Refine
Year of publication
Document Type
- Article (462)
- Conference Proceeding (50)
- Part of a Book (9)
- Book (2)
- Other (2)
- Report (1)
Language
- English (475)
- German (50)
- Multiple languages (1)
Keywords
- Biosensor (5)
- Graduiertentagung (4)
- LAPS (3)
- Label-free detection (3)
- Light-addressable potentiometric sensor (3)
- biosensors (3)
- capacitive field-effect sensor (3)
- field-effect sensor (3)
- hydrogen peroxide (3)
- tobacco mosaic virus (TMV) (3)
- Bacillus atrophaeus (2)
- Calorimetric gas sensor (2)
- Capacitive field-effect sensor (2)
- Hydrogen peroxide (2)
- Raman spectroscopy (2)
- Tobacco mosaic virus (TMV) (2)
- acetoin (2)
- capacitive field-effect sensors (2)
- gold nanoparticles (2)
- light-addressable potentiometric sensor (2)
- penicillinase (2)
- sterilisation (2)
- (Bio)degradation (1)
- Aachen / Fachhochschule Aachen (1)
- Bacillus atrophaeus spores (1)
- Bio-Sensors (1)
- Bioabsorbable (1)
- Biosensorik (1)
- CNOT (1)
- Capacitive field-effect (1)
- Capacitive model (1)
- Chemical images (1)
- Chemical imaging (1)
- Chemical imaging sensor (1)
- Chemical sensor (1)
- Coat protein (1)
- C–V method (1)
- DNA biosensor (1)
- DPA (dipicolinic acid) (1)
- Dehydrogenase (1)
- Diaphorase (1)
- EIS capacitive sensor (1)
- Electrolyte–insulator–semiconductor (1)
- Enzymatic biosensor (1)
- Enzyme coverage (1)
- Enzyme logic gate (1)
- Enzyme nanocarrier (1)
- Field effect (1)
- Field-effect biosensor (1)
- Field-effect device (1)
- Field-effect sensor (1)
- Gas sensor (1)
- Glucose biosensor (1)
- Glucose oxidase (1)
- Gold nanoparticles (1)
- Graduate symposium (1)
- Graduierter (1)
- Heavy metal detection (1)
- ISFET (1)
- Impedance spectroscopy (1)
- Layer-by-layer adsorption (1)
- LbL films (1)
- MOS (1)
- Multi-sensor system (1)
- Multianalyte detection (1)
- Multicell (1)
- Multiplexing (1)
- Nano Materials (1)
- Nanomaterial (1)
- Nanostructuring (1)
- Nanotechnologie (1)
- Negative impedance convertor (1)
- O2 plasma (1)
- Organic light-emitting diode display (1)
- Penicillin (1)
- Plant virus (1)
- Poly(allylamine hydrochloride) (1)
- Poly(d,l-lacticacid) (1)
- Polyimide (1)
- Polylactide acid (1)
- Potentiometry (1)
- Promotionsstudium (1)
- Real-time monitoring (1)
- Resistive temperature detector (1)
- Resonance-mode measurement (1)
- Silk fibroin (1)
- Simultaneous determination (1)
- Sn₃O₄ (1)
- Sterilisation process (1)
- TMV adsorption (1)
- Ta₂O₅ gate (1)
- Tobacco mosaic virus (1)
- Wafer (1)
- XOR (1)
- Zeta potential (1)
- acetoin reductase (1)
- actuator-sensor system (1)
- alcoholic beverages (1)
- aminooctanethiol (1)
- amperometric biosensors (1)
- annealing (1)
- artificial olfactory image (1)
- aseptic parameters (1)
- atomic layer deposition (1)
- bi-enzyme biosensor (1)
- bioburdens (1)
- biocompatible (1)
- biocompatible materials (1)
- biodegradabl (1)
- biodegradable electronic devices (1)
- biosensor (1)
- calorimetric gas sensor (1)
- calorimetric gas sensor;hydrogen peroxide;wireless sensor system (1)
- capacitive EIS sensor (1)
- capacitive electrolyte–insulator–semiconductor sensors (1)
- capacitive field-effect biosensor (1)
- capacitive model (1)
- capillary micro-droplet cell (1)
- carbon electrodes (1)
- catalytic decomposition (1)
- catalytic metal (1)
- chemical sensor (1)
- control gate (1)
- detection of charged macromolecules (1)
- electrolyte-insulator semiconductor sensor (EIS) (1)
- electrolyte-insulator-semiconductor capacitors (1)
- electronic nose (1)
- encapsulation materials (1)
- endospores (1)
- enzymatic biosensor (1)
- enzyme cascade (1)
- enzyme immobilization (1)
- enzyme kinetics (1)
- enzyme-logic gate (1)
- equivalent circuit (1)
- fibroin (1)
- field-effect structure (1)
- gas sensor (1)
- gaseous hydrogen peroxide (1)
- glucose (1)
- glucose oxidase (GOx) (1)
- graphene oxide (1)
- heavy metals (1)
- horseradish peroxidase (HRP) (1)
- hydroxylation (1)
- immobilization (1)
- layer expansion (1)
- layer-by-layer technique (1)
- light-addressable electrode (1)
- light-addressing technologies (1)
- metal-oxide-semiconductor structure (1)
- microfluidics (1)
- multi-sensing platform (1)
- multianalyte detection (1)
- nanobelts (1)
- nanomaterials (1)
- nanoparticle coverage (1)
- on-chip integrated addressable EISCAP sensors (1)
- optical sensor setup (1)
- optical spore trapping (1)
- optical trapping (1)
- organic PVC membranes (1)
- organosilanes (1)
- pH sensors (1)
- pattern-size reduction (1)
- penicillin (1)
- photoelectrochemistry (1)
- plant virus detection (1)
- plug-based microfluidic device (1)
- polyaniline (1)
- polystyrene sulfonate (1)
- scanned light pulse technique (1)
- self-aligned patterning (1)
- silanization (1)
- spore kill rate (1)
- sterility (1)
- sterility tests (1)
- sterilization (1)
- sterilization conditions (1)
- sterilization efficacy (1)
- sterilization methods (1)
- surface functionalization (1)
- temperature (1)
- thin-film microsensors (1)
- titanium dioxide photoanode (1)
- turnip vein clearing virus (TVCV) (1)
- ultrathin gate insulators (1)
- urease (1)
- validation methods (1)
- visualization (1)
- wafer-level testing (1)
Institute
- INB - Institut für Nano- und Biotechnologien (526) (remove)
The light-addressable potentiometric sensor (LAPS) is a semiconductor-based potentiometric sensor using a light probe with an ability of detecting the concentration of biochemical species in a spatially resolved manner. As an important biomedical sensor, research has been conducted to improve its performance, for instance, to realize high-speed measurement. In this work, the idea of facilitating the device-level simulation, instead of using an equivalent-circuit model, is presented for detailed analysis and optimization of the performance of the LAPS. Both carrier distribution and photocurrent response have been simulated to provide new insight into both amplitude-mode and phase-mode operations of the LAPS. Various device parameters can be examined to effectively design and optimize the LAPS structures and setups for enhanced performance.
As a semiconductor-based electrochemical sensor, the light-addressable potentiometric sensor (LAPS) can realize two dimensional visualization of (bio-)chemical reactions at the sensor surface addressed by localized illumination. Thanks to this imaging capability, various applications in biochemical and biomedical fields are expected, for which the spatial resolution is critically significant. In this study, therefore, the spatial resolution of the LAPS was investigated in detail based on the device simulation. By calculating the spatiotemporal change of the distributions of electrons and holes inside the semiconductor layer in response to a modulated illumination, the photocurrent response as well as the spatial resolution was obtained as a function of various parameters such as the thickness of the Si substrate, the doping concentration, the wavelength and the intensity of illumination.
The simulation results verified that both thinning the semiconductor substrate and increasing the doping concentration could improve the spatial resolution, which were in good agreement with known experimental results and theoretical analysis. More importantly, new findings of interests were also obtained. As for the dependence on the wavelength of illumination, it was found that the known dependence was not always the case. When the Si substrate was thick, a longer wavelength resulted in a higher spatial resolution which was known by experiments. When the Si substrate was thin, however, a longer wavelength of light resulted in a lower spatial resolution. This finding was explained as an effect of raised concentration of carriers, which reduced the thickness of the space charge region.
The device simulation was found to be helpful to understand the relationship between the spatial resolution and device parameters, to understand the physics behind it, and to optimize the device structure and measurement conditions for realizing higher performance of chemical imaging systems.
A novel photoexcitation method for the light-addressable potentiometric sensor (LAPS) is proposed to achieve a higher spatial resolution of chemical images. The proposed method employs a combined light source that consists of a modulated light probe, which generates the alternating photocurrent signal, and a ring of constant illumination surrounding it. The constant illumination generates a sheath of carriers with increased concentration which suppresses the spread of photocarriers by enhanced recombination. A device simulation was carried out to verify the effect of constant illumination on the spatial resolution, which demonstrated that a higher spatial resolution can be obtained.
Bonding of polymer-based microfluidics to polymer substrates still poses a challenge for Lab-On-a-Chip applications. Especially, when sensing elements are incorporated, patterned deposition of adhesives with curing at ambient conditions is required. Here, we demonstrate a fabrication method for fully printed microfluidic systems with sensing elements using inkjet and stereolithographic 3D-printing.
We present a sensor concept based on copper(II)oxide (CuO) nanofibres for the detection of hydrogen peroxide (H2O2) vapour in the percent per volume (% v/v) range. The fibres were produced by using the electrospinning technique. To avoid water condensation in the pores, the fibres were initially modified by an exposure to H2S to get an enclosed surface. By a thermal treatment at 350 °C the fibres were oxidised back to CuO. Thereby, the visible pores disappear which was verified by SEM analysis. The fibres show a decrease of resistance with increasing H2O2 concentration which is due to the fact that hydrogen peroxide is an oxidising gas and CuO a p-type semiconductor. The sensor shows a change of resistance within the minute range to the exposure until the maximum concentration of 6.9% v/v H2O2. At operating temperatures below 450 °C the corresponding sensor response to a concentration of 4.1% v/v increases. The sensor shows a good reproducibility of the signal at different measurements. CuO seems to be a suitable candidate for the detection of H2O2 vapour at high concentrations.
Resistance behaviour of the sensor under exposure to H2O2 vapours between 2.3 and 6.9% v/v at an operating temperature of 450 °C.
A graphene-functionalized carbon fiber electrode was modified with adsorbed polyethylenimine to introduce amino functionalities and then with trigonelline and 4-carboxyphenylboronic acid covalently bound to the amino groups. The trigonelline species containing quarterized pyridine groups produced positive charge on the electrode surface regardless of the pH value, while the phenylboronic acid species were neutral below pH 8 and negatively charged above pH 9 (note that their pKa=8.4). The total charge on the monolayer-modified electrode was positive at the neutral pH and negative at pH > 9. Note that 4-carboxyphenylboronic acid was attached to the electrode surface in molar excess to trigonelline, thus allowing the negative charge to dominate on the electrode surface at basic pH. Negatively charged fluorescent dye-labeled insulin (insulin-FITC) was loaded on the modified electrode surface at pH 7.0 due to its electrostatic attraction to the positively charged interface. The local pH in close vicinity to the electrode surface was increased to ca. 9–10 due to consumption of H+ ions upon electrochemical reduction of oxygen proceeding at the potential of −1.0 V (vs. Ag/AgCl) applied on the modified electrode. The process resulted in recharging of the electrode surface to the negative value due to the formation of the negative charge on the phenylboronic acid groups, thus resulting in the electrostatic repulsion of insulin-FITC and stimulating its release from the electrode surface. The insulin release was characterized by fluorescence spectroscopy (using the FITC-labeled insulin), by electrochemical measurements on an iridium oxide, IrOx, electrode and by mass spectrometry. The graphene-functionalized carbon fiber electrode demonstrated significant advantages in the signal-stimulated insulin release comparing with the carbon fiber electrode without the graphene species.
An enzyme-based reversible Controlled NOT (CNOT) logic gate operating on a semiconductor transducer
(2017)
An enzyme-based biocatalytic system mimicking operation of a logically reversible Controlled NOT (CNOT) gate has been interfaced with semiconductor electronic transducers. Electrolyte–insulator–semiconductor (EIS) structures have been used to transduce chemical changes produced by the enzyme system to an electronically readable capacitive output signal using field-effect features of the EIS device. Two enzymes, urease and esterase, were immobilized on the insulating interface of EIS structure producing local pH changes performing XOR logic operation controlled by various combinations of the input signals represented by urea and ethyl butyrate. Another EIS transducer was functionalized with esterase only, thus performing Identity (ID) logic operation for the ethyl butyrate input. Both semiconductor devices assembled in parallel operated as a logically reversible CNOT gate. The present system, despite its simplicity, demonstrated for the first time logically reversible function of the enzyme system transduced electronically with the semiconductor devices. The biomolecular realization of a CNOT gate interfaced with semiconductors is promising for integration into complex biomolecular networks and future biosensor/biomedical applications.
Multi-parameter detection for supporting monitoring and control of biogas processes in agriculture
(2014)
High-k perovskite oxide of barium strontium titanate (BST) represents a very attractive multi-functional transducer material for the development of (bio-)chemical sensors. In this work, a Si-based sensor chip containing Pt interdigitated electrodes covered with a thin BST layer (485 nm) has been developed for multi-parameter chemical sensing. The chip has been applied for the contactless measurement of the electrolyte conductivity, the detection of adsorbed charged macromolecules (positively charged polyelectrolytes of polyethylenimine) and the concentration of hydrogen peroxide (H2O2) vapor. The experimental results of functional testing of individual sensors are presented. The mechanism of the BST sensitivity to charged polyelectrolytes and H2O2 vapor has been proposed and discussed.
Chemische Sensoren mit Bariumstrontiumtitanat als funktionelle Schicht zur Multiparameterdetektion
(2013)
It is well known that biochemical and biotechnological processes are strongly dependent and affected by a variety of physico-chemical parameters such as pH value, temperature, pressure and electrolyte conductivity. Therefore, these quantities have to be monitored or controlled in order to guarantee a stable process operation, optimization and high yield. In this work, a sensor chip for the multiparameter detection of three physico-chemical parameters such as electrolyte conductivity, pH and temperature is realized using barium strontium titanate (BST) as multipurpose material. The chip integrates a capacitively coupled four-electrode electrolyte-conductivity sensor, a capacitive field-effect pH sensor and a thin-film Pt-temperature sensor. Due to the multifunctional properties of BST, it is utilized as final outermost coating layer of the processed sensor chip and serves as passivation and protection layer as well as pH-sensitive transducer material at the same time. The results of testing of the individual sensors of the developed multiparameter sensor chip are presented. In addition, a quasi-simultaneous multiparameter characterization of the sensor chip in buffer solutions with different pH value and electrolyte conductivity is performed. To study the sensor behavior and the suitability of BST as multifunctional material under harsh environmental conditions, the sensor chip was exemplarily tested in a biogas digestate.
Real-time and reliable monitoring of the biogas process is crucial for a stable and efficient operation of biogas production in order to avoid digester breakdowns. The concentration of dissolved hydrogen (H₂) represents one of the key parameters for biogas process control. In this work, a one-chip integrated combined amperometric/field-effect sensor for monitoring the dissolved H₂ concentration has been developed for biogas applications. The combination of two different transducer principles might allow a more accurate and reliable measurement of dissolved H₂ as an early warning indicator of digester failures. The feasibility of the approach has been demonstrated by simultaneous amperometric/field-effect measurements of dissolved H₂ concentrations in electrolyte solutions. Both, the amperometric and the field-effect transducer show a linear response behaviour in the H₂ concentration range from 0.1 to 3% (v/v) with a slope of 198.4 ± 13.7 nA/% (v/v) and 14.9 ± 0.5 mV/% (v/v), respectively.
Living cells are complex biological systems transforming metabolites taken up from the surrounding medium. Monitoring the responses of such cells to certain substrate concentrations is a challenging task and offers possibilities to gain insight into the vitality of a community influenced by the growth environment. Cell-based sensors represent a promising platform for monitoring the metabolic activity and thus, the “welfare” of relevant organisms. In the present study, metabolic responses of the model bacterium Escherichia coli in suspension, layered onto a capacitive field-effect structure, were examined to pulses of glucose in the concentration range between 0.05 and 2 mM. It was found that acidification of the surrounding medium takes place immediately after glucose addition and follows Michaelis–Menten kinetic behavior as a function of the glucose concentration. In future, the presented setup can, therefore, be used to study substrate specificities on the enzymatic level and may as well be used to perform investigations of more complex metabolic responses. Conclusions and perspectives highlighting this system are discussed.