Construction Of Flexible Wearable Electrochemical Sensor For The Detection Of Urea Concentration In Human Sweat

Recently,wearable devices have attracted extensive attention in the fields of real-time monitoring of body signals and metabolites in body fluids,owing to their conformal contact with soft skins or organs.Especially,with increasing recognition of the significance of body fluids,which are rich in physiological information,wearable epidermal electrochemical sensors for human sweat analysis have sprung up.At present,a series of flexible wearable biosensors have been developed for the detection of glucose,lactate,H+,Na+,K+ levels in the human perspiration.However,despite the above great achievement of wearable sensor,no device has been witnessed for the measurement of sweat urea,as an importrant metabolite in human liver related to many diseases.Therefore,developing wearable device for urea analysis is of great importance for personalized healthcare monitoring.As regards the detection of non-electroactive urea,urea sensors based on enzyme catalysis and molecular imprinting are commonly constructed on rigid electrodes.The enzymatic sensors usually achieve the detection by indirect determination of ammonia,the urease-catalysed hydrolysis products of urea.Then,the non-enzymatic sensors always actualize the urea determination by nano-material adsorption characteristics or molecular imprinting technology with electrochemical probe to acquire the change of electron transfer behavior at the interface.However,despite the progress of electrochemical urea sensors,there has been no report about flexible device for sweat analysis so far.In view of the research backgrounds and challenges,this paper aimed at developing flexible wearable electrochemical sensor to solve the problem of urea determination in human sweat.Herein,we constructed high-performance electrochemical sensors through molecular imprinting and enzyme sensing based on gold nanotube and carbon nanotube double networks flexible substrate,and realized the detection of urea levels in perspiration for the first time.The main works of this thesis are summarized as follows1.We constructed flexible wearable electrochemical sensor based on conductive networks of C-Au NTs hybrid nanocomposite by one-step electropolymerization to form Urea-PEDOT molecularly imprinted nanotubes.This electrochemical urea sensor showed excellent flexibility and selectivity,and satisfactory linear sensitivity to urea in physiological concentration range.The epidermal urea sensor was attached on the wrist of volunteers for sampling sweat,and the urea content in human sweat was analyzed effectively for the first time.2.To further realize the real-time monitoring sweat urea in situ,we developed flexible wearable electrochemical biosensor by loading urease and ammonium ion-selective membrane on the surface of C-Au NTs conductive networks.The urea was catalyzed hydrolysis by enzyme to produce ammonium,which would be detect by the electrochemical biosensor.The enzyme-based sensor still showed high sensitivity,high selectivity and good flexibility,which realized dynamic monitoring of urea level in solution.