Refine
Year of publication
Document Type
- Article (95)
- Conference Proceeding (12)
- Part of a Book (2)
- Report (1)
Keywords
- Light-addressable potentiometric sensor (3)
- LAPS (2)
- light-addressable potentiometric sensor (2)
- Biosensor (1)
- Chemical images (1)
- Chemical imaging (1)
- Chemical imaging sensor (1)
- Chemical sensor (1)
- EIS capacitive sensor (1)
- Field-effect device (1)
- I3S 2005 (1)
- International Symposium on Sensor Science (1)
- Light-addressable Potentiometric Sensor (1)
- MOS (1)
- Negative impedance convertor (1)
- Organic light-emitting diode display (1)
- Potentiometry (1)
- Resonance-mode measurement (1)
- acetoin (1)
- acetoin reductase (1)
- actuator-sensor system (1)
- alcoholic beverages (1)
- artificial olfactory image (1)
- aseptic parameters (1)
- biosensors (1)
- capacitive field-effect sensors (1)
- catalytic metal (1)
- chemical sensor (1)
- electronic nose (1)
- enzymatic biosensor (1)
- enzyme kinetics (1)
- field-effect structure (1)
- gas sensor (1)
- gaseous hydrogen peroxide (1)
- light-addressable electrode (1)
- light-addressing technologies (1)
- metal-oxide-semiconductor structure (1)
- microfluidics (1)
- multi-sensing platform (1)
- novel photoexcitation method (1)
- penicillin (1)
- penicillinase (1)
- photoelectrochemistry (1)
- plug-based microfluidic device (1)
- scanned light pulse technique (1)
- spatial resolution (1)
- spore kill rate (1)
- sterility (1)
- tilted constant illumination (1)
- titanium dioxide photoanode (1)
- visualization (1)
To study chemical and biological processes, spatially resolved determination of the concentrations of one or more analyte species is of distinct interest. With a light-addressable potentiometric sensor (LAPS), chemical images can be created, which visualize the concentration distribution above the sensor plate. One important challenge is to achieve a good lateral resolution in order to detect events that take place in a small and limited region. LAPS utilizes a focused light spot to address the measurement region. By moving this light spot along the semiconductor sensor plate, the concentration distribution can be observed. In this study, we show that utilizing a pulse as light excitation instead of a traditionally used continuously modulated light excitation, the lateral resolution can be improved by a factor of 6 or more.
A capacitive electrolyte-insulator-semiconductor (EIS) field-effect biosensor for acetoin detection has been presented for the first time. The EIS sensor consists of a layer structure of Al/p-Si/SiO₂/Ta₂O₅/enzyme acetoin reductase. The enzyme, also referred to as butane-2,3-diol dehydrogenase from B. clausii DSM 8716T, has been recently characterized. The enzyme catalyzes the (R)-specific reduction of racemic acetoin to (R,R)- and meso-butane-2,3-diol, respectively. Two different enzyme immobilization strategies (cross-linking by using glutaraldehyde and adsorption) have been studied. Typical biosensor parameters such as optimal pH working range, sensitivity, hysteresis, linear concentration range and long-term stability have been examined by means of constant-capacitance (ConCap) mode measurements. Furthermore, preliminary experiments have been successfully carried out for the detection of acetoin in diluted white wine samples.
The chemical imaging sensor is a semiconductor-based chemical sensor capable of visualizing pH and ion distributions. The spatial resolution depends on the lateral diffusion of photocarriers generated by illumination of the semiconductor substrate. In this study, two types of optical setups, one based on a bundle of optical fibers and the other based on a binocular tube head, were developed to project a hybrid illumination of a modulated light beam and a ring-shaped constant illumination onto the sensor plate. An improved spatial resolution was realized by the ring-shaped constant illumination, which suppressed lateral diffusion of photocarriers by enhanced recombination due to the increased carrier concentration.
The light-addressable potentiometric sensor (LAPS) and scanning photo-induced impedance microscopy (SPIM) are two closely related methods to visualise the distributions of chemical species and impedance, respectively, at the interface between the sensing surface and the sample solution. They both have the same field-effect structure based on a semiconductor, which allows spatially resolved and label-free measurement of chemical species and impedance in the form of a photocurrent signal generated by a scanning light beam. In this article, the principles and various operation modes of LAPS and SPIM, functionalisation of the sensing surface for measuring various species, LAPS-based chemical imaging and high-resolution sensors based on silicon-on-sapphire substrates are described and discussed, focusing on their technical details and prospective applications.