Supramolecular analytical chemistry has emerged as a new discipline at the interface of supramolecular and analytical chemistry. It focuses on analytical applications of molecular recognition and self-assembly. One of the important outcomes of the supramolecular analytical chemistry is the understanding of molecular aspects of sensor design, synthesis and binding studies of sensors while using rigorous methods of analytical chemistry as a touchstone to verify the viability of the supramolecular aspects of the sensor design. This critical review provides a simplified version of the chemometric procedures involved in realizing a successful analytical experiment that utilizes cross-reactive optical sensor arrays, and summarizes the current research in this field. This review also shows several examples of use of described chemometric methods for evaluation of chemosensors and sensor arrays. Thus, this review is aimed mostly at the readers who want to test their newly-developed chemosensors in cross-reactive arrays (169 references).

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A practical approach to optical cross-reactive sensor arrays

A Practical Approach to Optical Cross-Reactive Sensor Arrays

A disposable preoxidation technique that dramatically improves the detection and identification of volatile organic compounds (VOCs) by a colorimetric sensor array is reported. Passing a vapor stream through a tube packed with chromic acid on silica immediately before the colorimetric sensor array substantially increases the sensitivity to less-reactive VOCs and improves the limits of detection (LODs) ~300-fold, permitting the detection, identification, and discrimination of 20 commonly found indoor VOC pollutants at both their immediately dangerous to life or health (IDLH) and permissible exposure limit (PEL) concentrations. The LODs of these pollutants were on average 1.4% of their respective PELs.

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Preoxidation for colorimetric sensor array detection of VOCs.

Rapid identification of both species and even specific strains of human pathogenic bacteria grown on standard agar has been achieved from the volatiles they produce using a disposable colorimetric sensor array in a Petri dish imaged with an inexpensive scanner. All 10 strains of bacteria tested, including Enterococcus faecalis and Staphylococcus aureus and their antibiotic-resistant forms, were identified with 98.8% accuracy within 10 h, a clinically important time frame. Furthermore, the colorimetric sensor arrays also proved useful as a simple research tool for the study of bacterial metabolism and as an easy method for the optimization of bacterial production of fine chemicals or other fermentation processes.

/pdf/rapid-identification-of-bacteria-with-a-disposable-334uq6dttp.pdf

Rapid Identification of Bacteria with a Disposable Colorimetric Sensing Array

A colorimetric sensor array for identification of toxic gases below permissible exposure limits

This paper presents a high dynamic range CMOS image sensor that utilizes a combined linear-logarithmic readout scheme with built-in linear-logarithmic switching point detection for scientific imaging applications. The proposed readout architecture adjusts each individual pixel to operate in either linear or logarithmic readout mode according to the input illumination level. This realizes direct high-throughput image reconstruction enabling a hybrid combination of linear and logarithmic pixel outputs in the same image frame without introducing complicated post-signal processing. A novel feature of fine-tuning the overall dynamic range and contrast of the output image is also achieved using this readout method. An image sensor chip consisting of a 16times16 7-T pixel array with n-well/p-sub photodiodes and the proposed readout architecture has been implemented in 0.5 mum CMOS technology. The sensor chip has been evaluated through both electrical and optical characterizations, demonstrating an overall dynamic range of 121 dB. As a proof of concept, scientific imaging results on clusters of nano particles (CoFe2O4) and optical fiber sensor are presented and discussed.

A High Dynamic Range CMOS Image Sensor for Scientific Imaging Applications

The design and implementation of a portable fluorescence-based vapor sensing system are described The system incorporates previously developed microsensor array technology into a compact, low-power device capable of collecting and delivering ambient vapor samples to the array while monitoring and recording the fluorescent responses of the sensors The sensors respond differentially when exposed to a sample vapor and, when processed using a support vector machine (SVM) pattern recognition algorithm, are shown to discriminate between three classes of petroleum distillates The system was characterized using sample vapors prepared under several different conditions in three sensing scenarios The first scenario demonstrates the basic operational capability of the device in the field by presenting high concentration vapors to the array The second scenario introduces the potential for a greater degree of variability in both sample vapor concentration and composition in an effort to emulate real-world sensing

Design, implementation, and field testing of a portable fluorescence-based vapor sensor.

This paper presents a novel CMOS image sensor with direct digital phase output for fluorescence lifetime imaging applications. The phase-shift between intensity modulated excitation signal and emitted fluorescence is extracted utilizing a zero-crossing detection algorithm as a time-domain delay signal. A Time-to-Digital Converter (TDC) is subsequently used to quantize the time delay into digital output. A prototype sensor chip consisting of 32×32 passive pixel array, row-parallel phase extraction circuitry, and a global TDC is fabricated in 65nm low-power CMOS technology. The chip occupies 4mm×4mm silicon area with 1.2mW power consumption. Extensive characterization and phase image reconstruction results demonstrate both high sensitivity and good linearity performance of the digital phase readout. The TDC features 110ps temporal resolution over 414μs dynamic range. The proposed imager architecture offers an attractive solution for developing low-cost, low-power, and highly-integrated fluorescence lifetime imaging devices.

A CMOS imager with digital phase readout for fluorescence lifetime imaging

Among other things, devices for use in fluorescence or luminescence lifetime imaging are described. The devices include integrated complementary metal-oxide semiconductor (CMOS) chips that include an imaging region and a time-to-digital converter. The imaging region includes a photodetector for receiving optical signals. The time-to-digital converter provides digital phase output based on the received optical signals.

Imaging fluorescence or luminescence lifetime

This paper presents an area-efficient and low-power current-mode logarithmic analog-to-digital converter (LADC) that can be potentially used for large-scale CMOS sensor array applications. The core of the proposed LADC consists of a novel analog functional block and a reference transistor working in the subthreshold region, which encodes the input sensor currents into logarithmically compressed voltage outputs. The LADC core has been implemented in standard 0.18 ?m CMOS process with a total area of 55 ?m × 55 ?m and a power consumption of less than 9.7 ?W. A 7-bit digital counter and an external discrete ramp generator, typically shared among all sensor unit cells in the future sensor array implementation, complete the LADC configuration. Measurement results have presented a dynamic range of 80 dB with 5 KS/s conversion rate. The proposed LADC is ideally suited for compact and low-power CMOS biomedical sensor arrays or CMOS image sensor applications.

Jian Guo

Papers

A High Dynamic Range CMOS Image Sensor for Scientific Imaging Applications

Design, implementation, and field testing of a portable fluorescence-based vapor sensor.

A CMOS imager with digital phase readout for fluorescence lifetime imaging

Imaging fluorescence or luminescence lifetime

An Area-Efficient and Low-Power Logarithmic A/D Converter for Current-Mode Sensor Array