Fabrication And System Verification Of Solid-state Micro Reference Electrode Based On Printing Process

With the advancement of science and technology,the era of Internet of Things is getting closer and closer,and human demand for sensors has been further improved.For advantages of realizing in situ signal amplification and integrated sensor arrays for multi-species and high throughput detection,ion–sensitive field–effect transistors(ISFETs)have been widely used to construct various chemical and biochemical sensing systems for applications such as in-vivo analysis,lab-on-a-chip,and electronic tongues.In the past,A lot of researches have been carried out on developing device structures being compatible to the industrial standard complementary metal-oxide-semiconductor(CMOS)integrated circuit processes,or using various new material FETs as low cost alternatives.In addition to that,the reference electrode(RE),which defines the measurement reference potential,is equally important to achieve proper operation of the overall system.The commercial glass based silver/silver chloride(Ag/AgCl)RE is commonly used in previous studies on ISFETs.However,glass tube structure of commercial RE with Cl~-ion rich solution inside has issues of mass-production,maintenance,and miniaturization for integration.Moreover,it is not suitable for many emerging flexible,wearable,or portable sensing applications.In previous studies of solid-state micro reference electrodes,the electrodes were fabricated through vacuum deposition and required additional metal layers underneath to form strong enough adhesion of the Ag layer to the substrate,resulting in high manufacturing cost.In terms of system integration,current ISFET tests rely mainly on testing instruments in laboratory,which are not suitable for on-site rapid detection applications.The main research content of this thesis will focus on solving the above key technical problems.The research results and contributions of the full text are as follows:1.The solid-state micro reference electrode was designed for ion biological and chemical detection for the requirement of ISFET application and the current problems.2.The large-area printing process is used to prepared micro reference electrode,which is suitable for common electrochemical detection.3.The prepared micro reference electrode was tested.The sensitivity,adhesion,storage life,stability,non-selectivity and micro structure of the electrode were characterized.4.The potential type electrochemical detection circuit was designed.The handheld electrochemical sensing system was built by using the micro reference electrode fabricated with printing process.The pH and Na~+?K~+ion detection applications were successfully realized.In general,the research work in this paper focuses on the fabrication of large-area micro reference electrodes with printing process.And the performance of electrodes have been comprehensively characterized.Finally,a handheld wireless chemical detection system was built with micro reference electrode to realize the detection of pH,Na~+and K~+.The problems of device integration and handheld detection system application of were solved in point-of-care testing.