| The research of wearable sweat sensor is one of the key points in the development of wearable electronic devices at present.The sensor can monitor the changes of biomarkers in sweat at the molecular level without invasive,and track the changes of physiological indicators of human body in real time,which has practical significance in the field of medical care and exercise monitoring.Compared with traditional testing,wearable electronic devices can detect human health conditions anytime and anywhere without the need for professional operators and expensive testing equipment,overcoming the limitations of centralized health care.Its core element is to meet people’s need for rapid diagnosis.However,sweat sensor is generally faced with problems such as long collection time of sweat and slow flow transmission of sweat,which limits the accuracy and speed of final detection.Therefore,optimizing the sensing mechanism of sweat collection and transmission has significant research value and application prospect.In this paper,through the research in the field of surface wettability,a two-dimensional liquid superspreading surface with better spreading performance is constructed,which can effectively reduce the time of sweat collection.On the other hand,based on this surface,a sensor platform conducive to sweat collection and transmission is constructed to improve the accuracy and speed of sweat detection and realize real-time detection of sweat.The specific research contents are as follows:(1)Preparation and performance testing of superspreading surface based on breath figure method. In this chapter,the influence of the micron structure of the surface on spreading is explored through the breathing template method,and a two-dimensional liquid superspreading surface with good spreading performance is constructed.The uniformity,aperture size and spacing of the porous template were regulated by breathing template method by adjusting the parameters of the film-forming material(type,amount and concentration of film-making liquid)and the film-forming environment(ambient temperature,humidity and etching time).The experimental results showed that the final prepared orderly porous membrane was white with uniform aperture and honeycomb structure.The superspreading performance of the superspreading surface obtained by polymer template reconfiguration can reach 509.561 mm~2/μL,which is better than the reported superspreading surface.SEM shows that the surface has a micron convex structure,and the convex is closely arranged on the surface in the way of honeycomb structure,and there is a certain gap at the bottom of the convex structure,the bottom surface of the convex structure is hexagonal;High-speed imaging shows that droplets spread along the honeycomb structure and gap of the surface,and the hexagonal regular surface of the bottom is more conducive to droplet spread.In addition,the key parameters affecting the overspreading performance(different convex structures and different splint structures)are summarized and the physical model is built.Through the mechanism analysis,the conditions conducive to spreading are obtained,which brings new inspiration for the study of surface wettability.(2)In view of the problems of the existing sweat sensors,such as long sweat collection time and slow transportation speed,the prepared superspreading surface was used as the flexible sensing base to realize the large area spreading of trace sweat and improve the detection efficiency.A simple sweat detection platform was constructed.Sodium ion selective electrode,potassium ion selective electrode and calcium ion selective electrode based on PEDOT electrode were used as the detection unit,and the electrochemical workstation and computer were connected to realize the real-time and multi-component detection of micro-sweat.The spreading process of deionized water and artificial sweat on the superspreading surface was tested by adding artificial sweat on the superspreading surface.The spreading property of artificial sweat on the surface reached 412 mm~2/μL,which proved that the substrate could achieve large area spreading of micro sweat and shorten the time of sweat collection and transmission.SEM characterization and charge storage density test showed that the surface microstructure of the PEDOT coated electrode could effectively increase the effective electrochemical reaction area of the electrode and improve the charge conductivity of the electrode.For sweat detection,the potential response of the ion-selective electrode was recorded by using sodium ion,calcium ion and potassium ion solution with concentration gradient.It was found that the concentration was linear with the corresponding open-circuit current,which verified that the sensor had good linearity.At the same time,it is verified that the prepared ion-selective electrode can only recognize specific ions,which is the basis and key to support the use of this method to carry out ion-selective electrode characterization of sweat concentration.It can be seen that the prepared sweat sensor based on the superspreading surface can realize the real-time detection of various electrolyte components in microdroplets.In summary,two-dimensional liquid superspreading surface has excellent spreading performance to shorten liquid collection and transmission time to realize real-time detection of sweat,which has a good application prospect and innovative ideas in the field of sweat sensing. |
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