Paper-based Wearable Electrochemical Sensors: A New Generation of Analytical Devices

Over the past few years, the emergence of electrochemical wearable sensors has attracted considerable attention because of their promising application in point-of-care testing due to some features such as high sensitivity, simplicity, miniaturization, and low fabrication cost. Recent developments in new fabrication approaches and innovative substrates have resulted in sensors able to real-time and on-body measurements. Wearable electrochemical sensors have also been combined with paper-based substrates and directly used on human skin for different applications for non-invasive analyses. Furthermore, wearable electrochemical sensors enable monitoring analytes in different biofluids without complex procedures, such as pre-treatment or sample manipulation. The coupling of IoT to various wearable sensors has also attracted attention due to real-time data collection and handling in remote and resource-limited conditions. This mini-review presents the significant advances in developing wearable electrochemical devices, such as sampling, data collection, connection protocols, and power sources, and discusses some critical challenges for higher performance in this field. We also present an overview of the application of paper as an intelligent substrate for electrochemical wearable sensors and discuss their advantages and drawbacks. Lastly, conclude by highlighting the future advances in wearable sensors and diagnostics by coupling real-time and on-body measurements to multiplexed detection of different biomarkers simultaneously, reducing the cost and time of classical analysis to provide fast and complete overall physiological conditions to the wearer.     

柔性可穿戴电子传感器研究进展

随着智能终端的普及,可穿戴电子设备呈现出巨大的市场前景.传感器作为核心部件之一,将影响可穿戴设备的功能设计与未来发展.柔性可穿戴电子传感器具有轻薄便携、电学性能优异和集成度高等特点,使其成为最受关注的电学传感器之一.综述了近年来柔性可穿戴电子传感器的研究进展,包括压阻、电容、压电、力致发光和摩擦电等信号转换机理,金属、无机半导体、有机和碳材料等柔性可穿戴电子的常用材料,柔性电子传感器的印刷制造及其在体温和脉搏检测、表情识别和运动监测等方面的最新应用,最后提出了柔性可穿戴电子传感器面临的挑战与未来发展方向.     

柔性可穿戴传感器件与储能器件的发展现状与挑战

随着人们生活质量与对可穿戴监测设备需求的提高以及物联网、人工智能和人机交互等科技水平的发展,能够对人体生命体征信号采集、转化与识别的可穿戴柔性电子装置成为连接智能生物与非智能机械装置的桥梁. 可穿戴柔性电子器件对人体生命体征信号的采集包括人体脉搏、温度、皮肤应变、呼吸和心跳等指标. 本文总结概述了近年来可穿戴柔性传感器对人体生命信号采集的现状以及存在的问题和挑战,并对可穿戴柔性供能器件做了简要的总结和展望.     

可穿戴电化学传感器件的研制及其应用

可穿戴电化学传感器件是一种可直接穿戴在身体特定部位、甚至植入用户体内的柔性电化学传感器。其具有简易性、便携性、灵活性等特点,可实时电化学监测与跟踪分析待测物,被广泛用于医疗保健、人体健康和环境监测等领域。该综述概括了可穿戴电化学传感器件的硬件设计与研制,及其在汗液检测、神经化学监测、现场分析检测（POCT）中的应用,总结和展望了可穿戴电化学传感器件的未来发展趋势,以期为可穿戴电化学传感领域的进一步发展提供参考。     

An Overview of Wearable and Implantable Electrochemical Glucose Sensors

Electrochemical glucose sensors have garnered considerable attention because of their attractive prospect in point-of-care testing (POCT). In this review, we firstly introduce the principles and challenges of electrochemical glucose sensors. Subsequently, we present an overview of the application of electrochemical glucose sensors and discuss their advantages and drawbacks. Wearable and implantable devices based on diverse target biofluid and platforms provide a considerable prospect of accurate and continuous monitoring. Thus, we believe that the future development direction of electrochemical glucose sensors is non-invasive, wearable devices and implantable devices with minimally invasive for continuous glucose monitoring in real time.     

微纳结构柔性压力传感器的制备及应用

柔性压力传感器是一种能够感知或监测外界压力变化的柔性电子器件,具备灵敏度高、形变灵活、制备工艺简单等特点,在可穿戴式电子产品、健康医疗、软体机器人、人机交互等新兴领域具有广泛而重要的应用。灵敏度、检测极限、响应时间与循环工作稳定性是柔性压力传感的核心性能指标,微纳结构的引入对提高柔性压力传感器综合性能具有重要作用。本文根据微纳结构的主要类型介绍了基于微纳结构的柔性压力传感器的最新研究进展,包括各种不同形貌微纳结构对柔性压力传感器性能的影响及其在柔性压力传感器中的应用,并对柔性压力传感器未来的发展提出展望。     

Advances in Medical Wearable Biosensors: Design,Fabrication and Materials Strategies in Healthcare Monitoring

In the past decade, wearable biosensors have radically changed our outlook on contemporary medical healthcare monitoring systems. These smart, multiplexed devices allow us to quantify dynamic biological signals in real time through highly sensitive, miniaturized sensing platforms, thereby decentralizing the concept of regular clinical check-ups and diagnosis towards more versatile, remote, and personalized healthcare monitoring. This paradigm shift in healthcare delivery can be attributed to the development of nanomaterials and improvements made to non-invasive biosignal detection systems alongside integrated approaches for multifaceted data acquisition and interpretation. The discovery of new biomarkers and the use of bioaffinity recognition elements like aptamers and peptide arrays combined with the use of newly developed, flexible, and conductive materials that interact with skin surfaces has led to the widespread application of biosensors in the biomedical field. This review focuses on the recent advances made in wearable technology for remote healthcare monitoring. It classifies their development and application in terms of electrochemical, mechanical, and optical modes of transduction and type of material used and discusses the shortcomings accompanying their large-scale fabrication and commercialization. A brief note on the most widely used materials and their improvements in wearable sensor development is outlined along with instructions for the future of medical wearables.     

微结构化柔性压力传感器的性能增强机制、实现方法与应用优势

柔性压力传感器具有易共形、高灵敏、快响应等特点,是发展物联网、可穿戴电子、触觉人工智能等领域的关键核心器件。通过敏感功能材料开发、功能层微结构设计、微纳制造方法优化等策略,可提升柔性压力传感器的综合性能,扩张其应用场景。其中,功能层微结构的创新设计被普遍认为是增强柔性传感器性能最有效的手段之一。本文综述了近年来基于微结构化的柔性压力传感器的最新研究进展,围绕微结构对于柔性压力传感器性能增强的机制、微结构的设计与实现方法以及微结构化柔性压力传感器在人机交互、医疗健康等领域的应用等方面进行详细阐述,并在此基础上对其未来发展方向进行展望。     

Electrochemical Mechanisms in Potentiometric Phosphate Sensing Using Pure Cobalt,Molybdenum and their Alloy for Environmental Applications

Phosphorus (P) is ubiquitous in the environment, but its measurement is costly and time-consuming. Sensor-based measurement shows potential, but selection of right metal remains the major challenge due to strong P species dependence on pH. This study examined the feasibility of pure cobalt, molybdenum, and their electrodeposited alloy, Co₆₃Mo₄₂ (wt %), as phosphate sensors. The cobalt, molybdenum and alloy exhibited mixed potential, Nernst potential, and oxidation-reduction (red-ox) mechanisms, respectively. Alloy showed good selectivity over a wide pH range, but high limit of detection and long response time (8–14 minutes). Yet, alloy provides a new opportunity for improving electrochemical phosphate sensors.     

量子点微型光谱传感技术在水质实时监测中的应用

随着我国城市化进程加快和工业化程度加大,水环境保护问题愈发突出。水质的实时监测是水质治理的重要前提之一。从水质实时监测发展历程中的各项技术谈起,介绍和比较多种光学传感法,并着重聚焦于新兴的量子点微型光谱传感技术。量子点光谱仪是基于胶体量子点材料的重建式微型光谱仪,具有成本较低、性能优良、发展潜力大等诸多优势,目前已实际应用到水环境实时监测中。最后总结并展望了水质实时监测技术未来的发展方向。     

高分子导电水凝胶的制备及在柔性可穿戴电子设备中的应用

水凝胶是具有高含水量、可变形性和良好生物相容性的材料,其中导电水凝胶具有良好的导电性、可调节的机械性及自黏附性等特征,逐渐成为制备柔性可穿戴电子设备的最佳候选材料。近年来,具有生物相容性、机械柔韧性和抗疲劳性的导电水凝胶得到广泛研究,能够实现多种生理信号和物理信号的监测及传输,促进了柔性可穿戴电子设备的发展。柔性可穿戴电子设备逐渐成为人机交互技术和人工智能领域的主要研究方向。导电水凝胶通过使用导电聚合物、导电填料、自由离子及其混合物来合成,根据导电机理,所制备的导电水凝胶可分为电子导电水凝胶、离子导电水凝胶和混合电子-离子导电水凝胶。本文讨论了导电水凝胶的制备方法,总结了导电水凝胶在可拉伸性、导电性、生物相容性和自修复性等功能方面的研究进展及其在柔性可穿戴电子设备中的应用,期望导电水凝胶可以取得更好的发展。     

基于碳纳米材料的无酶电化学传感器同时检测抗坏血酸、多巴胺和尿酸

人体中抗坏血酸（AA）、多巴胺（DA）和尿酸（UA）的浓度失调可能导致一系列疾病,如癌症、老年痴呆症、高尿酸血症等,而且这三个物种通常共存于体液中,有接近的氧化还原电位,因此实现三者的同时检测,既具有一定的难度,又具有极其重要的现实意义。近年来用于同时检测AA、DA和UA的电化学传感器取得了令人瞩目的进展,其中碳材料因其成本低廉、导电性好、稳定性好、比表面积大等特点逐渐引起人们的广泛关注。本文综述了基于碳材料构筑的检测AA、DA和UA的无酶电化学传感器的研究进展,对此类电化学传感器的今后发展做了展望。     

Applications of poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonic acid) transistors in chemical and biological sensors

The application of transistors based on poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonic acid) (PEDOT:PSS) in chemical and biological sensing is reviewed. These devices offer enormous potential for facile processing of small, portable, and inexpensive sensors ideally suited for point-of-care analysis. They can be used to detect a wide range of analytes for a variety of possible applications in fields such as health care (medical diagnostics), environmental monitoring (airborne chemicals, water contamination, etc.), and food industry (smart packaging). Organic transistors are excellent candidates to act as transducers because they have the ability to translate chemical and biological signals into electronic signals with high sensitivity. Furthermore, fuctionalization of PEDOT:PSS films with a chemical or biological receptor can lead to high specificity. The advantages of using PEDOT:PSS transistors are described, and applications are presented for sensing analytes in both gaseous and aqueous environments.     

Laser-induced Graphene in Facts,Numbers, and Notes in View of Electroanalytical Applications: A Review

In this review, laser-induced graphene (LIG) -based electrodes are discussed by covering such essential areas, as a characterization of LIG material properties necessary for electroanalysis, including data on LIG sheet resistance, wettability, spatial resolution, electrochemical characteristics, as well as correlations of “process” - “properties” - “electroanalytical characteristics”of LIG-electrodes. Moreover, typical and innovative LIG-based electrodes designs for electroanalytical applications, including combined multi-analyte multimodal wearable sensors, interdigitated electrodes, are shown. The essential data related to LIG in electroanalysis are summarized in tables. The authors also discussed recent LIG-based electroanalytical applications. Close attention has been paid to LIG glucose sensors and biosensors.     

Quantitative Chirality and Concentration Sensing of Alcohols,Diols, Hydroxy Acids,Amines and Amino Alcohols using Chlorophosphite Sensors in a Relay Assay

Analytical methods that allow simultaneous determination of the concentration and enantiomeric composition of small sample amounts and are also compatible with high-throughput multi-well plate technology have received increasing attention in recent years. We now introduce a new class of broadly useful small-molecule probes and a relay sensing strategy that together accomplish these tasks with five classes of compounds including the challenging group of mono-alcohols—a scope that stands out among previously reported UV, fluorescence, and CD assays. Several chlorophosphite probes and aniline indicators have been evaluated and used for on-the-fly CD/UV sensing following a continuous workflow. The wide application range of the readily available sensors is highlighted with almost 30 alcohols, diols, hydroxy acids, amines and amino alcohols, and the accuracy of the stereochemical analysis is showcased with samples covering a wide range of concentrations and enantiomeric ratios.     

Design of a Prussian Blue Analogue/Carbon Nanotube Thin‐Film Nanocomposite: Tailored Precursor Preparation,Synthesis, Characterization,and Application

Multi‐walled carbon nanotubes (MWCNTs) filled with different species of cobalt (metallic cobalt, cobalt oxide) were synthesized by a chemical vapor deposition method through cobaltocene pyrolysis. A systematic study was performed to correlate different experimental conditions with the structure and characteristics of the obtained material. Thin films of Co‐filled CNTs were deposited over conductive substrates through a liquid–liquid interfacial method and were used for cobalt hexacyanoferrate (CoHCFe) electrodeposition by an innovative route in which the Co species encapsulated in the CNTs were employed as reactants. The CNT/CoHCFe films were characterized by different spectroscopic, microscopic, and electrochemical techniques and presented high electrochemical stability in different media. The nanocomposites were applied as both an electrochemical sensor to H₂O₂ and a cathode for ion batteries and showed limits of detection at approximately 3.7 nmol L ^?1 and a capacity of 130 mAh g^?1 at a current density of 5 A g^?1.     

Electrochemical Impedance Spectroscopy in the Characterisation and Application of Modified Electrodes for Electrochemical Sensors and Biosensors

Electrochemical impedance spectroscopy is finding increasing use in electrochemical sensors and biosensors, both in their characterisation, including during successive phases of sensor construction, and in application as a quantitative determination technique. Much of the published work continues to make little use of all the information that can be furnished by full physical modelling and analysis of the impedance spectra, and thus does not throw more than a superficial light on the processes occurring. Analysis is often restricted to estimating values of charge transfer resistances without interpretation and ignoring other electrical equivalent circuit components. In this article, the important basics of electrochemical impedance for electrochemical sensors and biosensors are presented, focussing on the necessary electrical circuit elements. This is followed by examples of its use in characterisation and in electroanalytical applications, at the same time demonstrating how fuller use can be made of the information obtained from complete modelling and analysis of the data in the spectra, the values of the circuit components and their physical meaning. The future outlook for electrochemical impedance in the sensing field is discussed.     

Highly Selective Sensing Platform Utilizing Graphene Oxide and Multiwalled Carbon Nanotubes for the Sensitive Determination of Tramadol in the Presence of Co‐Formulated Drugs

Novel insights into the strategy of highly precise, carbon‐based electrochemical sensors are presented by exploring the excellent properties of graphene oxide (GO) and multiwalled carbon nanotube composites (GO‐MWCNTs/CPE) for the sensitive determination of tramadol hydrochloride (TRH). Cyclic voltammetry, differential pulse voltammetry, chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) scanning electron microscopy, and X‐ray diffraction (XRD) techniques were used to characterize the properties of the sensor. The linear response obtained for TRH using the GO‐MWCNTs/CPE was found to be over the range of 2.0x10⁻⁹ to 1.1x10⁻³ M with a good linearity and high correlation (0.9996). The limits of detection and quantification were found to be 1.50x10⁻¹⁰ M and 4.99 x 10⁻¹⁰ M, respectively. The proposed sensor was applied for determination of TRH in the presence of presence of co‐formulated drugs ketorolac tromethamine (KTM) and paracetamol (PAR). The sensor was shown to successfully apply to the determination of TRH in plasma as real samples. Satisfactory recoveries of TRH from samples clearly revealed that the proposed sensor can be applied into clinical analysis, quality control and a routine determination of drugs in pharmaceutical formulations.     

Scientific Importance of Water‐Processable PEDOT–PSS and Preparation,Challenge and New Application in Sensors of Its Film Electrode: A Review

In this review, PEDOT–PSS is mainly a commercially available PEDOT–PSS, which is a water‐dispersible form of the intrinsically conducting PEDOT doped with the water‐soluble PSS, including its derivatives, copolymers, analogs (PEDOT:PSSs), even their composites via the chemical or physical modification toward the structure of PEDOT and/or PSS. First, we will focus on discussing the scientific importance of PEDOT–PSS in conjunction with its extraordinary properties and broad multidisciplinary applications in organic/polymeric electronics and optoelectronics from the viewpoint of the historical development and the promising application of representative ECPs. Subsequently, versatile film‐forming techniques for the preparation of PEDOT–PSS film electrode were described in details, including common coating approaches and printing techniques, and many emerging preparative methods were mentioned. Then challenges (e.g., conductivity, stability in Water, adhesion to substrate electrode) of PEDOT–PSS film electrode for devices under the high humidity/watery circumstances, especially electrochemical devices are discussed. Fourth, we take PEDOT–PSS film electrode for a relatively new application in sensors as an example, mainly summarized advances in the development of various sensors based on PEDOT–PSSs and their composites in combination with its preparative methods and extraordinary properties. Finally, we give the outlook of PEDOT–PSS for possible applications with the emphasis on PEDOT–PSS film electrode for electrochemical devices, including sensors. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 55, 1121–1150     

Revealing the Chemical State of Palladium in Operating In2O3 Gas Sensors: Metallic Pd Enhances Sensing Response and Intermetallic InxPdy Compound Blocks It

The sensing response of metal oxides activated with noble metal nanoparticles is significantly influenced by changes to the chemical state of corresponding elements under operating conditions. Here, a PdO/rh-In₂O₃ consisting of PdO nanoparticles loaded onto rhombohedral In₂O₃ was studied as a gas sensor for H₂ gas (100–40000 ppm in an oxygen-free atmosphere) in the temperature range of 25–450 °C. The phase composition and chemical state of elements were examined by resistance measurements combined with synchrotron-based in situ X-ray diffraction and ex situ X-ray photoelectron spectroscopy. As found, PdO/rh-In₂O₃ undergoes a series of structural and chemical transformations during operation: from PdO to Pd/PdH_x and finally to the intermetallic In_xPd_y phase. The maximal sensing response (R_N2/R_H2) of ∼5 ⋅ 10⁷ towards 40000 ppm (4 vol %) H₂ at 70 °C is correlated with the formation of PdH_0.706/Pd. The In_xPd_y intermetallic compounds formed around 250 °C significantly decrease the sensing response.