B. Lübbers

Technische Universität Ilmenau

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Trends

Author Order

Document Type

Co-Authors

Andreas Schober

Technische Universität Ilmenau

Michael Gebinoga

Technische Universität Ilmenau

M. Kittler

Walter de Gruyter (Germany)

Frank Weise

Natural and Medical Sciences Institute

I. Cimalla

Technische Universität Ilmenau

Dennis Wegener

Pediatric Oncology Group

V. Lebedev

Fraunhofer Institute for Applied Solid State Physics

Mary J. Donahue

Linköping University

G. Kittler

X-Fab (Germany)

Liele Silveira

Technische Universität Ilmenau

Cooperative Institutions

Technische Universität Ilmenau

Kirchhoff (Germany)

Karlsruhe Institute of Technology

Fraunhofer Institute for Applied Solid State Physics

FZI Research Center for Information Technology

Fraunhofer Society

FIZ Karlsruhe – Leibniz Institute for Information Infrastructure

Leibniz Institute of Photonic Technology

Heidelberg University

Foundation for Research and Technology Hellas

Author Statistics

Papers

Citation

H-Index

i-10 index

Research Field

A novel GaN‐based multiparameter sensor system for biochemical analysis

Physica status solidi. C, Conferences and critical reviews/Physica status solidi. C, Current topics in solid state physics (2008)

B. Lübbers G. Kittler P. Ort St. Linkohr Dennis Wegener

Abstract GaN and its ternary alloys offer several advantages for the fabrication of biochemical sensors systems due to their chemical stability and optical transparency. We employ ion‐sensitive field effect transistors (ISFET) based on a surface sensitive AlGaN/GaN heterostructure. Combined with a picoliter dosing system, an integrated micro reference electrode and an optical spectroscopy system a novel multi‐parameter analysis system for aqueous solutions in the micro‐ to nanoliter range was constructed. Application examples are presented to illustrate the application potential of the sensor system e.g. in the high‐throughput screening of cancer drugs. Simultaneous opto‐electrochemical monitoring of enzyme reaction kinetics by pH and absorption measurements in 700 nl and parallel automated measurements with functionalized enzyme‐modified FETs (EnFET) and a reference ISFET in 3 µl are demonstrated. The experimental data obtained agree well with published values for the reaction kinetic and with reference measurements performed with a state‐of‐the‐art pH‐meter and spectrophotometer which require 1000‐fold larger volumes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

ISFET

10.1002/pssc.200778726

Cite

Citations (13)

Nerve cell response to inhibitors recorded with an aluminum–galliumnitride/galliumnitride field-effect transistor

Journal of Neuroscience Methods (2012)

Michael Gebinoga Patrick Mai Mary J. Donahue M. Kittler I. Cimalla

ISFET

10.1016/j.jneumeth.2012.02.018

Cite

Citations (9)

AlGaN/GaN-sensors for monitoring of enzyme activity by pH-measurements

CD-ROM-Ausg.:#R#<br/>Information technology and electrical engineering - devices and systems, materials and technologies for the future : 51. IWK, Internationales Wissenschaftliches Kolloquium ; proceedings ; 11 - 15 September 2006 / Faculty of Electrical and Information Technology, Technische Universität Ilmenau. - Ilmenau : Verl. ISLE, 2006. - ISBN 3-938843-16-0 (2009)

G. Kittler Armin Spitznas B. Lübbers V. Lebedev Dennis Wegener

Source

Cite

Citations (1)

Comparing the ISFET to the glass electrode: advantages, challenges and similarities

Chemia Analityczna (2009)

B. Lübbers Andreas Schober

In this review we compare the glass electrode to the ion-sensitive field-effect transistor (ISFET) with regard to the determination of pH. A brief overview of electrochemical methods to determine pH is given to put both devices in historical context. The dissociation is discussed as the most appropriate theoretical description of the phase boundary potential generation at the glass electrode. This bears remarkable similarities to the site-dissociation model which is presented for the charging mechanism at the ISFET/solution interface. It is concluded that the theories behind both devices primarily differ from each other by the charge balancing mechanism. From the discussion of the device properties it is inferred that the ISFET exhibits some advantages (e.g. size, robustness, response time) over the glass electrode, but also suffers from packaging challenges and a more complex temperature dependence. Nevertheless, with regard to application fields the glass electrode remains the undisputed gold standard. The ISFET is only slowly gaining ground in the market with special robust devices, e.g. for the food industry, as well as miniaturized systems in biomedical applications.

ISFET

Glass electrode

Source

Cite

Citations (4)

AlGaN-based pH-sensors: impedance characterisation, optimisation and application for foetal blood sampling

B. Lübbers

Die fotale Mikroblutuntersuchung wird zur Uberwachung der Sauerstoffversorgung von Foten wahrend der Geburt eingesetzt. Mit herkommlichen Blutgasanalysatoren kommt es allerdings immer wieder zu Schwierigkeiten da nur sehr geringe Mengen fotalen Blutes (wenige 10 μl) fur die Untersuchung zur Verfugung stehen. Ionensensitiven Feldeffekttransistoren (ISFET) bieten durch ihre Miniaturisierbarkeit das Potential das benotigte Volumen wesentlich zu reduzieren. In der vorliegenden Arbeit wird die Grundlage fur die Anwendung von Aluminium-Gallium-Nitrid(AlGaN)-basierten ISFETs fur die fotale Mikroblutuntersuchung geschaffen. Dazu werden AlGaN/GaN-Heterostrukturen mit Metall- und Elektrolytkontakt impedanzspektroskopisch charakterisiert. Es wird gezeigt, dass das standardmasig verwendete eindimensionale Ersatzschaltbild die zweidimensionale Verarmungscharakteristik des zweidimensionalen Elektronengases nicht ausreichend genau beschreibt. Daher wird ein erweitertes Ersatzschaltbild unter Verwendung von sogenannten constant phase elements hergeleitet und verifiziert. Auf Basis des neuen Ersatzschaltbildes werden Drifteinflusse charakterisiert sowie die pH-Sensitivitat der AlGaN-pH-Sensoren bestimmt. Neben der lichtinduzierten Drift durch persistente Photoleitung, kann auch eine langsame elektrochemische Korrosion des Sensors nachgewiesen werden. Fur die Reduzierung der lichtinduzierten Drift wird die kontinuierliche Beleuchtung der Sensoren untersucht und eine deutliche Verkurzung der Driftdauer fur rotes Licht festgestellt. Die Vergroserung der Dicke der GaN-Deckschicht und die Reduzierung des Aluminiumgehalts in der AlGaN Barriereschicht erhoht nachweislich die Korrosionbestandigkeit der Sensoren. Unter Verwendung dieser Optimierungsschritte wird gezeigt, dass eine Genauigkeit von ±0.03pH fur die pH-Wert-Bestimmung in verschiedenste wassrige Losungen sowie fur Nabelschnurblut erreicht werden kann. Die erzielten Ergebnisse werden fur die Entwicklung eines Mikro-Blut-pH Analysators mit einem Minimal-Probenvolumen von nur 10μl verwendet, der die Genauigkeits- und Prazisionsanforderungen der Richtlinie der Bundesartzekammer erfullt. Im Rahmen dieser Arbeit wird damit erstmalig gezeigt, dass AlGaN-basierte pH-Sensoren fur die genaue und prazise Bestimmung des pH-Wertes in komplexen biochemischen Flussigkeiten wie z.B. Nabelschnurblut geeignet sind.

Source

Cite

Citations (0)

A novel class of sensors for micro- and nanofluidic systems in biotechnological applications.

Andreas Schober G. Kittler B. Lübbers C. Buchheim A. Majdeddin

Nanofluidics

Source

Cite

Citations (0)

Intrinsically limited mobility of the two-dimensional electron gas in gated AlGaN/GaN and AlGaN/AlN/GaN heterostructures

Journal of Applied Physics (2009)

V. M. Polyakov Frank Schwierz I. Cimalla M. Kittler B. Lübbers

We report on the intrinsically limited low-field mobility of the two-dimensional electron gas (2DEG) in gated AlGaN/GaN and AlGaN/AlN/GaN heterostructures. Monte Carlo transport simulations are carried out to calculate the room-temperature 2DEG mobilities in dependence on the electron sheet density. The simulated 2DEG mobilities are compared to the phonon-limited mobility of bulk GaN. We estimate a maximum 2DEG mobility of about 2700 cm2 V−1 s−1 for an electron sheet density of ∼5×1012 cm−2, which remarkably exceeds the phonon-limited bulk mobility of 1520 cm2 V−1 s−1. By reducing the electron sheet density below 5×1012 cm−2, i.e., in a weak electron quantum confinement regime, the room-temperature 2DEG mobility gradually decreases and approaches the phonon-limited bulk value for vanishing quantum confinement. The insertion of a thin AlN barrier interlayer improves transport properties of the 2DEG and the mobility substantially increases due to a suppression of the alloy scattering.

Electron Mobility

10.1063/1.3174441

Cite

Citations (39)

Nanosensors for label-free measurement of sodium ion fluxes of neuronal cells

Materials Science and Engineering B (2010)

Michael Gebinoga Liele Silveira I. Cimalla Andreea Dumitrescu M. Kittler

Nanosensor

10.1016/j.mseb.2009.12.053

Cite

Citations (8)

Microfluidics and biosensors as tools for NanoBioSystems research with applications in the “Life Science”

Materials Science and Engineering B (2009)

Andreas Schober Caroline Augspurger Uta Fernekorn Karl‐Friedrich Weibezahn Gregor Schlingloff

Nanosensor

Microtechnology

Fluidics

Biocompatible material

10.1016/j.mseb.2009.12.042

Cite

Citations (13)

Applied nano bio systems with microfluidics and biosensors for three‐dimensional cell culture

Materialwissenschaft und Werkstofftechnik (2011)

Andreas Schober Uta Fernekorn B. Lübbers Jörg Hampl Frank Weise

Abstract Applications of nanotechnology and microtechnology lead to a field which could be called nanosystems integration. The next step is the development of nanobiotechnological systems, which could reflect the hierarchical organization of biological systems that utilise scales and laws of nature on all metric scales. As one example of such systems we present the design and construction of a new class of micro bioreactors. It has been shown that 3D culture systems reveal the in vivo situation much better than the cultivation of 2D one cell type alone. For this purpose we have to construct and arrange fluidic devices and a cell‐biological environment in such a way, that living cells can survive in a three‐dimensional, organ‐like structure, enabled by technical devices. Such organ‐like cell structures may lead to new ways in medicinal chemistry for the determination of ADME/Tox (absorption‐distribution‐metabolism‐excretion and toxicity) properties of potential drugs. One part of the construction principle is the integration of sensors, preferable novel AlGaN/GaN nanosensors. The latter nanosensors offer the possibility to estimate reactions of cells attached to the sensor surface non‐destructively and label‐free. These sensors are highly sensitive and biocompatible to cells. Furthermore, they are transparent to enable microscopic and other optical observations of the cells. In an advanced version the sensor is to be integrated to give a better insight into cellular processes of the cells that are cultivated in such micro bioreactors.

Microtechnology

Nanosensor

Fluidics

Biocompatible material

10.1002/mawe.201100746

Cite

Citations (6)