Study On Regeneration Behavior Of Electrochemical Sweat Sensor Based On MEMS GHz Ultrasound

Wearable devices,with characteristics of convenient carrying and fast detection,is important trend of intelligent medical development.Compared with blood,sweat also contains a large number of electrolytes and metabolites related to human health,and sweat detection is non-invasive.Electrochemistry is fast,high sensitivity and continuous detection method.However,the electrode of sweat sensors is easy to be polluted by sweat,resulting in the decline of sensitivity and the inability to detect continuously.Ultrasonic cleaning is widely used in various places,but the traditional ultrasonic devices are large and can not be integrated into wearable devices,ultrasonic cavitation will damage the electrode.In this paper,a micro ultrasonic device and a Au electrode fabricated by MEMS technology are used to build an ultrasonic electrochemical microfluidic sweat detection system.Ultrasonic sound flow realizes the regeneration of detection electrode.(1)A two-dimensional microfluidic simulation model is constructed to obtain the shear stress distribution on the electrode surface.Cavity diameter,height and ultrasonic power on the cleaning effect are analyzed from theoretical simulation and experimental research.The cavity diameter of 6 mm and height of 1mm are optimal respectively.In the experimental study,the signal characteristics of the electrode were characterized by cyclic voltammetry.After ultrasonic cleaning for 20 min,the electrode signal of the ordinary gold film recovered 80% and the electrode modified with gold nanoparticles recovered 85% respectively.(2)After the electrode cleaning,the stability of gold nanoparticles stimulated by ultrasound was studied to judge the damage of ultrasound to the electrode.The results show that the nanoparticle density at the five data sampling points does not decrease,and there is no trace of particle falling off in the SEM image.Ultrasound can clean the pollutants without damaging the gold nanoparticles and the electrode.The research results of this paper provide a new solution to the sweat pollution problem of wearable sweat sensor.