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- LAPS (4)
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- hydrogen peroxide (3)
- tobacco mosaic virus (TMV) (3)
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- light-addressable potentiometric sensor (2)
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- MOS (1)
- Multianalyte detection (1)
- Negative impedance convertor (1)
- O2 plasma (1)
- Organic light-emitting diode display (1)
- Penicillin (1)
- Poly(allylamine hydrochloride) (1)
- Poly(d,l-lacticacid) (1)
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- Real-time monitoring (1)
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- Sn₃O₄ (1)
- Sterilisation process (1)
- TMV adsorption (1)
- Ta₂O₅ gate (1)
- XOR (1)
- actuator-sensor system (1)
- aminooctanethiol (1)
- annealing (1)
- artificial olfactory image (1)
- aseptic parameters (1)
- barium strontium titanate (1)
- bi-enzyme biosensor (1)
- biosensor (1)
- biosensors (1)
- calorimetric gas sensor (1)
- calorimetric gas sensor;hydrogen peroxide;wireless sensor system (1)
- capacitive EIS sensor (1)
- capacitive model (1)
- catalytic metal (1)
- chemical sensor (1)
- contactless conductivity sensor (1)
- control gate (1)
- detection of charged macromolecules (1)
- electrolyte-insulator semiconductor sensor (EIS) (1)
- electrolyte-insulator-semiconductor capacitors (1)
- electronic nose (1)
- endospores (1)
- enzymatic (bio)degradation (1)
- enzyme cascade (1)
- enzyme kinetics (1)
- enzyme-logic gate (1)
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- field-effect structure (1)
- gas sensor (1)
- gaseous hydrogen peroxide (1)
- glucose oxidase (GOx) (1)
- heavy metals (1)
- high-k material (1)
- horseradish peroxidase (HRP) (1)
- hydroxylation (1)
- immobilization (1)
- impedance spectroscopy (1)
- in-situ monitoring (1)
- lable-free detection (1)
- light-addressable electrode (1)
- light-addressing technologies (1)
- metal-oxide-semiconductor structure (1)
- microfluidics (1)
- multi-functional material (1)
- multi-sensing platform (1)
- multianalyte detection (1)
- nanobelts (1)
- nanoparticle coverage (1)
- novel photoexcitation method (1)
- on-chip integrated addressable EISCAP sensors (1)
- optical sensor setup (1)
- optical spore trapping (1)
- optical trapping (1)
- organosilanes (1)
- penicillinase (1)
- plant virus detection (1)
- plug-based microfluidic device (1)
- poly(d, l-lactic acid) (1)
- polystyrene sulfonate (1)
- scanned light pulse technique (1)
- silanization (1)
- spatial resolution (1)
- spore kill rate (1)
- sterilisation (1)
- sterility (1)
- sterilization (1)
- sterilization conditions (1)
- surface functionalization (1)
- temperature (1)
- tilted constant illumination (1)
- turnip vein clearing virus (TVCV) (1)
- urease (1)
- visualization (1)
Multi-enzyme immobilization onto a capacitive field-effect biosensor by nano-spotting technique is presented. The nano-spotting technique allows to immobilize different enzymes simultaneously on the sensor surface with high spatial resolution without additional photolithographical patterning. The amount of applied enzymatic cocktail on the sensor surface can be tailored. Capacitive electrolyte-insulator-semiconductor (EIS) field-effect sensors with Ta2O5 as pH-sensitive transducer layer have been chosen to immobilize the three different (pL droplets) enzymes penicillinase, urease, and glucose oxidase. Nano-spotting immobilization is compared to conventional drop-coating method by defining different geometrical layouts on the sensor surface (fully, half-, and quarter-spotted). The drop diameter is varying between 84 µm and 102 µm, depending on the number of applied drops (1 to 4) per spot. For multi-analyte detection, penicillinase and urease are simultaneously nano-spotted on the EIS sensor. Sensor characterization was performed by C/V (capacitance/voltage) and ConCap (constant capacitance) measurements. Average penicillin, glucose, and urea sensitivities for the spotted enzymes were 81.7 mV/dec, 40.5 mV/dec, and 68.9 mV/dec, respectively.
A wireless sensor system based on the industrial ZigBee standard for low-rate wireless networking was developed that enables real-time monitoring of gaseous H2O2 during the package sterilization in aseptic food processes. The sensor system consists of a remote unit connected to a calorimetric gas sensor, which was already established in former works, and an external base unit connected to a laptop computer. The remote unit was built up by an XBee radio frequency (RF) module for data communication and a programmable system-on-chip controller to read out the sensor signal and process the sensor data, whereas the base unit is a second XBee RF module. For the rapid H2O2 detection on various locations inside the package that has to be sterilized, a novel read-out strategy of the calorimetric gas sensor was established, wherein the sensor response is measured within the short sterilization time and correlated with the present H2O2 concentration. In an exemplary measurement application in an aseptic filling machinery, the suitability of the new, wireless sensor system was demonstrated, wherein the influence of the gas velocity on the H2O2 distribution inside a package was determined and verified with microbiological tests.
The LAPS (light-addressable potentiometric sensor) platform is one of the most attractive approaches for chemical and biological sensing with many applications ranging from pH and ion/analyte concentration measurements up to cell metabolism detection and chemical imaging. However, although it is generally accepted that LAPS measurements are spatially resolved, the light-addressability feature of LAPS devices has not been discussed in detail so far. In this work, an extended electrical equivalent-circuit model of the LAPS has been presented, which takes into account possible cross-talk effects due to the capacitive coupling of the non-illuminated region. A shunting effect of the non-illuminated area on the measured photocurrent and addressability of LAPS devices has been studied. It has been shown, that the measured photocurrent will be determined not only by the local interfacial potential in the illuminated region but also by possible interfacial potential changes in the non-illuminated region, yielding cross-talk effects. These findings were supported by the experimental investigations of a penicillin-sensitive multi-spot LAPS and a metal-insulator-semiconductor LAPS as model systems.
An amperometric biosensor using a substrate recycling principle was realized for the detection of low adrenaline concentrations (1 nM) by measurements in phosphate buffer and Ringer’s solution at pH 6.5 and pH 7.4, respectively. In proof-of-concept experiments, a Boolean logic-gate principle has been applied to develop a digital adrenaline biosensor based on an enzyme AND logic gate. The obtained results demonstrate that the developed digital biosensor is capable for a rapid qualitative determination of the presence/absence of adrenaline in a YES/NO statement. Such digital biosensor could be used in clinical diagnostics for the control of a correct insertion of a catheter in the adrenal veins during adrenal venous-sampling procedure.
Utilizing an appropriate enzyme immobilization strategy is crucial for designing enzyme-based biosensors. Plant virus-like particles represent ideal nanoscaffolds for an extremely dense and precise immobilization of enzymes, due to their regular shape, high surface-to-volume ratio and high density of surface binding sites. In the present work, tobacco mosaic virus (TMV) particles were applied for the co-immobilization of penicillinase and urease onto the gate surface of a field-effect electrolyte-insulator-semiconductor capacitor (EISCAP) with a p-Si-SiO₂-Ta₂O₅ layer structure for the sequential detection of penicillin and urea. The TMV-assisted bi-enzyme EISCAP biosensor exhibited a high urea and penicillin sensitivity of 54 and 85 mV/dec, respectively, in the concentration range of 0.1–3 mM. For comparison, the characteristics of single-enzyme EISCAP biosensors modified with TMV particles immobilized with either penicillinase or urease were also investigated. The surface morphology of the TMV-modified Ta₂O₅-gate was analyzed by scanning electron microscopy. Additionally, the bi-enzyme EISCAP was applied to mimic an XOR (Exclusive OR) enzyme logic gate.
Trace metal determination by dc resistance changes of microstructured thin gold film electrodes
(1999)
Using a cell-based gas biosensor for investigation of adverse effects of acetone vapors in vitro
(2013)
The chemical imaging sensor is a field-effect sensor which is able to visualize both the distribution of ions (in LAPS mode) and the distribution of impedance (in SPIM mode) inthe sample. In this study, a novel wound-healing assay is proposed, in which the chemical imaging sensor operated in SPIM mode is applied to monitor the defect of a cell layer brought into proximity of the sensing surface.A reduced impedance inside the defect, which was artificially formed ina cell layer, was successfully visualized in a photocurrent image.
Visualization of the recovery process of defects in a cultured cell layer by chemical imaging sensor
(2016)
The chemical imaging sensor is a field-effect sensor which is able to visualize both the distribution of ions (in LAPS mode) and the distribution of impedance (in SPIM mode) in the sample. In this study, a novel cell assay is proposed, in which the chemical imaging sensor operated in SPIM mode is applied to monitor the recovery of defects in a cell layer brought into proximity of the sensing surface. A reduced impedance at a defect formed artificially in a cell layer was successfully visualized in a photocurrent image. The cell layer was cultured over two weeks, during which the temporal change of the photocurrent distribution corresponding to the recovery of the defect was observed.