A. Urban - Academia.edu (original) (raw)

Papers by A. Urban

Research paper thumbnail of Track a: biomaterials and biocompatibility

Biomedizinische Technik. Biomedical engineering, 2014

Research paper thumbnail of Biosensor Having Electrode for Determining the Rate of Flow of a Fluid

Research paper thumbnail of New microminiaturized glucose sensors using covalent immobilization techniques

Sensors and Actuators B: Chemical, 1990

Research paper thumbnail of Decorated nanotube buckypaper as electrocatalyst for glucose fuel cells

TRANSDUCERS 2009 - 2009 International Solid-State Sensors, Actuators and Microsystems Conference, 2009

Abstract We present novel metallic/bimetallic (Pt, Au-Pt) nanoparticle-decorated carbon nanotubes... more Abstract We present novel metallic/bimetallic (Pt, Au-Pt) nanoparticle-decorated carbon nanotubes and bilirubin oxidase-decorated carbon nanotubes deposited on nano-tube buckypaper as promising supported electro-catalytic systems and as electrode material ...

Research paper thumbnail of Effect of electrochemical synthesis conditions on deflection of PEDOT bilayers

Sensors and Actuators B: Chemical, 2007

ABSTRACT The deflection of the electrochemically grown poly(3,4-ethylenedioxythiophene) (PEDOT) b... more ABSTRACT The deflection of the electrochemically grown poly(3,4-ethylenedioxythiophene) (PEDOT) bilayers was shown to depend greatly on the polymerisation potential, as established by measurements of bilayer deflection during chronoamperometry experiments. The reproducibility was tested by polymerising PEDOT bilayers at least three times at the same polymerisation potential. Therefore, PEDOT bilayer films obtained at low polymerisation potentials showed high deflection at oxidation, high actuation speed and good durability, while those values decreased for bilayer films obtained at higher polymerisation potentials. Long term cycling characteristics for a PEDOT bilayer polymerised at a low polymerisation potential (1.05V versus Ag/AgAgCl) were tested by actuating the film in 11,000 cycles.

Research paper thumbnail of Nanophase separated amphiphilic polymer co-networks as efficient matrices for optical sensors: Rapid and sensitive detection of NO2

Sensors and Actuators B: Chemical, 2013

A disposable and irreversible sensor for nitrogen dioxide detection, based on the reaction of NO ... more A disposable and irreversible sensor for nitrogen dioxide detection, based on the reaction of NO 2 with N,N-diphenyl-1,4-phenylenediamine (DPPD) is described. This work focuses on the application of silicone-containing amphiphilic co-networks (APCNs) as immobilisation matrices for UV/VIS transmission spectroscopy for gas sensors. The developed flow-through gas sensor is based on a DPPD doped APCN, for real-time spectrophotometric detection of the oxidation product, and is formed in a 34 m thin film. The measurement principle presented here describes the NO 2 concentration as a function of the temporal development of absorption at 450 nm. A linear relationship between the change of absorption and the concentration of NO 2 at different humidity is obtained in the range from 0.1 to 5.0 ppm at ambient temperatures. As a consequence, the sensor response is reproducible with a very low detection threshold (20 ppb) and detection times within seconds.

Research paper thumbnail of A new optochemical chlorine gas sensor based on the application of amphiphilic co-networks as matrices

Sensors and Actuators B: Chemical, 2011

A sensor for chlorine gas detection, consisting of an amphiphilic polymer co-network with an immo... more A sensor for chlorine gas detection, consisting of an amphiphilic polymer co-network with an immobilised oxidation indicator, o-tolidine, is described. Data describing gas sensing properties and long-term stability will be presented. This study focuses on APCN thin films as a matrix for indicator immobilisation. Thin films of poly(2-hydroxyethyl acrylate)-l-polydimethylsiloxane PHEA-l-PDMS were prepared as immobilisation matrices for o-tolidine. We present a simple, non-expensive, but highly sensitive optical sensor for chlorine gas detection. The thin film response is reproducible and irreversible. With our kinetic-optical method rapid response times were achieved. The determination of chlorine is performed on the basis of the oxidation of o-tolidine as the chromogenic reagent to a coloured product which can be monitored at 650 nm. The results reveal a fast response to chlorine gas down to concentrations of 0.01 ppm.

Research paper thumbnail of Silicone Containing Amphiphilic Co-Networks as Immobilisation Matrices for Enzyme based Biosensors: Optochemical Detection of Gaseous Hydrogen Peroxide

Procedia Engineering, 2011

Silicone containing amphiphilic co-networks are used as immobilisation matrix for ABTS (chromopho... more Silicone containing amphiphilic co-networks are used as immobilisation matrix for ABTS (chromophor) and horseradish peroxidase. The good gas diffusion properties as well as the good immobilisation properties of the silicone containing APCNs, reffered to as silicone hydrogels, makes this type of sensors suitable for fast real-time gas detection. Detection of 1 ppm of gaseous peroxide (used as explosive or precursor) is feasible within seconds.

Research paper thumbnail of SECM detection of single boron doped diamond nanodes and nanoelectrode arrays using phase-operated shear force technique

Electrochemistry Communications, 2012

ABSTRACT Boron doped diamond (BDD) is a promising electrode material for electrochemical biosenso... more ABSTRACT Boron doped diamond (BDD) is a promising electrode material for electrochemical biosensor applications due to its low bio-fouling, chemical stability, and large potential window. For the first time, BDD nanoelectrode arrays (NEA) were studied using Scanning Electrochemical Microscopy (SECM) measurements. Using the phase-operated shear force technique and feedback mode, it was possible to scan a platinum (Pt) nanode with an active radius of 167 nm over a diamond array at a constant distance of 45 nm and to detect the electrochemical activity of single BDD nanodes in the 100 nm range.

Research paper thumbnail of Polymer-based, flexible glutamate and lactate microsensors for in vivo applications

Biosensors and Bioelectronics, 2014

We present a flexible microsensor, based on a polymer substrate, for multiparametric, electrochem... more We present a flexible microsensor, based on a polymer substrate, for multiparametric, electrochemical in vivo monitoring. The sensor strip with a microelectrode array at the tip was designed for insertion into tissue, for fast and localized online monitoring of physiological parameters. The microsystem fabrication on a wafer-level is based on a polyimide substrate and includes the patterning of platinum microelectrodes as well as epoxy and dry-film-resist insulation in a cost-effective thin-film and laminate process. A stable, electrodeposited silver/silver chloride reference electrode on-chip and a perm-selective membrane as an efficient interference rejection scheme are integrated on a wafer-level. Amperometric, electrochemical, enzyme-based biosensors for the neurotransmitter L-glutamate and the energy metabolite L-lactate have been developed. Hydrogel membranes or direct cross-linking as stable concepts for the enzyme immobilization are shown. Sensor performance including high selectivity, tailoring of sensitivity and long-term stability is discussed. For glutamate, a high sensitivity of 2.16 nA mm À 2 mM À 1 was found. For lactate, a variation in sensitivity between 2.6 and 32 nA mm À 2 mM À 1 was achieved by different membrane compositions. The in vivo application in an animal model is demonstrated by glutamate measurements in the brain of rats. Local glutamate alterations in the micromolar range and in nanoliterrange volumes can be detected and quantified with high reproducibility and temporal resolution. A novel, versatile platform for the integration of various electrochemical sensors on a small, flexible sensor strip for a variety of in vivo applications is presented.

Research paper thumbnail of Pericellular Oxygen Monitoring during Low-Level Light Therapy in Cell Culture Using a Microsensor System

Proceedings

An electrochemical microsensor system to monitor the pericellular oxygen concentration of fibrobl... more An electrochemical microsensor system to monitor the pericellular oxygen concentration of fibroblasts during low-level light therapy in vitro was developed. The system provides insight into the metabolism of the cells during and in consequence of illumination with visible red light. This approach is a unique method for real-time investigations of cellular respiration during light therapy. The presented sensor system features direct amperometric measurements by using chronoamperometric protocols for long-term stability. The oxygen measurements do not show a disturbance by light.

Research paper thumbnail of Biosensor Having Electrode for Determining the Rate of Flow of a Fluid

Research paper thumbnail of MgO-Doped (Zr,Sr)TiO3 Perovskite Humidity Sensors: Microstructural Effects on Water Permeation

Research paper thumbnail of Polymer-based, flexible glutamate and lactate microsensors for in vivo applications

Biosensors and Bioelectronics, 2014

We present a flexible microsensor, based on a polymer substrate, for multiparametric, electrochem... more We present a flexible microsensor, based on a polymer substrate, for multiparametric, electrochemical in vivo monitoring. The sensor strip with a microelectrode array at the tip was designed for insertion into tissue, for fast and localized online monitoring of physiological parameters. The microsystem fabrication on a wafer-level is based on a polyimide substrate and includes the patterning of platinum microelectrodes as well as epoxy and dry-film-resist insulation in a cost-effective thin-film and laminate process. A stable, electrodeposited silver/silver chloride reference electrode on-chip and a perm-selective membrane as an efficient interference rejection scheme are integrated on a wafer-level. Amperometric, electrochemical, enzyme-based biosensors for the neurotransmitter L-glutamate and the energy metabolite L-lactate have been developed. Hydrogel membranes or direct cross-linking as stable concepts for the enzyme immobilization are shown. Sensor performance including high selectivity, tailoring of sensitivity and long-term stability is discussed. For glutamate, a high sensitivity of 2.16 nAmm(-2) µM(-1) was found. For lactate, a variation in sensitivity between 2.6 and 32 nAmm(-2)mM(-1) was achieved by different membrane compositions. The in vivo application in an animal model is demonstrated by glutamate measurements in the brain of rats. Local glutamate alterations in the micromolar range and in nanoliter-range volumes can be detected and quantified with high reproducibility and temporal resolution. A novel, versatile platform for the integration of various electrochemical sensors on a small, flexible sensor strip for a variety of in vivo applications is presented.

Research paper thumbnail of Decorated nanotube buckypaper as electrocatalyst for glucose fuel cells

International Conference on Solid State Sensors and Actuators, 2009

We present novel metallic/bimetallic (Pt, Au-Pt) nanoparticle-decorated carbon nanotubes and bili... more We present novel metallic/bimetallic (Pt, Au-Pt) nanoparticle-decorated carbon nanotubes and bilirubin oxidase-decorated carbon nanotubes deposited on nano-tube buckypaper as promising supported electro-catalytic systems and as electrode material respectively for mixed-reactant biofuel cell applications at neutral pH. We found that the novel enzyme-decorated carbon nanotubes on nanotube buckypaper material is a promising cathode for glucose biofuel cells. It exhibited a high

Research paper thumbnail of Track a: biomaterials and biocompatibility

Biomedizinische Technik. Biomedical engineering, 2014

Research paper thumbnail of Biosensor Having Electrode for Determining the Rate of Flow of a Fluid

Research paper thumbnail of New microminiaturized glucose sensors using covalent immobilization techniques

Sensors and Actuators B: Chemical, 1990

Research paper thumbnail of Decorated nanotube buckypaper as electrocatalyst for glucose fuel cells

TRANSDUCERS 2009 - 2009 International Solid-State Sensors, Actuators and Microsystems Conference, 2009

Abstract We present novel metallic/bimetallic (Pt, Au-Pt) nanoparticle-decorated carbon nanotubes... more Abstract We present novel metallic/bimetallic (Pt, Au-Pt) nanoparticle-decorated carbon nanotubes and bilirubin oxidase-decorated carbon nanotubes deposited on nano-tube buckypaper as promising supported electro-catalytic systems and as electrode material ...

Research paper thumbnail of Effect of electrochemical synthesis conditions on deflection of PEDOT bilayers

Sensors and Actuators B: Chemical, 2007

ABSTRACT The deflection of the electrochemically grown poly(3,4-ethylenedioxythiophene) (PEDOT) b... more ABSTRACT The deflection of the electrochemically grown poly(3,4-ethylenedioxythiophene) (PEDOT) bilayers was shown to depend greatly on the polymerisation potential, as established by measurements of bilayer deflection during chronoamperometry experiments. The reproducibility was tested by polymerising PEDOT bilayers at least three times at the same polymerisation potential. Therefore, PEDOT bilayer films obtained at low polymerisation potentials showed high deflection at oxidation, high actuation speed and good durability, while those values decreased for bilayer films obtained at higher polymerisation potentials. Long term cycling characteristics for a PEDOT bilayer polymerised at a low polymerisation potential (1.05V versus Ag/AgAgCl) were tested by actuating the film in 11,000 cycles.

Research paper thumbnail of Nanophase separated amphiphilic polymer co-networks as efficient matrices for optical sensors: Rapid and sensitive detection of NO2

Sensors and Actuators B: Chemical, 2013

A disposable and irreversible sensor for nitrogen dioxide detection, based on the reaction of NO ... more A disposable and irreversible sensor for nitrogen dioxide detection, based on the reaction of NO 2 with N,N-diphenyl-1,4-phenylenediamine (DPPD) is described. This work focuses on the application of silicone-containing amphiphilic co-networks (APCNs) as immobilisation matrices for UV/VIS transmission spectroscopy for gas sensors. The developed flow-through gas sensor is based on a DPPD doped APCN, for real-time spectrophotometric detection of the oxidation product, and is formed in a 34 m thin film. The measurement principle presented here describes the NO 2 concentration as a function of the temporal development of absorption at 450 nm. A linear relationship between the change of absorption and the concentration of NO 2 at different humidity is obtained in the range from 0.1 to 5.0 ppm at ambient temperatures. As a consequence, the sensor response is reproducible with a very low detection threshold (20 ppb) and detection times within seconds.

Research paper thumbnail of A new optochemical chlorine gas sensor based on the application of amphiphilic co-networks as matrices

Sensors and Actuators B: Chemical, 2011

A sensor for chlorine gas detection, consisting of an amphiphilic polymer co-network with an immo... more A sensor for chlorine gas detection, consisting of an amphiphilic polymer co-network with an immobilised oxidation indicator, o-tolidine, is described. Data describing gas sensing properties and long-term stability will be presented. This study focuses on APCN thin films as a matrix for indicator immobilisation. Thin films of poly(2-hydroxyethyl acrylate)-l-polydimethylsiloxane PHEA-l-PDMS were prepared as immobilisation matrices for o-tolidine. We present a simple, non-expensive, but highly sensitive optical sensor for chlorine gas detection. The thin film response is reproducible and irreversible. With our kinetic-optical method rapid response times were achieved. The determination of chlorine is performed on the basis of the oxidation of o-tolidine as the chromogenic reagent to a coloured product which can be monitored at 650 nm. The results reveal a fast response to chlorine gas down to concentrations of 0.01 ppm.

Research paper thumbnail of Silicone Containing Amphiphilic Co-Networks as Immobilisation Matrices for Enzyme based Biosensors: Optochemical Detection of Gaseous Hydrogen Peroxide

Procedia Engineering, 2011

Silicone containing amphiphilic co-networks are used as immobilisation matrix for ABTS (chromopho... more Silicone containing amphiphilic co-networks are used as immobilisation matrix for ABTS (chromophor) and horseradish peroxidase. The good gas diffusion properties as well as the good immobilisation properties of the silicone containing APCNs, reffered to as silicone hydrogels, makes this type of sensors suitable for fast real-time gas detection. Detection of 1 ppm of gaseous peroxide (used as explosive or precursor) is feasible within seconds.

Research paper thumbnail of SECM detection of single boron doped diamond nanodes and nanoelectrode arrays using phase-operated shear force technique

Electrochemistry Communications, 2012

ABSTRACT Boron doped diamond (BDD) is a promising electrode material for electrochemical biosenso... more ABSTRACT Boron doped diamond (BDD) is a promising electrode material for electrochemical biosensor applications due to its low bio-fouling, chemical stability, and large potential window. For the first time, BDD nanoelectrode arrays (NEA) were studied using Scanning Electrochemical Microscopy (SECM) measurements. Using the phase-operated shear force technique and feedback mode, it was possible to scan a platinum (Pt) nanode with an active radius of 167 nm over a diamond array at a constant distance of 45 nm and to detect the electrochemical activity of single BDD nanodes in the 100 nm range.

Research paper thumbnail of Polymer-based, flexible glutamate and lactate microsensors for in vivo applications

Biosensors and Bioelectronics, 2014

We present a flexible microsensor, based on a polymer substrate, for multiparametric, electrochem... more We present a flexible microsensor, based on a polymer substrate, for multiparametric, electrochemical in vivo monitoring. The sensor strip with a microelectrode array at the tip was designed for insertion into tissue, for fast and localized online monitoring of physiological parameters. The microsystem fabrication on a wafer-level is based on a polyimide substrate and includes the patterning of platinum microelectrodes as well as epoxy and dry-film-resist insulation in a cost-effective thin-film and laminate process. A stable, electrodeposited silver/silver chloride reference electrode on-chip and a perm-selective membrane as an efficient interference rejection scheme are integrated on a wafer-level. Amperometric, electrochemical, enzyme-based biosensors for the neurotransmitter L-glutamate and the energy metabolite L-lactate have been developed. Hydrogel membranes or direct cross-linking as stable concepts for the enzyme immobilization are shown. Sensor performance including high selectivity, tailoring of sensitivity and long-term stability is discussed. For glutamate, a high sensitivity of 2.16 nA mm À 2 mM À 1 was found. For lactate, a variation in sensitivity between 2.6 and 32 nA mm À 2 mM À 1 was achieved by different membrane compositions. The in vivo application in an animal model is demonstrated by glutamate measurements in the brain of rats. Local glutamate alterations in the micromolar range and in nanoliterrange volumes can be detected and quantified with high reproducibility and temporal resolution. A novel, versatile platform for the integration of various electrochemical sensors on a small, flexible sensor strip for a variety of in vivo applications is presented.

Research paper thumbnail of Pericellular Oxygen Monitoring during Low-Level Light Therapy in Cell Culture Using a Microsensor System

Proceedings

An electrochemical microsensor system to monitor the pericellular oxygen concentration of fibrobl... more An electrochemical microsensor system to monitor the pericellular oxygen concentration of fibroblasts during low-level light therapy in vitro was developed. The system provides insight into the metabolism of the cells during and in consequence of illumination with visible red light. This approach is a unique method for real-time investigations of cellular respiration during light therapy. The presented sensor system features direct amperometric measurements by using chronoamperometric protocols for long-term stability. The oxygen measurements do not show a disturbance by light.

Research paper thumbnail of Biosensor Having Electrode for Determining the Rate of Flow of a Fluid

Research paper thumbnail of MgO-Doped (Zr,Sr)TiO3 Perovskite Humidity Sensors: Microstructural Effects on Water Permeation

Research paper thumbnail of Polymer-based, flexible glutamate and lactate microsensors for in vivo applications

Biosensors and Bioelectronics, 2014

We present a flexible microsensor, based on a polymer substrate, for multiparametric, electrochem... more We present a flexible microsensor, based on a polymer substrate, for multiparametric, electrochemical in vivo monitoring. The sensor strip with a microelectrode array at the tip was designed for insertion into tissue, for fast and localized online monitoring of physiological parameters. The microsystem fabrication on a wafer-level is based on a polyimide substrate and includes the patterning of platinum microelectrodes as well as epoxy and dry-film-resist insulation in a cost-effective thin-film and laminate process. A stable, electrodeposited silver/silver chloride reference electrode on-chip and a perm-selective membrane as an efficient interference rejection scheme are integrated on a wafer-level. Amperometric, electrochemical, enzyme-based biosensors for the neurotransmitter L-glutamate and the energy metabolite L-lactate have been developed. Hydrogel membranes or direct cross-linking as stable concepts for the enzyme immobilization are shown. Sensor performance including high selectivity, tailoring of sensitivity and long-term stability is discussed. For glutamate, a high sensitivity of 2.16 nAmm(-2) µM(-1) was found. For lactate, a variation in sensitivity between 2.6 and 32 nAmm(-2)mM(-1) was achieved by different membrane compositions. The in vivo application in an animal model is demonstrated by glutamate measurements in the brain of rats. Local glutamate alterations in the micromolar range and in nanoliter-range volumes can be detected and quantified with high reproducibility and temporal resolution. A novel, versatile platform for the integration of various electrochemical sensors on a small, flexible sensor strip for a variety of in vivo applications is presented.

Research paper thumbnail of Decorated nanotube buckypaper as electrocatalyst for glucose fuel cells

International Conference on Solid State Sensors and Actuators, 2009

We present novel metallic/bimetallic (Pt, Au-Pt) nanoparticle-decorated carbon nanotubes and bili... more We present novel metallic/bimetallic (Pt, Au-Pt) nanoparticle-decorated carbon nanotubes and bilirubin oxidase-decorated carbon nanotubes deposited on nano-tube buckypaper as promising supported electro-catalytic systems and as electrode material respectively for mixed-reactant biofuel cell applications at neutral pH. We found that the novel enzyme-decorated carbon nanotubes on nanotube buckypaper material is a promising cathode for glucose biofuel cells. It exhibited a high