石墨烯在自供能传感系统中的应用

随着现代社会智能化的加速发展,传感系统中传感器的数量、密度和分布范围不断增加,传统的供能方式难以满足如此复杂多变的传感器供能需求,从周围环境中收集能量并转化为电能的自供能传感器件是解决这一难题的有效途径。石墨烯不仅具有优异的传感性能,而且在各种能源器件中有广泛的应用,这为基于石墨烯的自供能传感器件设计提供了便利。近年来,人们已经研究和发展了多种多样的石墨烯自供能传感器件。本文基于自供能器件的基本能量供给原理,包括电化学供能、光伏供能、摩擦电供能、水伏供能以及热电、压电、热释电等其它供能,分别介绍了石墨烯在自供能传感器件中的应用,并展望了基于石墨烯的自供能传感器件的未来发展、挑战和前景。     

酶生物燃料电池自供能传感器的研究现状及应用

在现代分析领域中,对于生物传感器的要求不断倾向于微型化和便捷化。基于酶型生物燃料电池的自供能传感器在检测目标物的同时可以提供能量,避免了外电源的使用,为生物传感器的微型化和便捷化发展提供了有效途径,日益成为人们关注的焦点。本文按照设计原理进行分类,对近五年内发展的基于酶型生物燃料电池的自供能传感器进行了综述,并展望了其今后的研究趋势和应用前景。     

Self-powered sensors

One of the problems associated with miniaturization and portability of sensors is the power supply. Power supplies, such as batteries, are difficult to miniaturize and require a sensor design that allows for easy replacement or recharging. This review describes the field of self-powered sensing, where the sensor itself provides the power for the sensing device. Most self-powered-sensing strategies employ either nuclear energy conversion or electrochemical energy conversion. Nuclear energy conversion is employed for radioisotope or nuclear reactor sensing. Electrochemical energy conversion is employed for chemical and biological sensing. This review details the common strategies for self-powered nuclear, chemical, and biological sensing and discusses the future of the technology.     

Different approaches for fabrication of low-cost electrochemical sensors

Electrochemistry combined with economical and sustainable platforms (such as paper) provides portable, affordable, robust, and user-friendly devices. In general, techniques, such as photolithography and sputtering, are excellent alternatives for producing these platforms. However, owing to the requirement of expensive and sophisticated instrumentation, as well as cleanroom facilities, these techniques have limited access. Thus, the search for easy to use and produce approaches have been reported, using consumables, including adhesives, carbon ink, graphite, pencil, office paper, paperboard, among others. In this sense, in this mini-review, we discuss various strategies explored to fabricate low-cost electrochemical sensors, including its main applications. Different manufacturing methods, such as screen and stencil printing, laser-scribing, and pencil drawing, will be discussed here, emphasizing the performance of the obtained devices, in addition to their advantages and disadvantages.     

3D-Printed Bionic Ear for Sound Identification and Localization Based on In Situ Polling of PVDF-TrFE Film

Bionic acoustic sensors are an indispensable part to realize interactions between humans and robotics. In this work, a PVDF-TrFE sensor array with multiple active pixels combined with a 3D-printed bionic ear model is prepared, which can accurately detect sounds with different frequencies and locate the sound source from different directions. The PVDF-TrFE sensor array can clearly identify the sound within 25 cm, and the error between the accepted sound frequency and the original input frequency is less than 0.001%. Through the algorithm analysis of the input signal, the location of the sound source can be immediately analyzed. Compared with other acoustic sensors, this sensor has the advantages of being self-powered, small size, and high flexibility, which holds great potential for bionic applications.     

Metallic impurity free carbon nanotube paste electrodes

Electrodes modified with carbon nanomaterials find wide ranging applications in electrochemistry such as in energy generation and storage through to applications in electroanalysis. A substantial limitation is the presence of metallic impurities which vary between batches and can produce erroneous results. Consequently we have explored the electrochemical properties of metallic impurity free carbon nanotube paste electrodes using potassium ferrocyanide and hydrogen peroxide as model compounds. In terms of the latter utilising cyclic voltammetry, a linear range from 0.75 to 3 mM with a limit of detection of 0.19 mM is possible using the electrochemical oxidation of hydrogen peroxide while using the electrochemical reduction of the target analyte, a linear range from 0.5 to 249 mM is possible with a detection limit of 0.43 mM.The ultra-small size of the carbon nanotubes and fabrication methodology result in a tightly bound carbon nanotube electrode surface which does not exhibit thin-layer behaviour resulting in highly reproducible electrodes with the %RSD found to be 5.5%. These analytical ranges, detection limits and reproducibility are technologically useful.The carbon nanotubes utilised are completely free from metallic impurities and do not require lengthy processing to remove impurities and consequently have no variation in the purity of the nanomaterial between batches as is commonly the case for other available carbon nanotube material. The impurity free nature of this nanomaterial allows for highly reproducible and intelligent sensors based on carbon nanotubes to be understood and realised for the first time.     

Applications of metal nanoparticles/metal-organic frameworks composites in sensing field

Metal nanoparticles (MNPs) possess size-dependent desirable electronic and optical properties while metal-organic frameworks (MOFs) have an edge over extremely large specific surface areas, homogeneous structure, high porosity and remarkable chemical stability. Their combination (MNPs/MOFs) is a novel nanomaterial with broad application prospect in sensing field. To improve performance in sensing applications, we have paid great attention to synergistic effects between the two compositions above. Because of the synergistic effects between MNPs and MOFs, sensors on the basis of MNPs/MOFs composites show significant sensing enhancement with respect to stability, selectivity and sensitivity. In this review, various applications for MNPs/MOFs composites in electrochemical sensing, fluorescent sensing, colorimetric sensing, surface-enhanced Raman scattering sensing and chemiluminescence/electrochemiluminescence sensing are focused and summarized. Besides, the synergistic interactions between MNPs and MOFs was investigated. Finally, based on theoretical information from the reports as well as experimental experience, this review offers the challenges and opportunities for future research on MNPs/MOFs composites.     

Nanomaterials and Analytical Chemistry

Abstract

Nanomaterials play an important role in the area of sensor technology. In fact the sensitivity and the signal‐to‐noise ratio of many chemical sensors are significantly improved using nanomaterials. They have allowed the introduction of many strategies in sensors and biosensor technology. Recently, catalytic nanomotors were used for drug delivery, showing an oriented motion into the cells when they are assembled using magnetic nanowires. In this review, detailed bibliographic references are presented concerning the assembling of nanomaterial‐based sensors, and a brief discussion about the potential health risk of nanoparticles will be also presented.     

Aptamer–nanoparticle complexes as powerful diagnostic and therapeutic tools

Correct diagnosis and successful therapy are extremely important to enjoy a healthy life when suffering from a disease. To achieve these aims, various cutting-edge technologies have been designed and fabricated to diagnose and treat specific diseases. Among these technologies, aptamer–nanomaterial hybrids have received considerable attention from scientists and doctors because they have numerous advantages over other methods, such as good biocompatibility, low immunogenicity and controllable selectivity. In particular, aptamers, oligonucleic acids or peptides that bind to a specific target molecule, are regarded as outstanding biomolecules. In this review, several screening techniques for aptamers, also called systematic evolution of ligands by exponential enrichment (SELEX) methods, are introduced, and diagnostic and therapeutic aptamer applications are also presented. Furthermore, we describe diverse aptamer–nanomaterial conjugate designs and their applications for diagnosis and therapy.     

Recent progress in nanomaterial-enhanced fluorescence polarization/anisotropy sensors

In this review, we summarize the number of scientific publications in the field of FP/FA sensor in recent five years, and introduce the recent progress of FP/FA sensor based on nanomaterial. The various analytical applications of FP/FA sensor based on nanomaterial are discussed. We also provide perspectives on the current challenges and future prospects in the promising field.     

Recent progress in nanomaterial-enhanced fluorescence polarization/anisotropy sensors

As a promising signaling transduction approach, fluorescence polarization (FP)/fluorescence anisotropy (FA), provides a powerful quantitative tool for the rotational motion of fluorescently labeled molecules in chemical or biological homogeneous systems. Unlike fluorescence intensity, FP/FA is almost independent the concentration or quantum of fluorophores, but they are highly dependent on the size or molecular weight of the molecules or materials attached to fluorophores. Recently, significant progress in FP/FA was made, due to the introduction of some nanomaterials as FP/FA enhancers. The detection sensitivity is thus greatly improved by using nanomaterials as FP/FA enhancers, and nanomaterial-based FP/FA is currently used successfully in immunoassay, and analysis of protein, nucleic acid, small molecule and metal ion. Nanomaterial-based FP/FA provides a new kind of strategy to design fluorescent sensors and establishes innovative analytical methods. In this review, we summarize the scientific publications in the field of FP/FA sensor in recent five years, and first introduce the recent progress of FP/FA sensor based on nanomaterial. Subsequently, the various analytical applications of FP/FA based on nanomaterial are discussed. Finally, we provide perspectives on the current challenges and future prospects in this promising field.     

Electrochemical sensors based on graphene materials

Single?Clayered graphene, emerging as a true two?Cdimensional nanomaterial, has tremendous potential for electrochemical catalysis and biosensing as a novel electrode material. Considering the excellent properties of graphene, such as large surface?Cto?Cvolume ratio, high conductivity and electron mobility at room temperature, low energy dynamics of electrons with atomic thickness, robust mechanical and flexibility, we give a general view of recent advances in electrochemical sensors based on graphene. We are highlighting here important applications of graphene and graphene nanocomposites, and the assay strategies in electrochemical sensors for DNA, proteins, neurotransmitters, phytohormones, pollutants, metal ions, gases, hydrogen peroxide, and in medical, enzymatic and immunosensors.

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.     

Electrochromic sensors: Innovative devices enabled by spectroelectrochemical methods

Electrochromic sensors are electrochemical devices exploiting colour changes as a means to simplify device construction and instrumentation requirements. Despite their advantages, electrochromic sensors have begun to emerge only recently. Mainly based on the works appeared in the literature over the past 2 years, we describe the construction and operation of these devices. A simple framework is proposed to understand and classify these devices more easily. This is based on the sensor architecture, their power source, and how information is displayed. Despite being new, electrochromic sensors are already demonstrated in a number of applications, mostly related to health and point-of-care devices.     

Application of MXene in Electrochemical Sensors: A Review

Electroanalysis has obtained considerable progress over the past few years, especially in the field of electrochemical sensors. Broadly speaking, electrochemical sensors include not only conventional electrochemical biosensors or non-biosensors, but also emerging electrochemiluminescence (ECL) sensors and photoelectrochemical (PEC) sensors which are both combined with optical methods. In addition, various electrochemical sensing devices have been developed for practical purposes, such as multiplexed simultaneous detection of disease-related biomarkers and non-invasive body fluid monitoring. For the further performance improvement of electrochemical sensors, material is crucial. Recent years, a kind of two-dimensional (2D) nanomaterial MXene containing transition metal carbides, nitrides and carbonitrides, with unique structural, mechanical, electronic, optical, and thermal properties, have attracted a lot of attention form analytical chemists, and widely applied in electrochemical sensors. Here, we reviewed electrochemical sensors based on MXene from Nov. 2014 (when the first work about electrochemical sensor based on MXene published) to Mar. 2021, dividing them into different types as electrochemical biosensors, electrochemical non-biosensors, electrochemiluminescence sensors, photoelectrochemical sensors and flexible sensors. We believe this review will be of help to those who want to design or develop electrochemical sensors based on MXene, hoping new inspirations could be sparked.     

Recent advances and applications in QDs-based sensors

As a unique nanomaterial, quantum dots (QDs) are not only applied in fluorescent labeling and biological imaging, but are also utilized in novel sensing systems. Because QDs have attractive optoelectronic characteristics, QD-based sensors present high sensitivity in detecting specific analytes in the chemical and biochemical fields. In this review, we describe the basic principles and different conjugation strategies in QD-based sensors. An overview of recent advances and various models of QD-sensing systems is also provided. Furthermore, perspectives for sensors based on QDs are discussed.     

Nanomaterial surface chemistry design for advancements in capillary electrophoresis modes

Tailored surface chemistry impacts nanomaterial function and stability in applications including in various capillary electrophoresis (CE) modes. Although colloidal nanoparticles were first integrated as colouring agents in artwork and pottery over 2000 years ago, recent developments in nanoparticle synthesis and surface modification increased their usefulness and incorporation in separation science. For instance, precise control of surface chemistry is critically important in modulating nanoparticle functionality and stability in dynamic environments. Herein, recent developments in nanomaterial pseudostationary and stationary phases will be summarized. First, nanomaterial core and surface chemistry compositions will be classified. Next, characterization methods will be described and related to nanomaterial function in various CE modes. Third, methods and implications of nanomaterial incorporation into CE will be discussed. Finally, nanoparticle-specific mechanisms likely involved in CE will be related to nanomaterial surface chemistry. Better understanding of surface chemistry will improve nanoparticle design for the integration into separation techniques.     

Ferroelectricity-Driven Self-Powered Ultraviolet Photodetection with Strong Polarization Sensitivity in a Two-Dimensional Halide Hybrid Perovskite

Polarization-sensitive ultraviolet (UV) photodetection is highly indispensable in military and civilian applications and has been demonstrated with various wide-band photodetectors. However, it still remains elusive to achieve the self-powered devices, which can be operated in the absence of external bias. Herein, for the first time, ferroelectricity-driven self-powered photodetection towards polarized UV light was successfully demonstrated in a 2D wide-band gap hybrid ferroelectric (BPA)₂PbBr₄ (BPA=3-bromopropylammonium) ( 1 ). We found that the prominent spontaneous polarization in 1 results in a bulk photovoltaic effect (BPVE) of 0.85 V, that independently drives photoexcited carriers separation and transport and thus supports self-powered ability. This self-powered detector shows strong polarization sensitivity to linearly polarized UV illumination with a polarization ratio up to 6.8, which is superior to that of previously reported UV-polarized photodetectors (ZnO, GaN, and GeS₂).     

Layer double hydroxides (LDHs)- based electrochemical and optical sensing assessments for quantification and identification of heavy metals in water and environment samples: A review of status and prospects

One of the most severe environmental problems is heavy metal contamination, putting the world's sustainability at risk. Much effort has been put into developing sensors that can be taken anywhere to detect the environmental effects of heavy metals. Sensitivity, selectivity, multiplexed detection ability, and mobility enhance significantly when nanoparticles and nanostructures are incorporated into sensors. LDHs (layered double hydroxides) have gotten much attention in analytical chemistry in recent years because of their benefits, including their large specific surface area, ease of synthesis, low cost, and high catalytic efficiency and biocompatibility. LDHs are often manufactured as nanomaterial composites or created with specialized three-dimensional structures depending on the application. However, in these settings, LDHs (as color indicators, extracting sorbents, and electrochemical sensing) are usually restricted. Upcoming signs of progress and development possibilities of LDHs in analytical chemistry are reviewed in this paper to assist overcome these problems. Furthermore, the approaches used in the design of LDHs, including structural aspects, are defined and assessed in preparation for future analytical applications. The latest advances in optical and electrochemical sensors to detect heavy metals are described in this review. The sorts and characteristics of LDHs will be explored first. We will then go into microelectrode (or nanoelectrode) arrays, nanoparticle-modified electrodes, and microfluidic optical and electrochemical sensing assays in detail. This paper also discusses design strategies for LDH-based nanostructured sensors and the advantages of using nanomaterials and nanostructures.