Conventional approaches to chemical sensors have
traditionally made use of a “lock-and-key” design,
wherein a specific receptor is synthesized in order to
strongly and highly selectively bind the analyte of
interest.1-6 A related approach involves exploiting a
general physicochemical effect selectively toward a
single analyte, such as the use of the ionic effect in
the construction of a pH electrode. In the first
approach, selectivity is achieved through recognition
of the analyte at the receptor site, and in the second,
selectivity is achieved through the transduction
process in which the method of detection dictates
which species are sensed. Such approaches are appropriate
when a specific target compound is to be
identified in the presence of controlled backgrounds
and interferences. However, this type of approach
requires the synthesis of a separate, highly selective
sensor for each analyte to be detected. In addition,
this type of approach is not particularly useful for
analyzing, classifying, or assigning human value
judgments to the composition of complex vapor
mixtures such as perfumes, beers, foods, mixtures of
solvents, etc.

/pdf/cross-reactive-chemical-sensor-arrays-38dz1buu0b.pdf

Cross-reactive chemical sensor arrays.

http://cau.ac.kr/~jjang14/BioMEMS/Bashir_ADDR_Reviews_BioMEMS_2004.pdf

BioMEMS: state-of-the-art in detection, opportunities and prospects

A currently emerging approach enables more widespread monitoring of health parameters in disease prevention and biomarker monitoring. Miniaturisation provides the means for the production of small, fast and easy-to-operate devices for reduced-cost healthcare testing at the point-of-care (POC) or even for household use. A critical overview is given on the present state and requirements of POC testing, on µTAS elements suited for implementation in future µTAS devices for POC testing and µTAS systems for the determination of clinical parameters.

Trends in miniaturized total analysis systems for point-of-care testing in clinical chemistry

Simultaneous electrochemical detection of As(III), Hg(II), and Cu(II) using a highly sensitive platform based on gold nanoelectrode ensembles (GNEEs) is described. GNEEs were grown by colloidal chemical approach on thiol-functionalized sol—gel derived three-dimensional silicate network preassembled on a polycrystalline gold (Au) electrode. GNEEs on the silicate network have been characterized by field emission scanning electron microscopy, X-ray diffraction, diffuse reflectance spectroscopy, and electrochemical measurements. Square wave anodic stripping voltammetry (SWASV) has been used for the detection of As(III) and Hg(II) without any interference from Cu(II) at the potentials of 0.06 and 0.53 V, respectively. The GNEE electrode is highly sensitive, and it shows linear response for As(III) and Hg(II) up to 15 ppb. The detection limit (signal-to-noise ratio = 4) of the GNEE electrode toward As(III) and Hg(II) is 0.02 ppb, which is well below the guideline value given by the World Health Organization (WH...

https://pubs.acs.org/doi/pdf/10.1021/ac8009214

Gold Nanoelectrode Ensembles for the Simultaneous Electrochemical Detection of Ultratrace Arsenic, Mercury, and Copper

Demanded by modern medical diagnosis, advances in microfabrication technology have led to the development of fast, sensitive and selective electrochemical sensors for clinic analysis. This review addresses the principles behind electrochemical sensor design and fabrication, and introduces recent progress in the application of electrochemical sensors to analysis of clinical chemicals such as blood gases, electrolytes, metabolites, DNA and antibodies, including basic and applied research. Miniaturized commercial electrochemical biosensors will form the basis of inexpensive and easy to use devices for acquiring chemical information to bring sophisticated analytical capabilities to the non-specialist and general public alike in the future.

/pdf/electrochemical-sensors-for-clinic-analysis-4s2fupmy7q.pdf

Electrochemical Sensors for Clinic Analysis.

A modular voltammetric multichannel detection system has been developed for use in flow analysis. Two different types of multichannel potentiostats, an adjustable and a ground-fixed potentiostat, are realized. Both types work with up to sixteen independent working electrodes at one chip electrode array and are controlled through a personal computer and a microcontroller. Simultaneous difference pulse and cyclic voltammetric procedures are realized. Platinum thin-film array electrodes have been arranged on silicon wafers as pairs of interdigitated microband electrodes (interdigitated array electrodes; IDA) with an interelectrode gap in the submicrometer range. Furthermore the multichannel electrodes in a flow system were used to characterize the highly sensitive flow profiles and flow rate measurements using redox mediators. A brief description of applying the multichannel device for ‘window’ stripping of heavy metals is given.

Voltammetric multichannel measurements using silicon fabricated microelectrode arrays

The combination of electrochemical transducers made in silion technology with chemical and biochemical components has been used to manufacture miniaturized sensor structures. Three different types of sensors have been developed and optimized for practical use: (i) an ion-selective sensor, (ii) a glucose enzyme sensor, (iii) a redox-amplifying sensor for immunosensing. The immunodetection based on the redox recycling of mediator molecules is shown for low and high molecular weight analytes. The sensors have been integrated with miniaturized fluidic components and combined with sensor-related electronics and a common microcontroller.

Microbiosensors using electrodes made in Si-technology.

The use of platinum-and gold-ultramicroelectrode arrays for heavy metal analysis is described. The noble metal microelectrodes are structured with standard silicon technologies. The geometry of the electrode array is varied and optimized in regard to the microelectrode characteristic. Mercury film formation and–dissolution on platinum microelectrode arrays is characterized and compared with iridium electrodes of the same geometry. Gold microelectrode arrays are shown to be useful for mercury detection. The repeated use of the sensors has been studied. Optimizing the electrode gemoetry and the stripping procedure results in detection limits down to the ng/L range.

Highly sensitive heavy metal analysis on platinum- and gold-ultramicroelectrode arrays

The performance of miniaturized potentiometric cells, with multilayer, planar ion-selective sensors in aqueous electrolyte solutions, human serum, urine, and whole blood, is presented. The basic steps of the fabrication with silicon technology are summarized. The effect of the contact surface between the internal reference system and the ion-sensitive membrane on the analytical characteristics of potassium- and calcium-sensitive sensors is studied. Silicone rubber-, high molecular weight PVC-, carboxylated PVC and aliphatic polyurethane (Tecoflex)-based solvent polymeric membranes were dispensed into anisotropically etched wells on silicon wafers, and the resulted planar sensors were tested in terms of their ion sensitivity (slopes of the cell voltage−pK or pCa calibration curves), long-term stability, and reproducibility. For the assay of potassium in whole blood, the miniaturized potentiometric cell was built in a flow-through manifold. To achieve the required precision, the flow conditions were optimiz...

Miniaturized Ion-Selective Chip Electrode for Sensor Application

An effective anodic-stripping method for the simultaneous detection of trace metals is described. For this purpose a sensor array consisting of three thin-film noble-metal microelectrode arrays made in silicon technology is designed. The use of a home-made multipotentiostat allows parallel control of different potential-time regimes for each electrode array. The trace metal are preconcentrated on the amalgamized electrodes by applying the optimal potential for the respective metal. After the deposition period, for every electrode a small potential window, specifically selected for the deposited metal, is scanned using differential pulse voltammetry (dpv). Thus only one metal is detected on each electrode. This stripping regime ensures a short measuring time and simplifies the evaluation of the results. Furthermore, errors resulting from intermetallic interactions in the amalgam layer are reduced.

Albrecht Uhlig

Papers

Voltammetric multichannel measurements using silicon fabricated microelectrode arrays

Microbiosensors using electrodes made in Si-technology.

Highly sensitive heavy metal analysis on platinum- and gold-ultramicroelectrode arrays

Miniaturized Ion-Selective Chip Electrode for Sensor Application

Chip-array electrodes for simultaneous stripping analysis of trace metals