Design And Sensing Behavior Research Of Flexible Chemical Sensors

Recent technological advances in the field of flexible electronics have underpinned the shift in the healthcare paradigm towards personal-centered health management model.Among them,flexible chemical sensor can detect biomarkers in human fluids and give human health status from the molecular level,which is a research hotspot at present.However,in most of articles on flexible chemical sensors that have been published,only a single biomarker has been detected,and few studies have been conducted on simultaneous detection of multi-component.In addition,when testing different parts of the human body,sensors need different degrees of deformation,and little research has been done on whether deformation affects the sensor's sensing behavior.Therefore,based on the design of flexible and stretchable conductive electrodes and chemical sensors,two kinds of flexible chemical sensors are constructed.The changes of electrical property of flexible conductive electrodes under bending,folding and stretching conditions are explored,and the effects of deformation on the sensing behavior of chemical sensors are studied.The main research contents of this paper include the following parts:1.Flexible conductive electrodes were prepared by two methods:?1?gold/polyimide electrodes were prepared by magnetron sputtering on flexible polyimide substrates.The electrodes were very flexible and their electrical properties remained stable under bending and twisting deformation;?2?serpentine-shaped copper electrodes were fabricated by blade cutters,and then encapsulated with Ecoflex.The electrode had excellent flexibility and could be deformed by bending,twisting and other deformation.Under these deformed conditions,the electrical properties remained stable.Through mechanical tests,it was found that the electrode also had good tensile properties.The maximum tensile strength could reach 120%.After 200times of cyclic stretching and folding,the electrical properties remained stable and the fatigue resistance was good.Therefore,both electrodes could be used as conductive electrodes for flexible chemical sensors.2.A flexible non-enzymatic glucose sensor was constructed using octahedral cuprous oxide?Cu₂O?particles as catalytic active material.The three-electrode structure of flexible sensor was fabricated by depositing patterned gold film on Polyimide by magnetron sputtering.A non-enzymatic glucose sensor was constructed using Cu₂O as working electrode,all-solid Ag/AgCl as reference electrode and gold film as counter electrode.The flexible sensor could withstand bending,folding,twisting and other deformation.Compared with the traditional conductive glass electrode modified with Cu₂O,the Cu₂O-based flexible nonenzymatic glucose sensor had higher catalytic performance.At the constant potential of 0.55 V,the sensitivity of the flexible non-enzymatic glucose sensor was 515.62?A/?mM.cm²?,the linear range was 10?M⁹mM,the detection limit was 10?M,and the response time was less than 5 s.In addition,the sensor had good anti-interference and stability against ascorbic acid,uric acid and various ions(such as K⁺,Na⁺,Mg²⁺,etc.).The sensor could be used to develop a sweat-based glucose sensor to detect the concentration of glucose in sweat.It is expected to realize the personalized monitoring and timely diagnosis of diabetes mellitus.3.A flexible and deformable multifunctional chemical sensor was designed.The sensing modules of glucose,pH and Na⁺were constructed by drop-coating and electrochemical deposition,and packaged on the Ecoflex substrate to explore the sensing behavior of the three sensing modules.The results showed that the multi-functional flexible chemical sensor could carry out biaxial stretching,bending,twisting and other deformation.Each sensor module had good sensitivity,linearity and anti-interference.In the deformation state,the sensor's sensing behavior had no obvious change and had good stability.In addition,the linear range of the three sensors covered the normal range of physiological substance content in human sweat,which provided a possibility for the detection of various biomarkers instead of blood in the future,and also provided an experimental reference for the early diagnosis of clinical diseases and personalized medical treatment.