TY - JOUR A1 - Özsoylu, Dua A1 - Kizildag, Sefa A1 - Schöning, Michael Josef A1 - Wagner, Torsten T1 - Differential chemical imaging of extracellular acidification within microfluidic channels using a plasma-functionalized light-addressable potentiometric sensor (LAPS) JF - Physics in Medicine N2 - Extracellular acidification is a basic indicator for alterations in two vital metabolic pathways: glycolysis and cellular respiration. Measuring these alterations by monitoring extracellular acidification using cell-based biosensors such as LAPS plays an important role in studying these pathways whose disorders are associated with numerous diseases including cancer. However, the surface of the biosensors must be specially tailored to ensure high cell compatibility so that cells can represent more in vivo-like behavior, which is critical to gain more realistic in vitro results from the analyses, e.g., drug discovery experiments. In this work, O2 plasma patterning on the LAPS surface is studied to enhance surface features of the sensor chip, e.g., wettability and biofunctionality. The surface treated with O2 plasma for 30 s exhibits enhanced cytocompatibility for adherent CHO–K1 cells, which promotes cell spreading and proliferation. The plasma-modified LAPS chip is then integrated into a microfluidic system, which provides two identical channels to facilitate differential measurements of the extracellular acidification of CHO–K1 cells. To the best of our knowledge, it is the first time that extracellular acidification within microfluidic channels is quantitatively visualized as differential (bio-)chemical images. Y1 - 2020 U6 - http://dx.doi.org/10.1016/j.phmed.2020.100030 SN - 2352-4510 VL - 10 IS - 100030 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Özsoylu, Dua A1 - Kizildag, Sefa A1 - Schöning, Michael Josef A1 - Wagner, Torsten T1 - Effect of plasma treatment on the sensor properties of a light‐addressable potentiometric sensor (LAPS) JF - physica status solidi a : applications and materials sciences N2 - A light-addressable potentiometric sensor (LAPS) is a field-effect-based (bio-) chemical sensor, in which a desired sensing area on the sensor surface can be defined by illumination. Light addressability can be used to visualize the concentration and spatial distribution of the target molecules, e.g., H+ ions. This unique feature has great potential for the label-free imaging of the metabolic activity of living organisms. The cultivation of those organisms needs specially tailored surface properties of the sensor. O2 plasma treatment is an attractive and promising tool for rapid surface engineering. However, the potential impacts of the technique are carefully investigated for the sensors that suffer from plasma-induced damage. Herein, a LAPS with a Ta2O5 pH-sensitive surface is successfully patterned by plasma treatment, and its effects are investigated by contact angle and scanning LAPS measurements. The plasma duration of 30 s (30 W) is found to be the threshold value, where excessive wettability begins. Furthermore, this treatment approach causes moderate plasma-induced damage, which can be reduced by thermal annealing (10 min at 300 °C). These findings provide a useful guideline to support future studies, where the LAPS surface is desired to be more hydrophilic by O2 plasma treatment. Y1 - 2019 U6 - http://dx.doi.org/10.1002/pssa.201900259 SN - 1862-6319 N1 - Corresponding author: Torsten Wagner VL - 216 IS - 20 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Yoshinobu, Tatsuo A1 - Miyamoto, Ko-ichiro A1 - Werner, Frederik A1 - Poghossian, Arshak A1 - Wagner, Torsten A1 - Schöning, Michael Josef T1 - Light-addressable potentiometric sensors for quantitative spatial imaging of chemical species JF - Annual Review of Analytical Chemistry N2 - A light-addressable potentiometric sensor (LAPS) is a semiconductor-based chemical sensor, in which a measurement site on the sensing surface is defined by illumination. This light addressability can be applied to visualize the spatial distribution of pH or the concentration of a specific chemical species, with potential applications in the fields of chemistry, materials science, biology, and medicine. In this review, the features of this chemical imaging sensor technology are compared with those of other technologies. Instrumentation, principles of operation, and various measurement modes of chemical imaging sensor systems are described. The review discusses and summarizes state-of-the-art technologies, especially with regard to the spatial resolution and measurement speed; for example, a high spatial resolution in a submicron range and a readout speed in the range of several tens of thousands of pixels per second have been achieved with the LAPS. The possibility of combining this technology with microfluidic devices and other potential future developments are discussed. Y1 - 2017 U6 - http://dx.doi.org/10.1146/annurev-anchem-061516-045158 SN - 1936-1327 VL - 10 SP - 225 EP - 246 PB - Annual Reviews CY - Palo Alto, Calif. ER - TY - CHAP A1 - Yoshinobu, Tatsuo A1 - Miyamoto, Ko-Ichiro A1 - Wagner, Torsten A1 - Schöning, Michael Josef ED - Yamaguchi, Takami T1 - Miniaturized and high-speed chemical imaging systems T2 - Nano-Biomedical Engineering 2012. Proceedings of the Tohoku University Global Centre of Excellence Programme, Sakura Hall, Tohoku University, Sendai Japan, 5 – 6 March 2012 Y1 - 2012 U6 - http://dx.doi.org/10.1142/9781848169067_0045 SP - 386 EP - 395 PB - World Scientific CY - Singapur ER - TY - JOUR A1 - Yoshinobu, Tatsuo A1 - Miyamoto, Ko-ichiro A1 - Wagner, Torsten A1 - Schöning, Michael Josef T1 - Recent developments of chemical imaging sensor systems based on the principle of the light-addressable potentiometric sensor JF - Sensors and actuators B: Chemical N2 - The light-addressable potentiometric sensor (LAPS) is an electrochemical sensor with a field-effect structure to detect the variation of the Nernst potential at its sensor surface, the measured area on which is defined by illumination. Thanks to this light-addressability, the LAPS can be applied to chemical imaging sensor systems, which can visualize the two-dimensional distribution of a particular target ion on the sensor surface. Chemical imaging sensor systems are expected to be useful for analysis of reaction and diffusion in various electrochemical and biological samples. Recent developments of LAPS-based chemical imaging sensor systems, in terms of the spatial resolution, measurement speed, image quality, miniaturization and integration with microfluidic devices, are summarized and discussed. Y1 - 2015 U6 - http://dx.doi.org/10.1016/j.snb.2014.09.002 SN - 1873-3077 (E-Journal); 0925-4005 (Print) VL - 207, Part B SP - 926 EP - 932 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Yoshinobu, Tatsuo A1 - Miyamoto, Ko-ichiro A1 - Wagner, Torsten A1 - Schöning, Michael Josef T1 - Field-effect sensors combined with the scanned light pulse technique: from artificial olfactory images to chemical imaging technologies JF - Chemosensors N2 - The artificial olfactory image was proposed by Lundström et al. in 1991 as a new strategy for an electronic nose system which generated a two-dimensional mapping to be interpreted as a fingerprint of the detected gas species. The potential distribution generated by the catalytic metals integrated into a semiconductor field-effect structure was read as a photocurrent signal generated by scanning light pulses. The impact of the proposed technology spread beyond gas sensing, inspiring the development of various imaging modalities based on the light addressing of field-effect structures to obtain spatial maps of pH distribution, ions, molecules, and impedance, and these modalities have been applied in both biological and non-biological systems. These light-addressing technologies have been further developed to realize the position control of a faradaic current on the electrode surface for localized electrochemical reactions and amperometric measurements, as well as the actuation of liquids in microfluidic devices. KW - visualization KW - light-addressing technologies KW - scanned light pulse technique KW - field-effect structure KW - MOS KW - metal-oxide-semiconductor structure KW - catalytic metal KW - electronic nose KW - gas sensor KW - artificial olfactory image Y1 - 2024 U6 - http://dx.doi.org/10.3390/chemosensors12020020 SN - 2227-9040 N1 - This article belongs to the Special Issue "An Exciting Journey of Chemical Sensors and Biosensors: A Theme Issue in Honor of Professor Ingemar Lundström" Corresponding author: Tatsuo Yoshinobu, Michael J. Schöning VL - 12 IS - 2 PB - MDPI CY - Basel ER - TY - CHAP A1 - Yoshinobu, Tatsuo A1 - Krause, Steffi A1 - Miyamoto, Ko-ichiro A1 - Werner, Frederik A1 - Poghossian, Arshak A1 - Wagner, Torsten A1 - Schöning, Michael Josef T1 - (Bio-)chemical Sensing and Imaging by LAPS and SPIM T2 - Label-free biosensing: advanced materials, devices and applications N2 - 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. KW - Chemical imaging KW - Field-effect device KW - Light-addressable potentiometric sensor KW - Potentiometry Y1 - 2018 SN - 978-3-319-75219-8 SP - 103 EP - 132 PB - Springer CY - Cham ER - TY - JOUR A1 - Yoshinobu, T. A1 - Iwasaki, H. A1 - Ui, Y. A1 - Furuichi, K. A1 - Ermelenko, Y. A1 - Mourzina, Y. A1 - Wagner, Torsten A1 - Näther, Niko A1 - Schöning, Michael Josef T1 - The light-addressable potentiometric sensor for multi-ion sensing and imaging JF - Methods. 37 (2005), H. 1 Y1 - 2005 SN - 1046-2023 SP - 99 EP - 102 ER - TY - CHAP A1 - Werner, Frederik A1 - Yoshinobu, T. A1 - Miyamoto, K. A1 - Schöning, Michael Josef A1 - Wagner, Torsten T1 - Semiconductor-based sensors for imaging of chemical processes T2 - Sensoren und Messsysteme 2014 ; Beiträge der 17. GMA/ITG-Fachtagung vom 3. bis 4. Juni 2014 in Nürnberg. (ITG-Fachbericht ; 250) Y1 - 2014 SN - 978-3-8007-3622-5 SP - 1 EP - 5 PB - VDE-Verl. CY - Düsseldorf ER - TY - JOUR A1 - Werner, Frederik A1 - Wagner, Torsten A1 - Yoshinobu, Tatsuo A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Frequency behaviour of light-addressable potentiometric sensors JF - Physica Status Solidi (A) N2 - Light-addressable potentiometric sensors (LAPS) are semiconductor-based potentiometric sensors, with the advantage to detect the concentration of a chemical species in a liquid solution above the sensor surface in a spatially resolved manner. The addressing is achieved by a modulated and focused light source illuminating the semiconductor and generating a concentration-depending photocurrent. This work introduces a LAPS set-up that is able to monitor the electrical impedance in addition to the photocurrent. The impedance spectra of a LAPS structure, with and without illumination, as well as the frequency behaviour of the LAPS measurement are investigated. The measurements are supported by electrical equivalent circuits to explain the impedance and the LAPS-frequency behaviour. The work investigates the influence of different parameters on the frequency behaviour of the LAPS. Furthermore, the phase shift of the photocurrent, the influence of the surface potential as well as the changes of the sensor impedance will be discussed. Y1 - 2013 U6 - http://dx.doi.org/10.1002/pssa.201200929 SN - 1521-396X ; 0031-8965 VL - 210 IS - 5 SP - 884 EP - 891 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Werner, Frederik A1 - Wagner, Torsten A1 - Miyamoto, Ko-ichiro A1 - Yoshinobu, Tatsuo A1 - Schöning, Michael Josef T1 - High speed and high resolution chemical imaging based on a new type of OLED-LAPS set-up JF - Sensors and Actuators B: Chemical N2 - Light-addressable potentiometric sensors (LAPS) are field-effect-based sensors. A modulated light source is used to define the particular measurement spot to perform spatially resolved measurements of chemical species and to generate chemical images. In this work, an organic-LED (OLED) display has been chosen as a light source. This allows high measurement resolution and miniaturisation of the system. A new developed driving method for the OLED display optimised for LAPS-based measurements is demonstrated. The new method enables to define modulation frequencies between 1 kHz and 16 kHz and hence, reduces the measurement time of a chemical image by a factor of 40 compared to the traditional addressing of an OLED display. Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.snb.2011.12.102 SN - 0925-4005 N1 - Part of special issue "Selected Papers presented at Eurosensors XXV" VL - 175 SP - 118 EP - 122 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Werner, Frederik A1 - Wagner, Torsten A1 - Miyamoto, Ko-ichiro A1 - Yoshinobu, Tatsuo A1 - Schöning, Michael Josef T1 - High speed and high resolution chemical imaging based on a new type of OLED-LAPS set-up JF - Procedia Engineering. 25 (2011) Y1 - 2011 SN - 1877-7058 N1 - EurosensorsXXV ; Proc. Eurosensors XXV, September 4-7, 2011, Athens, Greece SP - 346 EP - 349 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Werner, Frederik A1 - Spelthahn, H. A1 - Schöning, Michael Josef A1 - Krumbe, C. A1 - Wagner, Torsten A1 - Yoshinobu, T. A1 - Keusgen, M. T1 - Neue Ansteuerungselektronik für LAPS-basierte Biosensoren zur gleichzeitig ortsaufgelösten Messung der pH-Konzentration JF - Sensoren und Messsysteme 2010 [Elektronische Ressource] : Vorträge der 15. ITG/GMA-Fachtagung vom 18. bis 19. Mai 2010 in Nürnberg / Informationstechnische Gesellschaft im VDE (ITG); VDI/VDE-Gesellschaft Mess- und Automatisierungstechnik (GMA) Y1 - 2010 SN - 978-3-8007-3260-9 N1 - Fachtagung Sensoren und Messsysteme 15, 2010, Nürnberg ; Gesellschaft Mess- und Automatisierungstechnik SP - 109 EP - 114 PB - VDE Verlag CY - Berlin ER - TY - JOUR A1 - Werner, Frederik A1 - Schusser, Sebastian A1 - Spalthahn, Heiko A1 - Wagner, Torsten A1 - Yoshinobu, Tatsuo A1 - Schöning, Michael Josef T1 - Field-programmable gate array based controller for multi spot light-addressable potentiometric sensors with integrated signal correction mode JF - Electrochimica Acta N2 - A light-addressable potentiometric sensor (LAPS) can measure the concentration of one or several analytes at the sensor surface simultaneously in a spatially resolved manner. A modulated light pointer stimulates the semiconductor structure at the area of interest and a responding photocurrent can be read out. By simultaneous stimulation of several areas with light pointers of different modulation frequencies, the read out can be performed at the same time. With the new proposed controller electronic based on a field-programmable gate array (FPGA), it is possible to control the modulation frequencies, phase shifts, and light brightness of multiple light pointers independently and simultaneously. Thus, it is possible to investigate the frequency response of the sensor, and to examine the analyte concentration by the determination of the surface potential with the help of current/voltage curves and phase/voltage curves. Additionally, the ability to individually change the light intensities of each light pointer is used to perform signal correction. Y1 - 2011 U6 - http://dx.doi.org/10.1016/j.electacta.2011.03.012 SN - 0013-4686 VL - 56 IS - 26 SP - 9656 EP - 9660 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Werner, Frederik A1 - Miyamoto, Ko-ichiro A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Lateral resolution enhancement of pulse-driven light-addressable potentiometric sensor JF - Sensor and Actuators B: Chemical N2 - 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. KW - Chemical images KW - LAPS KW - Light-addressable potentiometric sensor Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.snb.2017.02.057 SN - 0925-4005 VL - 248 SP - 961 EP - 965 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Werner, Frederik A1 - Mansour, Ahmed A1 - Rateike, Franz-Matthias A1 - Schusser, Sebastian A1 - Wagner, Torsten A1 - Yoshinobu, Tatsuo A1 - Keusgen, Michael A1 - Schöning, Michael Josef ED - Gerlach, Gerald T1 - Kompakter Aufbau eines lichtadressierbaren potentiometrischen Sensors mit verfahrbarem Diodenlaser T2 - 10. Dresdner Sensor-Symposium : Dresden, 5. - 7. Dezember 2011 ; miniaturisierte analytische Verfahren, Hochtemperatur-Sensoren, Sensoren für Bioprozess- und Verfahrenstechnik, Sensoren für die Medizin, Chemische Verfahrenstechnik, Lebensmittelanalytik, innovative Sensorlösungen, Sensoren für die Wasserqualität, Selbstüberwachung / Gerald Gerlach ... (Hg.) Dresdner Beiträge zur Sensorik. 43 Y1 - 2011 SN - 978-3-942710-53-4 SP - 277 EP - 280 PB - TUDpress CY - Dresden ER - TY - JOUR A1 - Werner, Frederik A1 - Krumbe, Christoph A1 - Schumacher, Katharina A1 - Groebel, Simone A1 - Spelthahn, Heiko A1 - Stellberg, Michael A1 - Wagner, Torsten A1 - Yoshinobu, Tatsuo A1 - Selmer, Thorsten A1 - Keusgen, Michael A1 - Baumann, Marcus A1 - Schöning, Michael Josef T1 - Determination of the extracellular acidification of Escherichia coli by a light-addressable potentiometric sensor JF - Physica status solidi (a) : applications and material science. 208 (2011), H. 6 Y1 - 2011 SN - 1862-6319 SP - 1340 EP - 1344 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Werner, Frederik A1 - Groebel, Simone A1 - Wagner, Torsten A1 - Yoshinobu, Tatsuo A1 - Selmer, Thorsten A1 - Baumann, Marcus A1 - Schöning, Michael Josef T1 - Überwachung der metabolischen Aktivität von Mikroorganismen zur Kontrolle des biologischen Prozesses im Biogasfermenter JF - Biogas 2011 : Energieträger der Zukunft ; 6. Fachtagung, Fachtagung Braunschweig, 08. und 09. Juni 2011 / VDI Energie und Umwelt Y1 - 2011 SN - 978-3-18-092121-1 N1 - Gesellschaft Energie und Umwelt ; Fachtagung Biogas ; (6 : ; 2011.06.08-09 : ; Braunschweig) ; VDI-Berichte ; 2121 SP - 285 EP - 286 PB - VDI-Verl. CY - Düsseldorf ER - TY - JOUR A1 - Werner, Frederik A1 - Groebel, Simone A1 - Schuhmacher, K. A1 - Spelthahn, Heiko A1 - Wagner, Torsten A1 - Selmer, Thorsten A1 - Baumann, Marcus A1 - Schöning, Michael Josef T1 - Bestimmung der metabolischen Aktivität von Mikroorganismen während des Biogasbildungsprozesses JF - 9. Dresdner Sensor-Symposium : Dresden, 07.-09. Dezember 2009 / Gerlach, Gerald ; Hauptmann, Peter [Hrsg.] Y1 - 2009 SN - 978-3-941298-44-6 N1 - Dresdner Sensor-Symposium ; (9, 2009, Dresden) SP - 201 EP - 204 PB - TUDpress CY - Dresden ER - TY - JOUR A1 - Werner, Frederik A1 - Groebel, Simone A1 - Krumbe, Christoph A1 - Wagner, Torsten A1 - Selmer, Thorsten A1 - Yoshinobu, Tatsuo A1 - Baumann, Marcus A1 - Schöning, Michael Josef T1 - Nutrient concentration-sensitive microorganism-based biosensor JF - Physica Status Solidi (a) Y1 - 2012 U6 - http://dx.doi.org/10.1002/pssa.201100801 SN - 1862-6319 VL - 209 IS - 5 SP - 900 EP - 904 PB - Wiley-VCH CY - Weinheim ER -