The Study On Stretchable Electronic Devices Based On Micro-Nano Structure

Stretchable electronic devices are a new form of extension of conventional electronic devices,which are a class of devices that do not break down under strain.In recent years,due to the improvement of the quality of life,various market segments have been rapidly developed,which has brought opportunities for the development and application of stretchable electronics.However,due to the gap between the performance of stretchable electronic devices and traditional devices,more in-depth research is needed from the aspects of materials and structures.At present,there are many ways to make electronic devices stretchable,and the method through some micro-nano structures has attracted the interest of researchers because of less restriction on materials.The main results of this thesis include the following parts:（1）A high-density crack structure is constructed in the plane graphite part of the vertical graphene（VGr）by the ultrasonic peeling method.The variable resistance stretchable strain sensor prepared based on this structure realizes high crack density and high tensile strength.At the same time,the tensile strain of the device reaches 100%,the average sensitivity factor is112.08 and the sensitivity factor can even reach 15288 in the strain range of 90～100%.The device also uses the high natural frequency of graphene sheets to achieve effective detection of sound waves（including loudness and sound frequency）.The maximum frequency detection range of sound waves is up to 2.5 kHz.The problem that the stretchable strain sensor is distorted in response to high-frequency vibration due to its slow response speed is solved,and the application of the stretchable strain sensor in high-precision sound measurement is expanded.（2）The VGr stretchable conductive film with a"zigzag"crack structure is prepared in a large area by a chemical peeling method.This method has the characteristics of good repeatability and simple operation.The final stretchable conductive material has stable performance and electrical conductivity.The resistance of the film changes by 18 times under100%tensile strain.Based on this electrode,a varactor stretchable strain sensor is fabricated.The maximum tensile strain of the sensor is 80%,and the sensitivity factor is about 0.9681,which is close to The theoretical limit value of this varactor strain sensor verifies the practicality and stability of the stretchable electrodes fabricated on a large scale using this method.（3）A BaTiO₃ material with elastomer composite intrinsically stretchable dielectric film was prepared,which combines the high dielectric properties of inorganic materials and the stretchability of elastomers.When the volume filling percentage of BaTiO₃is 0.3,the quasi-static dielectric constant of the composite material can reach 7,which is doubled compared with the dielectric constant of silicone rubber（PDMS）,and the frequency dielectric loss of the composite material Smaller frequency stability is also better,which expands the choice of dielectric materials for stretchable electronics.Based on this material,the influence of the dielectric layer on the sensitivity of the variable capacitance stretchable strain sensor was also explored,and it was found that this composite material filled with an organic matrix with an inorganic filler could improve the sensitivity of the sensor to a certain extent.（4）A stretchable conductive film based on VGr with a special buffer layer structure was prepared by adjusting the chemical peeling process,which has high stretchability and excellent resistance stretching stability.The resistance increased by 23%at the maximum tensile strain amount of 100%.The conductive film has a good thermoacoustic effect,and a stretchable sound generator has been developed using the thermoacoustic effect,which has almost same sound characteristics in the frequency range of 1 kHz to 22 kHz,the device can still output sound waves stably under the maximum tensile strain of 50%.（5）Using a stretchable substrate with a non-pre-stretched wrinkled network structure can simplify the patterning process of structural stretchable electronic devices,The substrate can be compatible with traditional device fabrication processes and improve the stretchability of the device.The stretchable gold wires with fine patterns evaporated through a mask only increase the resistance by 3%under a tensile strain of 30%.Using this substrate,thin film transistors based on inorganic oxide semiconductor materials with high mobility and high photostability were also constructed,and the inorganic oxide semiconductor films obtained certain stretchability by using a wrinkled network.In general,the author demonstrates a series of work around micro-nano-structured stretchable electronics and achieve certain results.The contradiction between stretchability and response frequency is solved by using micro-nano structures.A strain sensor with high stretchability（>100%）that can respond to high-frequency acoustic waves（>2500 Hz）is realized.Influenced by the resistive characteristics of VGr,it was found that VGr based on the buffer layer structure has a good thermoacoustic effect,and can emit 22 kHz ultrasonic waves in a stretchable state.A new stretchable lining with non-pre-stretched wrinkled network structure is proposed.According to the preparation method of the substrate,the oxide TFT is further constructed by using the stretchable substrate of the non-pre-stretched wrinkled network structure,which exhibits certain stretchability and field effect.These characteristic studies have achieved multiple breakthroughs,providing new ideas and opening up new methods for the application of stretchable materials in sensors.