Construction Of Porous Ultra-Thin And Flexible Silk Protein-Based Wearable Multifunctional Sensor Devices And Applications

This thesis addresses two aspects of porous ultra-thin flexible wearable silk protein-based sensors,the design and application study of bifunctional ultra-thin flexible PIC array structure-based SF-AAO-Au wearable SERS sensors and the electrostatic spinning large-scale preparation of all-fiber SF NF-Ag NWS composite wearable electronic skin and human health monitoring applications.The specific research contents are as follows:1.A novel approach was designed to prepare ultrathin layered flexible wearable SERS substrates:SF-AAO-Au sensors exhibit excellent SERS mechanical flexibility,homogeneity and sensitivity due to their effective SERS enhancement and highly ordered3D periodicity.The SERS performance was evaluated using Rhodamine（R6G）as the probe molecule and quantitative detection in the range of 10^-8-10^-5 M was achieved for R6G with a limit of detection（LOD）as low as 6.98×10^-8 M and enhancement factors（EF）as high as 3.3×10⁷.Biocompatible SF films with moisture-driven structures provided good skin adhesion in various fitness deformation tests.SF-AAO-Au was developed as a quantitative glucose sensor in the concentration range 10^-7-10^-3M with an LOD of 1.68×10^-7 M and qualitative detection of glucose in human sweat application.The“wipe-able”SERS sensing platform was used for ultra-sensitive on-site quantitative detection of trace pesticide residue molecules and achieved qualitative and quantitative analysis of thiram molecules in the range of 10-10⁶ ppt with a LOD of～5.7 ppt,which was much lower than the maximum residue limit（MRL）of 7 ppm in fruits set by the US Environmental Protection Agency（EPA）.This study enables the development of a dual-function SERS wearable sensor for the first time.2.A simple method was designed for the preparation of ultra-thin and porous flexible wearable electronic skin:Fibrous silk protein membrane（SF）prepared by electrostatic spinning technique and a silver nanowire（Ag NWS）conductive medium were vacuum filtered to form a large area fully fibrous composite membrane（SF NF-Ag NWS）.The inhibition zone diameter was 13.70 mm and 13.27 mm（initial diameter was 12.00 mm）with the killing efficiency of 56%and 50%for S.aureus and E.coli,respectively,which were demonstrated with excellent antibacterial property of SF NF-Ag NWS wearable material.Meanwhile,the SF NF-Ag NWS wearable material was applied to various parts of the human body to construct as wearable epidermal electrodes.The sensitive current response based on the single electrode mode enables the effective recognition and stable monitoring of whole-body physiological signals such as blinking,frowning and talking,as well as the motion signals of major joints such as joints,elbows,knees and necks.Finally,the ultra-thin porous SF NF-Ag NWS material is designed as a portable ECG monitoring device with electrode patches attached to the 12-lead electrocardiogram points of a healthy human body and transmits the measured ECG physiological signals to the self-developed smartphone application-Cloud Health app for real-time signal transmission.The developed multifunctional SF NF-Ag NWS wearable electronic skin in human exercise health monitoring application expansion and portable ECG monitoring system further promotes the rapid development of multifunctional comfortable and practical wearable sensors.