Non-selective chemical sensors in analytical chemistry: from “electronic nose” to “electronic tongue”

Development, recent historical background and analytical applications of promising sensor instruments based on sensor arrays with data processing by pattern recognition methods have been described. Attention is paid to the “electronic tongue” based on an array of original non-specific (non-selective) potentiometric chemical sensors. Application results for integral qualitative analysis of beverages and for quantitative analysis of biological liquids and solutions, containing heavy metals are reported. Discriminating abilities and precision obtained allow to consider “electronic tongue” as a perspective analytical tool. Received: 17 July 1997 / Revised: 19 February 1998 / Accepted: 24 February 1998     

Chemical and biological sensors based on organic thin-film transistors

The application of organic thin-film transistors (OTFTs) to chemical and biological sensing is reviewed. This review covers transistors that are based on the modulation of current through thin organic semiconducting films, and includes both field-effect and electrochemical transistors. The advantages of using OTFTs as sensors (including high sensitivity and selectivity) are described, and results are presented for sensing analytes in both gaseous and aqueous environments. The primary emphasis is on the major developments in the field of OTFT sensing over the last 5–10 years, but some earlier work is discussed briefly to provide a foundation.     

Effect of morphology on organic thin film transistor sensors

This review provides a general introduction to organic field-effect transistors and their application as chemical sensors. Thin film transistor device performance is greatly affected by the molecular structure and morphology of the organic semiconductor layer. Various methods for organic semiconductor deposition are surveyed. Recent progress in the fabrication of organic thin film transistor sensors as well as the correlation between morphology and analyte response is discussed.     

Recent progress in silicon-based biologically sensitive field-effect devices

Biologically sensitive field-effect devices (BioFEDs) advantageously combine the electronic field-effect functionality with the (bio)chemical receptor's recognition ability for (bio)chemical sensing. In this review, basic and widely applied device concepts of silicon-based BioFEDs (ion-sensitive field-effect transistor, silicon nanowire transistor, electrolyte-insulator-semiconductor capacitor, and light-addressable potentiometric sensor) are presented, and recent progress (from 2019 to early 2021) is discussed. One of the main advantages of BioFEDs is the label-free sensing principle enabling them to detect a large variety of biomolecules and bioparticles by their intrinsic charge. The review encompasses applications of BioFEDs for the label-free electrical detection of clinically relevant protein biomarkers, DNA molecules and viruses, enzyme–substrate reactions as well as recording of the cell acidification rate (as an indicator of cellular metabolism) and the extracellular potential.     

Field-effect transistor chemical sensors of single nanoribbon of copper phthalocyanine

Copper phthalocyanine (CuPc) nanoribbon field-effect transistors were implemented as chemical sensors. They showed fast response and high reversibility in the detection of the tetrahydrofuran atmosphere at room temperature. The drain current of the field-effect transistor sensor decreased from 6.7 to 0.2 nA when the transistor was measured under the tetrahydrofuran atmosphere. The sensor was self-refreshable in a few minutes. These results demonstrate that the organic single crystalline nanoribbon transistors could effectively act as chemical sensors. Supported by the National Natural Science Foundation of China (Grant Nos. 20721061, 50725311, 60736004, 60771031), the Ministry of Science and Technology of China (Grant Nos. 2006CB806200, 2006CB932100), and Chinese Academy of Sciences     

The character of the response of ZnO and SnO<Subscript>2</Subscript> sensors modified with porphyrins to volatile organic compounds

The influence of the modification of the surface of ZnO and SnO₂ sensors with 5,10,15,20-tetraphenylporphyrin on the parameters of sensor response to high-volatility organic substances was analyzed. The organic substances used were ethanol, acetone, and benzene. The sensor response was characterized by specific sensitivity γ determined as the ratio between a change in the resistance of the sensitive sensor layer and the volume concentration of high-volatility organic compounds introduced into the system. The modification of the sensors with tetraphenylporphyrin caused changes in sensor response, including a change in the sign of the γ parameter, which was of importance for creating “electronic nose” sensor systems.     

Organic electronics—Silicon device design without semiconductor band theory

Before the invention of the transistor in the 1940s, semiconductors were used as detectors in radios in a device called a “cat’s whisker”. At that time their operation was completely mysterious. Only after the introduction of semiconductor band theory did it become clear that the “cat’s whisker” is a primitive example of a metal-semiconductor Schottky diode. Today organic materials are being investigated for their electronic properties. Such materials are especially attractive for lightweight, flexible, and low-cost solar cells and light emitting devices, as well as transistors and electrophotographic photoreceptors. Yet, even after 40 years of work and a large database, the physics and chemistry that determines the electronic properties of organic materials are not well understood. Practicing organic electronics is like attempting to do silicon device design without semiconductor band theory. It is the purpose of this paper to briefly summarize what is known about the electronic properties of organic materials from charge transport data. It will be shown that our understanding of the charge transport mechanism and the electronic properties of organic materials is at a rudimentary phase which is a limiting factor in applying these materials to practical devices, very similar to the “cat’s whisker” phase of inorganic semiconductor research.     

Phthalocyanines as Sensitive Materials for Chemical Sensors

This paper provides a review of phthalocyan- ines suitable for the development of chemical sensors. Phthalocyanines may be utilized for different types of chemical sensors, including in particular electronic conductance sensors [such as semiconductive, field-effect transistor (FET), solid-state ionic and capacitance sensors], mass-sensitive sensors utilizing a quartz crystal microbalance (QCM) and surface acoustic-wave (SAW) sensors, and optical sensors. The phthalocyanines used are discussed in terms of their physical and chemical properties, as well as their sensitivity, selectivity and reversibility towards the detection of NO₂ and organic solvent vapours. The interaction mechanism between phthalocyanine films and analyte molecules is also discussed.     

Biomimetic PLGA sensor: proof of principle and application

Abstract  

Spoilage of products can mainly be attributed to microorganisms which “live on the product”, i.e. which are able to utilize and/or metabolize components and/or molecules of the product. The objective of this work was to develop and optimize sensor prototypes indicating the quality of a product “in real time”, i.e. at the time the consumer is looking at the product. The design of the presented sensors relates to optical phenomena, for example anomalous absorption and remission of light. The crucial point of the sensor prototypes is a layer sensitive to the analyte, a polymer degradable by enzymes produced by the respective microorganisms. After incubation of the sensor setup with contaminated products, the lytic enzymes released from decaying cell material change the thickness of the polymer layer and generate a colour change visible by the naked eye. Production of the sensor prototypes is very simple and inexpensive and they might be successfully integrated into product packaging.     

核酸适体功能化的二维材料场效应晶体管传感器研究进展

二维材料场效应晶体管传感器具有可调的电学性质和高的灵敏度, 非常适合用于构建高性能的传感器, 应用于疾病诊断和环境监测等领域. 核酸适体是一种生物识别分子, 具有特异性强、 稳定性高等优势. 近年来, 核酸适体功能化的二维材料场效应晶体管传感器在医疗诊断和环境监测等领域取得了显著的研究进展. 本文综合评述了核酸适体功能化的二维材料场效应晶体管传感器的最新研究进展, 对场效应晶体管传感器的结构及传感原理进行了概括, 详细介绍了二维材料的制备方法以及核酸适体功能化器件的设计原理. 在此基础上, 对核酸适体功能化的二维材料场效应晶体管传感器在疾病诊断和环境监测领域的应用进展进行了概述, 讨论了核酸适体功能化的二维材料场效应晶体管传感器面临的一些问题和挑战, 对其发展前景进行了展望.     

Analytical characteristics and sensitivity mechanisms of electrolyte-insulator-semiconductor system-based chemical sensors—a critical review

Recent trends in research and development of electrolyte-insulator-semiconductor (EIS) field-effect chemical sensors (ion-selective field-effect transistors, light-addressable potentiometric sensors, capacitive EIS-sensors) with inorganic gate insulators (oxide, nitride and chalcogenide films) are reviewed. Physical properties of EIS systems and basic mechanisms of their chemical sensitivity are examined. Analytical characteristics and sensing mechanisms of EIS pH sensors with oxide and nitride films, as well as metal ions sensors with chalcogenide films, are critically discussed. Prospects of future research on EIS field-effect biosensors are briefly outlined.     

Recent trends in potentiometric sensor arrays--a review

Nowadays there exists a large variety of ion sensors based on polymeric or solid-state membranes that can be used in a sensor array format in many analytical applications. This review aims at providing a critical overview of the distinct approaches that were developed to build and use potentiometric sensor arrays based on different transduction principles, such as classical ion-selective electrodes (ISEs) with polymer or solid-state membranes, solid-contact electrodes (SCE) including coated wire electrodes (CWE), ion-sensitive field-effect transistors (ISFETs) and light addressable potentiometric sensors (LAPS). Analysing latest publications on potentiometric sensor arrays development and applications certain problems are outlined and trends are discussed.     

SIMS depth profiling of vertical p-channel Si-MOS transistor structures

SIMS depth profiling during O₂ ⁺ bombardment has been performed to analyse epitaxially grown Si p-n-p layers, which define the p-channel region in vertical Si-p MOS transistors, as well as to establish “on-chip” depth profiling of the functional vertical device. The SIMS detection limit of ³¹P in Si, phosphorus used as n-type dopant in the transistor, has been optimised as a function of the residual gas pressure in the SIMS analysis chamber and of the sputter erosion rate. We demonstrate that good vacuum during SIMS analysis combined with high erosion rates allows the simultaneous quantitative SIMS depth profiling of n- and p-type dopant concentrations in the vertical transistor. Small area “on-chip” SIMS depth profiling through the layered structure of Al-contact/TiSi₂/Si(p-n-p)/Si-substrate has been performed. Factors influencing the depth resolution during “on-chip” analysis of the transistor are discussed especially in terms of sputtering induced ripple formation at the erosion crater bottom, which has been imaged with atomic force microscopy. Received: 15 August 1996 / Revised: 17 January 1997 / Accepted: 21 January 1997     

Transistor-Based Work-Function Measurement of Metal–Organic Frameworks for Ultra-Low-Power,Rationally Designed Chemical Sensors

A classic challenge in chemical sensing is selectivity. Metal–organic frameworks (MOFs) are an exciting class of materials because they can be tuned for selective chemical adsorption. Adsorption events trigger work-function shifts, which can be detected with a chemical-sensitive field-effect transistor (power ≈microwatts). In this work, several case studies were used towards generalizing the sensing mechanism, ultimately towards our metal-centric hypothesis. HKUST-1 was used as a proof-of-principle humidity sensor. The response is thickness independent, meaning the response is surface localized. ZIF-8 is demonstrated to be an NO₂-sensing material, and the response is dominated by adsorption at metal sites. Finally, MFM-300(In) shows how standard hard–soft acid–base theory can be used to qualitatively predict sensor responses. This paper sets the groundwork for using the tunability of metal–organic frameworks for chemical sensing with distributed, scalable devices.     

Information Theory, the Shape Function, and the Hirshfeld Atom

Following the work of Nalewajski and Parr, there has been a surge of interest in the use of information theory to describe chemical bonding and chemical reactions. However, the measure of “information” used by Nalewajski and Parr is not any of the usual conventional entropies, chiefly because the electron density is not normalized to one. The consequences of this are discussed, and a solution is constructed using the shape function and an “entropy of mixing” term. The same revision, however, cannot be made when if the Tsallis entropy, instead of the Shannon form, is used. This serves to emphasize that the Hirshfeld atom is a very specific result, associated only with logarithmic measures of information. A less specific derivation due to Nalewajski provides one resolution to this quandary; this derivation is analyzed in detail.     

Multivariate statistical analysis of coastal sediment data

Multivariate statistical analysis of sediment data (information matrix 123 × 16) from the Gulf of Mexico, USA shows that the data structure is defined by four latent factors conditionally called “inorganic natural”, “inorganic anthropogenic”, “bioorganic” and “organic anthropogenic” explaining 39.24%, 23.17%, 10.77% and 10.67% of the total variance of the data system, respectively. The receptor model obtained by the application of the PCR approach makes it possible to apportion the contribution of each chemical component for the latent factor formation. A separation of the contribution of each chemical parameter is achieved within the frames of “natural” and “anthropogenic” origin of the respective heavy metal or organic matter to the sediment formation process. This is a new approach as compared to the traditional “one dimensional” search with a limited number of preliminary selected tracer components. The model suggested divides natural from anthropogenic influences and allows in this way each participant in the sediment formation process to be used as marker of either natural or anthropogenic effects. Received: 20 March 1999 / Revised: 1 June 1999 / Accepted: 3 June 1999     

Multivariate statistical analysis of coastal sediment data

Multivariate statistical analysis of sediment data (information matrix 123 × 16) from the Gulf of Mexico, USA shows that the data structure is defined by four latent factors conditionally called “inorganic natural”, “inorganic anthropogenic”, “bioorganic” and “organic anthropogenic” explaining 39.24%, 23.17%, 10.77% and 10.67% of the total variance of the data system, respectively. The receptor model obtained by the application of the PCR approach makes it possible to apportion the contribution of each chemical component for the latent factor formation. A separation of the contribution of each chemical parameter is achieved within the frames of “natural” and “anthropogenic” origin of the respective heavy metal or organic matter to the sediment formation process. This is a new approach as compared to the traditional “one dimensional” search with a limited number of preliminary selected tracer components. The model suggested divides natural from anthropogenic influences and allows in this way each participant in the sediment formation process to be used as marker of either natural or anthropogenic effects. Received: 20 March 1999 / Revised: 1 June 1999 / Accepted: 3 June 1999     

An advanced multivariate statistical approach to study coastal sediment data

The present paper deals with the application of classical and fuzzy principal components analysis to a large data set from coastal sediment analysis. Altogether 126 sampling sites from the Atlantic Coast of the USA are considered and at each site 16 chemical parameters are measured. It is found that four latent factors are responsible for the data structure (“natural”, “anthropogenic”, “bioorganic”, and “organic anthropogenic”). Additionally, estimating the scatter plots for factor scores revealed the similarity between the sampling sites. Geographical and urban factors are found to contribute to the sediment chemical composition. It is shown that the use of fuzzy PCA helps for better data interpretation especially in case of outliers.     

电位无标型糖化血红蛋白免疫微传感器

研制了基于标准CMOS工艺和微加工技术的电位无标型免疫微传感器,可实现糖化血红蛋白浓度与血红蛋白浓度的简便检测。该微传感器包括含有信号读出电路的场效应型微传感集成芯片和一次性测试试条。微传感集成芯片由本实验室设计并经新加坡Chartered半导体公司流片制备。一次性测试试条采用微加工技术制备于柔性塑料片上,包括敏感电极阵列和三维微结构测量池。基于自组装单层膜并引入纳米金颗粒的方法,在测试试条电极表面固定抗体。采用循环伏安法和交流阻抗法对电极表面的修饰过程进行了测试和分析。该传感器对糖化血红蛋白和血红蛋白检测的线性范围分别为4～24mg/L和60～180mg/L。