Controllable Preparation Of PDMS Wrinkles And Its Application In Flexible Sensing

Patterns in nature give people a feeling of beauty and in some cases,can also add mystery to the world of infinity.Similarly,patterns are also of great use in the course of human practice.They do not only change the surface topography of materials,but also provide new functionalities.Recently,the world is witnessing rapid development of flexible electronic devices.Lightweight,portable,foldable,and wearable electronic levices have greatly revolutionized people's traditional cognition and lifestyle,and the rend seems unstoppable.In this background,the patterning process as an important step in the electronic devices fabrication process,is of great significance for the ealization of the highly integrated and flexible structure of flexible electronic devices.Therefore,a new round of research and development associated with it has emerged.In his thesis,a simple method for the preparation of wrinkles is used.Taking the Au/DMS as an example,reversible control of a series of surface structural properties(such is wettability,surface Raman scattering enhancement and conductivity)for the wrinkled Au/PDMS materials are achieved by using the excellent tensile properties of DMS.The study in a certain sense proves the existence of a wettability transition state etween the Wenzel and Cassie states,and at the same time,the control of PDMS urface wettability proves that the ordered orientation of the molecular chain has a ertain influence on the contact angle of the surface;in addition,the effect of different urface morphology on the SERS and surface conductivity properties is also studied.This thesis is divided into four chapters,including Chapter 1-Introduction,Chapter 2-PDMS with different wrinkled surface topography,Chapter 3-The control of the structure properties of the wrinkled surface,Chapter 4-Conclusions and rospects.The main research content and related conclusions are as follows:In Chapter 1,literature review is made on the current microstructure preparation nethods,the surface properties of wrinkled flexible materials,and the development of lexible electronic devices.In Chapter 2,we explores different methods for the preparation of surface wrinkles n flexible substrates.The relevant contents are as follows:(1)The surface of wrinkled Au/PDMS was prepared by pre-stretching,and the effects of gold film thickness and pre-strain on the amplitude and period of wrinkling were investigated.(2)Explore the preparation methods of other surface wrinkles,such as:UV irradiation modified PDMS surface,template imprinting combined with pre-stretch to prepare the multilevel wrinkled surface,even using the template in nature to prepare the surface of the wrinkled PDMS,and the reasons and influencing factors were analyzed briefly.In Chapter 3,we investigate the reversible control of the structure properties of the wrinkle surface by strain is realized and the application of the flexible wearable prototype device is explored.The main contents include:(1)The surface wettability of wrinkled Au/PDMS during the application of strain from 0 to 60%achieves a reversible transition from hydrophobicity(?130°)to hydrophilicity(?80°),which involves the existence of a critical wetting state—"Cassie-like" state.(2)The enhancement factor of SERS of rhodamine 6G on the surface of wrinkled Au/PDMS was 1.6 × 103,and the enhancement factor decreased with the increase of applied strain.(3)The surface of wrinkled Au/PDMS has excellent electrical conductivity.After 100 cycles of?30%tensile strain,the electrical conductivity of the surface is still not significantly reduced,and it can still work under various deformation states.(4)The reversible control of the wettability by the strain on the other surface was relized,demonstrating the simplicity and generality of the method.In addition,the reversible control of the surface wettability of PDMS indicates the ordering orientation of the molecular chains in the polymer has a certain effect on surface wettability.(5)An application of a flexible wearable electronic prototype device was explored to achieve effective signal detection for different strain states,pulse,and vocal cord vibrations.In Chapter 4,we summarize the main content of this paper,and plans the future direction of the study.The innovations of this paper include:(1)The reversible control of the surface structure properties of wrinkled Au/DMS by strain is realized.(2)The existence of a critical wetting state between the Wenzel and Cassie states s proved.(3)Shows the effect of the ordered orientation of the polymer chain on the surface wettability.