Studies On Solid-state Potentiometric Sensing And Wearable Electrochemical Sensing Technology

In recent years,environmental pollution and human health have been widely concerned.With the development of science and technology,electrochemical sensing technology has been continuously applied to the detection of the environment and health.As one of the electrochemical sensing technologies,potentiometric sensing technology has been used by many researchers in environmental monitoring,on-site analysis and other fields,due to its excellent detection performance,low power consumption,simple equipment,low-cost and easy to use.Among them,the solid-state potentiometric sensor has been continuously developed and applied in recent years.Compared with the traditional internal liquid-filled ion selective electrode,the all-solid-state potentiometric sensor integrated with nanomaterials?carbon nanomaterials,metal nanomaterials,etc.?as the ion-electron conversion layer,which have a good conductivity,and relying on a selective and sensitive membrane or biometrics to interact with the targets,which could cause the change of potential to implement the detection.With the born of solid-state electrodes,It overcomes the problem that ion-selective electrode needs to be filled with the internal liquid.The solid-state electrode has the advantages of being easy to miniaturize in size,convenient to carry,and more advantageous for application to a complicated environment.In recent decades,with the continuous development of solid-state potentiometric sensors,the combination of portable,wearable and intelligent detection devices have enabled solid-state electrodes to be successfully applied in the field of medical and food safety for on-site analysis and real time monitoring.In recent years,wearable sensing technology has received extensive attention,not only in the field of research has been well developed,but also has the gradually development of commercialization.Most of the wearable sensors in commercialization are mainly prepared to be able to intelligently adapt to mechanical,electrical and optical techniques to measure body metrics.Such wearable devices involve realizing the miniaturization of sensing technology,maintaining the mechanical properties of the sensing device,flexible and stretchable,and the development of supporting software for the increasing data measurement.The wearable sensors that have been implemented are mainly to measure physical indicators of the body,such as heartbeat,step number and so on.There are still significant challenges for wearable chemical sensing system.For example,when a permanent wearable sensor is used for testing,it is required to have a long-term stable performance,and a textile type wearable sensor needs to satisfy the performance of cleaning.As a liquid secreted by the human body,sweat contains many substances that can be the health indicators of the human body.It has a promising development for the application with wearable sensors,such as detecting lactic acid,glucose,cortisol and other chemicals in sweat.Therefore,in order to overcome the challenges faced by wearable electrochemical sensors in the detection,it is very significant to make a wider variety of wearable electrochemical sensors for human health monitoring.In this paper,the solid-state potentiometric sensing technology as the one of the most important detection method in the field of electrochemistry,combing with wearable sensing technology,is committed to the realization and the development intelligent sensors.Therefore,taking advantage of solid state sensing technology and wearable sensing technology,the new-receptor based potentiometric sensor and wearable sensor were dedicated to the detection of analytes in the fields of environmental and health.The main content is divided into several sections as follows:In the first place,we studied the solid-state lead ion(Pb²⁺)potentiometric aptasensor based on portable gold electrodes.Potentiometric aptasensors enhanced by integrating advanced nanomaterials are of particular interest for the detection of multiplex species?e.g.,proteins,bacteria,micro-organisms?due to their low cost,ease of operation,and low detection limits.However,potentiometric detection of small ionic species aptasensor is still challenging.This article describes the first example of a label-free G-quadruplex-based potentiometric aptasensing platform for the detection of Pb²⁺.Polyion oligonucleotide-labeled gold nanoparticles?AuNPs-DNA?as probes are modified on Au electrode,providing high-density negative charge on the electrode surface.These signal-amplifying probes can selectively form G-quadruplexes with the presence of Pb²⁺ions and reduce the negative charges on the electrode surface,hence achieving potentiometric detection of Pb²⁺ions with high selectivity.The AuNPs-DNA-based aptasensor shows an acceptable sensitivity over a wide range from10^-1111 to 10^-6?M with a detection limit of 8.5 pM.Furthermore,confirmed by coupled plasma mass spectrometry,the sensing platform is capable of performing effective and accurate detection of Pb²⁺level in real water samples.The presented aptasensor offers a fast,convenient,low-maintenance,and highly sensitive alternative for on-site water pollution detection.Based on the previous work,an solid-state potentiometric aptasensor array based on a multichannel disposable screen-printed carbon electrode?SPCE?was demonstrated for the simultaneous detection of Hg???,Cd???and As???by open circuit potential?OCP?technology.The potential of the channel with an internal calibration DNA sequence?IC-DNA?was employed as the internal calibration potential?ICP?to subtract the background signal generated by the detection system,providing a built-in correction methodology.As a result,the developed aptasensor array showed high sensitivity and accuracy for detecting Hg???,Cd???and As???without mutual interference or interference from other ions.The linear response ranged from 2.5 pM to 2.5?M,and the detection limits for Hg???,Cd???and As???were 2.0,0.62,and 0.17 pM,respectively.Furthermore,the potentiometric aptasensor array was successfully applied for the simultaneous detection of three ions in real samples.The results obtained from the developed approach agreed well with the results obtained from inductively coupled plasma mass spectrometry.In recent years,there has been an increasing interest in wearable technology,which led to increasing research efforts to develop non-invasive biosensor based detecting platforms.In this paper,a stretchable textile-based wearable potentiometric sensor was developed for the first time to test glucose in artificial sweat.In this work,the use of specially formulated printable and stretchable carbon inks,combining with carbon nanotube?CNT?and elastic polyurethane adhesives,as well as cleverly designed serpentine printed electrode,further increased the stretching ability of the electrode.Due to the unique design of the electrode,making the electrodes can be repeatable printed with the use of CNT based stretchable ink,and also making the polymer binders and the stretchable ink combine well,leading to the stretchable CNT ink and Ag/AgCl ink both have strong adhesion to textile substrate.Furthermore,the equipment can stand the test of mechanical properties,showing the integrity of structure and performance during stretching and bending deformation.Consequently,we used glucose oxidase?GOx?and bimetallic nanomaterial modified electrode to prepare glucose potentiometric sensor,the glucose sensor can achieve good test performance.Among them,the detection limit of the potentiometric glucose sensor reaches 10?M,which can satisfy the demand of glucose detection in sweat.The developed stretchable textile based wearable sensor has a wide range of application and considerable development prospect,and it is possible to realize non-invasive biochemical sensing.Moreover,it can meet the real-time and on-site analysis,also has the ability of early warning of medical,health,and environmental.Cortisol is a common hormone and an important stress indicator in human body,the amount of cortisol is directly related to human health.Therefore,it is of great significance for this research.As an advanced new sensing technology,wearable sensors are of great significance for real time monitoring and medical diagnosis of human health.In this work,a wearable device is fabricated by using flexible and stretchable materials?stretchable silver ink?,and a molecularly imprinted polymer?MIP?based electrochemical cortisol sensor is combined to achieve a better fit with the wearer's skin.The sensor is more suitable for application to the human body during the real-time movement,realizing the non-invasive detection of cortisol in human sweat.In the current work,we first proposed an electrochemical sensor for the preparation of MIP by electropolymerization of Prussian blue?PB?and pyrrole?Py?with the cortisol as a template,and the detection of cortisol relies on the redox signal of Prussian blue.When the molecularly imprinted membrane selectively captures cortisol,it occupies the pores of the imprinted membrane,thereby hindering the electrons transfer during the PB redox reaction.As a result,it is that the change of PB signal and the logarithmic value of cortisol concentration show a good linear relationship.The novel wearable cortisol sensor has a good selectivity for cortisol,with a short interaction time?2 min?during the detection of cortisol.The MIP based flexible sensor for the detection of cortisol also shows a good linearity in the range of 10^-910^-55 M.A wearable sensor made of flexible and stretchable material is capable of resisting continuous mechanical deformation caused by skin abrasion.The device has been successfully applied to the real-time monitoring of cortisol from human subjects in different periods of time,in terms of the dynamics variation of cortisol during cycling exercises.At the same time,the wearable sensor was also used to detect the trend of cortisol in the saliva of the corresponding subject.Therefore,based on the performance of wearable cortisol sensor for real time and on-site detection,it can help people aware of the health and the physiological condition of the body,which is expected to be applied to clinical,military and biological aspects.