. The ZnO seed layer was then hydrothermally treated at 80-90°C and the mask was removed to obtain a flower-shaped ZnO nanoarray.

[0012] S2. A droplet printing system was used with a printing table temperature of 40-45°C and a droplet spacing of 10-12 μm. After printing, the printed PEDOT:PSS film was placed on the printing table to dry and then annealed at 90-100°C to prepare a PEDOT:PSS conductive layer on the flower-shaped ZnO nanoarray to obtain a ZnO / PEDOT:PSS composite film.

[0013] Preferably, the magnetron sputtering deposition time in step S1 is 25 to 30 seconds; the thickness of the ZnO seed layer is 40 to 50 nm; and the area of the flower-shaped ZnO nanoarray is (150 to 200) μm×(150 to 200) μm.

[0014] Preferably, the drying time in step S2 is 15 to 20 minutes, and the annealing time is 10 to 15 minutes.

[0015] A flexible electronic skin sensor is composed of several sensor units. The structure of the sensor unit is abbreviated as PET / Cu-ITO / ZnO / PEDOT:PSS / ITO-Cu / PET / PDMS. It is composed of the ZnO / PEDOT:PSS composite film on the ITO / PET flexible substrate and the PDMS film on the ITO / PET flexible substrate, and then connected to the ITO with copper wire.

[0016] Preferably, the PDMS film on the ITO / PET flexible substrate is prepared by coating PDMS on a PET base of the ITO / PET flexible substrate and then annealing the PDMS at 90-100°C.

[0017] The application of the flexible electronic skin sensor in human radial artery pulse monitoring.

[0018] Compared with the existing technology, the above technical solution has the following beneficial effects:

[0019] 1. The flower-shaped ZnO / PEDOT:PSS composite film prepared by the present invention uses indium tin oxide / polyethylene terephthalate (ITO / PET) as a flexible substrate and electrode to prepare a flower-shaped zinc oxide / poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid), abbreviated as ZnO / PEDOT:PSS composite film. First, a hydrothermal method is used to prepare a flower-shaped ZnO nanoarray. The area of the nanoarray can be controlled within the range of (150-200) μm×(150-200) μm. This method has low preparation cost. The preparation of a flexible film with a surface microstructure increases the sensitivity of the sensor in detecting shear force.

[0020] 2. The flower-shaped ZnO / PEDOT:PSS composite film prepared by the present invention has a biomimetic sensor response layer thin film microarray, and based on this, a flexible electronic skin sensor is prepared. It has high integration and realizes pressure and touch perception functions similar to human fingertip skin, improving the accuracy of electronic skin detection of external pressure distribution and surface texture recognition of objects. The flexible electronic skin sensor has high sensitivity and a wide detection range of up to 100kPa -1 The above-mentioned object surface texture detection limit reaches below 10μm, and the characteristics of high integration and multiple responses can realize pressure and tactile perception functions similar to the human fingertips. It is also light, soft and comfortable, which can reduce the burden and discomfort of users. It is used to monitor the human radial artery pulse signal and respond to external pressure. It has broad application prospects in the fields of motion analysis and health management. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1This is a flow chart for preparing the flower-shaped ZnO / PEDOT:PSS composite film and the flexible electronic skin sensor made therefrom of the present invention;

[0022] Figure 2 The surface morphology of the ZnO / PEDOT:PSS composite film prepared in Example 1;

[0023] Figure 3 This is the external pressure response diagram of the flexible electronic skin sensor in application example 1;

[0024] Figure 4 This is application example 1: monitoring of human radial artery pulse signals using flexible electronic skin sensors. DETAILED DESCRIPTION

[0025] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. The embodiments described herein are only used to illustrate and explain the present invention and should not be understood as limiting the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] Example 1

[0027] 1. The ITO / PET flexible substrate was cleaned and dried at 60°C for 30 minutes. A mask was then applied to the ITO surface. A 40nm thick ZnO seed layer was deposited by magnetron sputtering at 300W for 30 seconds. This was followed by hydrothermal treatment at 90°C for 1 hour. The mask was then removed to obtain a flower-shaped ZnO nanoarray.

[0028] 2. Using a droplet printing system, the printing table temperature was 40 ° C, the droplet spacing was 10 μm, and a PEDOT:PSS conductive layer was prepared on the surface of the flower-shaped ZnO nanoarray. In order to reduce the sheet resistance, 1-5 stacked layers were printed. The printed PEDOT:PSS film was placed on the printing table to dry for 15 minutes, and then annealed at 90 ° C for 10 minutes. A flower-shaped ZnO / PEDOT:PSS composite film with an effective area of 200 μm × 200 μm was prepared on an ITO / PET flexible substrate. Figure 1 shown.

[0029] Figure 2 The surface morphology of the ZnO / PEDOT:PSS composite film prepared in Example 1. Among them, (a) is the surface morphology of the flower-shaped ZnO nanomaterial. (b) is the surface morphology of the ZnO / PEDOT:PSS composite film. Figure 2It can be seen that a flower-shaped ZnO nanoarray was prepared on an ITO / PET flexible substrate, and a PEDOT:PSS conductive layer was prepared on it by droplet printing to obtain a ZnO / PEDOT:PSS film with a bionic structure.

[0030] Example 2

[0031] 1. The ITO / PET flexible substrate was cleaned and dried at 60°C for 30 minutes. A mask was then applied to the ITO surface. A 45nm thick ZnO seed layer was deposited by magnetron sputtering at 250W for 30 seconds. This was followed by hydrothermal treatment at 80°C for 1 hour, and the mask was removed to obtain a flower-shaped ZnO nanoarray.

[0032] 2. Using a droplet printing system with a printing table temperature of 45°C and a droplet spacing of 12 μm, a PEDOT:PSS conductive layer was prepared on the surface of a flower-shaped ZnO nanoarray. In order to reduce the sheet resistance, 1-5 stacked layers were printed. The printed PEDOT:PSS film was placed on the printing table to dry for 15 minutes and then annealed at 100°C for 8 minutes. A flower-shaped ZnO / PEDOT:PSS composite film with an effective area of 150 μm × 150 μm was prepared on an ITO / PET flexible substrate.

[0033] Application Example 1

[0034] 1. A PDMS solution (purchased from Dow Corning) was applied to a 120-grit sandpaper template and covered with an ITO / PET substrate. Using a roller-assisted pressing process, a uniform PDMS film was formed between the sandpaper and the ITO / PET substrate. Its microstructure mimicked the gradient structure from the epidermis to the dermis of human skin. The film was cured at 90°C for 1 hour. After removing the sandpaper template, a microstructured PDMS film was formed on the ITO / PET substrate. Annealing treatment was then performed at 100°C to tightly bond the PDMS and PET together, resulting in an ITO / PET / PDMS film.

[0035] 2. The ZnO / PEDOT:PSS composite film and ITO / PET / PDMS film prepared in Example 1 were combined on an ITO / PET flexible substrate, and two ITOs were connected with copper wires to serve as top and bottom electrodes, respectively, to form a flexible electronic skin sensor unit. The structure is abbreviated as PET / Cu-ITO / ZnO / PEDOT:PSS / ITO-Cu / PET / PDMS. Figure 1 As shown, several sensor units are combined into a flexible electronic skin sensor.

[0036] Figure 3The following is the external pressure response diagram of the flexible electronic skin sensor in application example 1. Among them, (a) is the current change generated by the flexible electronic skin sensor under a pressure of 200Pa. (b) is the current change generated by the flexible electronic skin sensor under a pressure of 1kPa. Figure 3 It can be seen that the single-point pressure sensor based on the ZnO / PEDOT:PSS response layer film achieves a good external pressure response. The flexible electronic skin sensor can respond to external pressure, and the current changes with the external pressure under different external pressure conditions. Among them, the PDMS film is attached to the surface of the PET flexible substrate to simulate the microstructure of the human fingerprint. The flexible electronic skin sensor is fixed on the test bench to detect the response to different pressures. The flexible electronic skin sensor can be used to monitor the radial artery pulse signal of the human body. The sensor is fixed to the radial artery pulse of the wrist of the tester (a healthy male) to monitor the human body's pulse signal. Figure 4 This is the application example 1 of flexible electronic skin sensor for monitoring human radial artery pulse signal. Figure 4 It can be seen that the flexible electronic skin sensor is able to monitor the human body's pulse signal. The monitored pulse frequency is about 60 beats per minute, which is consistent with the expected value of a healthy man in his 20s.

[0037] The above embodiments are preferred implementations of the present invention, but the implementations of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A flower-shaped ZnO / PEDOT:PSS composite film, characterized in that: The ZnO / PEDOT:PSS composite film is prepared by coating a mask on the ITO surface of a cleaned and dried ITO / PET flexible substrate, depositing a ZnO seed layer by magnetron sputtering at 250-300W, then hydrothermally treating the film at 80-90°C, and removing the mask to obtain a flower-shaped ZnO nanoarray. Furthermore, by droplet printing, the printing table temperature is 40-45°C, and the droplet spacing is 10-12 μm. After printing, the printed PEDOT:PSS film is placed on the printing table to dry, and then annealed at 90-100°C to prepare a PEDOT:PSS conductive layer on the flower-shaped ZnO nanoarray. The ZnO seed layer has a thickness of 40-50 nm, and the area of the flower-shaped ZnO nanoarray is (150-200) μm×(150-200) μm.

2. The flower-shaped ZnO / PEDOT:PSS composite film according to claim 1, characterized in that: The hydrothermal treatment time is 1 to 2 hours.

3. The method for preparing the flower-shaped ZnO / PEDOT:PSS composite film according to claim 1 or 2, characterized in that: The specific steps include: S1. After cleaning and drying the ITO / PET flexible substrate, a mask was applied to the ITO surface and a ZnO seed layer was deposited by magnetron sputtering at 250-300W. The ZnO seed layer was then hydrothermally treated at 80-90°C and the mask was removed to obtain a flower-shaped ZnO nanoarray. S2. Using a droplet printing system with a printing table temperature of 40-45°C and a droplet spacing of 10-12 μm, the printed PEDOT:PSS film was placed on the printing table to dry after printing, and then annealed at 90-100°C to prepare a PEDOT:PSS conductive layer on the flower-shaped ZnO nanoarray to obtain a ZnO / PEDOT:PSS composite film.

4. The method for preparing the flower-shaped ZnO / PEDOT:PSS composite film according to claim 3, characterized in that: The time of the magnetron sputtering deposition in step S1 is 25 to 30 seconds; the time of the drying in step S2 is 15 to 20 minutes, and the time of the annealing is 10 to 15 minutes.

5. A flexible electronic skin sensor, characterized in that: The flexible electronic skin sensor is composed of several sensor units. The structure of the sensor unit is abbreviated as PET / Cu-ITO / ZnO / PEDOT:PSS / ITO-Cu / PET / PDMS, which is composed of a ZnO / PEDOT:PSS composite film on an ITO / PET flexible substrate as described in claim 1 or 2 and a PDMS film on an ITO / PET flexible substrate, and then connected to the ITO with copper wire.

6. The flexible electronic skin sensor according to claim 5, characterized in that The PDMS film on the ITO / PET flexible substrate is prepared by coating PDMS on the PET base of the ITO / PET flexible substrate and subjecting the film to annealing treatment at 90-100°C.

7. Application of the flexible electronic skin sensor according to claim 5 or 6 in monitoring the radial artery pulse of a human body.

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