Construction Of Novel Wearable Biosensors And Their Researches On Sweat Analysis

Sweat contains a lot of physiological information related to the body’s functional metabolism.The detection of physiological components in sweat can assist in the prevention and diagnosis of diseases.Compared with blood analysis,sweat analysis has advantages,such as non-invasiveness,portability and persistence.Sweat-based wearable sensors can achieve non-invasive monitoring of biomarkers from sweat and continuous tracking of real-time health status.Therefore,wearable sweat sensors have promising applications in the fields of health management and disease diagnosis.However,wearable sweat sensors still have some practical problems in terms of construction and sweat analysis,such as the inability to provide continuous collection of sweat samples,damage to the skin by chemical reagents,low sensitivity and poor stability of the sensors or the difficulty of integrating multiple modules.These issues limit the widespread use of wearable sweat sensors.Therefore,the development of highly sensitive,stable and integrated wearable biosensors is significant for further commercialization and advancement of sweat sensing technology.In this dissertation,an in-depth study on sweat analysis was conducted with the aim of solving the problems in the construction and application of wearable sweat sensor.First of all,in order to solve problems such as the evaporation of sweat samples and skin contamination,a microfluidic-based wearable sweat sensor integrated check valves and embedded with new colorimetric reagents was developed to achieve in situ collection of sweat samples and high-precision colorimetric determination of glucose in sweat.Secondly,to address the issues related to the immobilization of enzymes and the poor stability of sensors,the stability of the enzyme-based electrochemical sensor was improved by loading tyrosinase on the surface of zeolitic imidazole ester skeletal material8/graphene oxide(ZIF-8/GO)composite.A wearable electrochemical sensor was developed by combining a wireless electronic readout device to realize the realtime and continuous monitoring of the metabolized levodopa in sweat.Finally,the enzyme-based flexible wearable electrochemical sensor was further developed by modifying hydrophilic zeolitic metal azolate framework-7(MAF-7)encapsulated uricase and integrating a simple microfluidic chip and a wireless electronic readout device,which was for highly stable and selective detection of uric acid in a complex sweat environment.1.Firstly,in order to solve the problems of sweat samples evaporation and skin contamination in the process of sweat testing,a microfluidic chip with integrated check valves was designed,and the collected sweat was detected in a colorimetric system of glucose oxidase-peroxidase-o-dianisidine reagents.It was found that the colorimetric sensor chip has high sensitivity,high repeatability and accuracy for the detection of low concentrations of sweat glucose.The design of the microfluidic chip with integrated check valves not only solved the problem of evaporation and quantification of sweat samples,but also reduced the risk of damage to the skin caused by the backflow of chemical reagents,and improved the accuracy of glucose detection in sweat.2.Secondly,a portable non-invasive metal-organic framework/graphene oxide integrated enzyme-based wearable electrochemical sensor was developed for levodopa monitoring in sweat.The ZIF-8/GO composite formed by growing ZIF-8 nanoparticles in situ on the surface of graphene oxide was used to load tyrosinase.Integrating with a wirless electronic readout device enabled communication between the sensor and a smartphone application for continuous and real-time analysis.The sensor was found to have a wide linear response range from 1 to 95μM,a detection limit of 0.45 μM,good reproducibility,and excellent selectivity.In addition,the sensor exhibited high sensitivity and good stability in sweat detection due to solving the problems related to the reduction of catalytic efficiency.Therefore,the sensor has great potencial in continuous,noninvasive and immediate monitoring and management of drug levels in sweat.3.Finally,in order to advance the development of integrated and intelligent wearable sweat sensors,a non-invasive wearable electrochemical sensor based on uricase@MAF-7 was constructed for accurate and sensitive monitoring of uric acid,which was integrated a flexible microfluidic chip and a wireless electronic readout device.The flexible microfluidic chip enabled convenient and efficient collection of sweat samples.The hydrophilic MAF-7 protected the acativity of enzyme by encapsulating uricase,which solved the problems of enzyme aggregation and separation.The functional electrochemical sensor enabled the highly sensitive detection of uric acid in the concentration range of 2 μM-70 μM.The detection limit was as low as 0.34 μM.Additionally,the sensor could monitor uric acid in real sweat samples.This personalized wearable sweat sensing device is expected to be used to monitor disease-related metabolites in sweat.