Sweat Biosensors Based On Electrochemical Principles

As a product of human metabolism,sweat is indispensable for the regulation of body temperature.In addition,sweat is also rich in biochemical information,such as inorganic ions,p H,glucose,lactic acid,protein and so on.Analytical measurements of biochemical components in sweat contribute to metabolic analysis,exercise health management,and disease diagnosis.Traditional sweat analysis often relies on large-scale biochemical analysis equipment such as high performance liquid chromatography,mass spectrometry,etc.,which are incapable of in situ analysis of sweat.In addition,the existing miniaturized sweat analytical devices lack an effective sweat manipulation unit,which are often accompanied by sweat evaporation,aggregation,and reabsorption on the skin surface during analysis.Thus,accurate and continuous analysis of sweat can not be achieved.In this paper,we have fabricated miniaturized electrochemical biosensors for the detection of inorganic ions in sweat,which mainly includes the following two aspects:In the fist part,an ammonium ion sensor based on ion selective electrode was fabricated for the detection of ammonium ions in sweat.The selectivity and stability of the sensor were investigated.The sensor can realize the in-situ rapid analysis of ammonium ions in sweat.In addition,in order to achieve miniaturization of the device,a portable smart phone is used as a signal acquisition and processing device.The analysis results can be presented on the mobile phone in real time,which greatly simplifies the entire sensing system.In the second part,in terms of sweat control,we designed a wearable microfluidic chip based on capillary force for continuous analysis of sweat.The continuous collection and transportation of sweat is realized by the capillary action of porous materials such as cotton thread and hydrophilic microchannel.The evaporation,aggregation and reabsorption of sweat on the skin surface are avoided.In addition,the microfluidic chip also integrates a sodium ion selective electrode as a detection unit to achieve continuous collection and detection of sweat.The sensor also has the advantages of easy processing and miniaturization,which provides a new idea for simple and reliable continuous and accurate analysis of sweat.The innovation of the paper: the use of smart phones to analyze and process the signals of electrochemical sensors,making the entire sensing system more compact and portable.The capillary-driven microfluidic chip is applied to the manipulation of sweat to achieve accurate and continuous sweat analysis.