@article{WernerWagnerMiyamotoetal.2012,
  author    = {Werner, Frederik and Wagner, Torsten and Miyamoto, Ko-ichiro and Yoshinobu, Tatsuo and Sch{\"o}ning, Michael Josef},
  title     = {High speed and high resolution chemical imaging based on a new type of OLED-LAPS set-up},
  series = {Sensors and Actuators B: Chemical},
  volume    = {175},
  journal   = {Sensors and Actuators B: Chemical},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0925-4005},
  doi       = {10.1016/j.snb.2011.12.102},
  pages     = {118 -- 122},
  year      = {2012},
  abstract  = {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.},
  language  = {en}
}
@article{MiyamotoSugawaraKanohetal.2010,
  author    = {Miyamoto, Ko-ichiro and Sugawara, Yuri and Kanoh, Shin´ichiro and Yoshinobu, Tatsuo and Wagner, Torsten and Sch{\"o}ning, Michael Josef},
  title     = {Image correction method for the chemical imaging sensor},
  series = {Sensors and Actuators B: Chemical. 144 (2010), H. 2},
  journal   = {Sensors and Actuators B: Chemical. 144 (2010), H. 2},
  pages     = {344 -- 348},
  year      = {2010},
  language  = {en}
}
@article{MiyamotoWagnerMimuraetal.2009,
  author    = {Miyamoto, Ko-ichiro and Wagner, Torsten and Mimura, Shuhei and Kanoh, Shin`ichiro and Yoshinobu, Tatsuo and Sch{\"o}ning, Michael Josef},
  title     = {Constant-phase-mode operation of the light-addressable potentiometric sensor},
  series = {Procedia Chemistry. 1 (2009), H. 1},
  journal   = {Procedia Chemistry. 1 (2009), H. 1},
  publisher = {Elsevier},
  address   = {Amsterdam},
  isbn      = {1876-6196},
  pages     = {1487 -- 1490},
  year      = {2009},
  language  = {en}
}
@article{WagnerWernerMiyamotoetal.2012,
  author    = {Wagner, Torsten and Werner, Frederik and Miyamoto, Ko-Ichiro and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo},
  title     = {Development and characterisation of a compact light-addressable potentiometric sensor (LAPS) based on the digital light processing (DLP) technology for flexible chemical imaging},
  series = {Sensors and Actuators B: Chemical},
  volume    = {170},
  journal   = {Sensors and Actuators B: Chemical},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0925-4005},
  doi       = {10.1016/j.snb.2010.12.003},
  pages     = {34 -- 39},
  year      = {2012},
  abstract  = {Chemical imaging systems allow the visualisation of the distribution of chemical species on the sensor surface. This work represents a new flexible approach to read out light-addressable potentiometric sensors (LAPS) with the help of a digital light processing (DLP) set-up. The DLP, known well for video projectors, consists of a mirror-array MEMS device, which allows fast and flexible generation of light patterns. With the help of these light patterns, the sensor surface of the LAPS device can be addressed. The DLP approach has several advantages compared to conventional LAPS set-ups, e.g., the spot size and the shape of the light pointer can be changed easily and no mechanical movement is necessary, which reduces the size of the set-up and increases the stability and speed of the measurement. In addition, the modulation frequency and intensity of the light beam are important parameters of the LAPS set-up. Within this work, the authors will discuss two different ways of light modulation by the DLP set-up, investigate the influence of different modulation frequencies and different light intensities as well as demonstrate the scanning capabilities of the new set-up by pH mapping on the sensor surface.},
  language  = {en}
}
@article{WagnerWernerMiyamotoetal.2010,
  author    = {Wagner, Torsten and Werner, Frederik and Miyamoto, Ko-ichiro and Ackermann, Hans-Josef and Yoshinobu, Tatsuo and Sch{\"o}ning, Michael Josef},
  title     = {FPGA-based LAPS device for the flexible design of sensing sites on functional interfaces},
  series = {Physica Status Solidi (A). 207 (2010), H. 4},
  journal   = {Physica Status Solidi (A). 207 (2010), H. 4},
  isbn      = {1862-6300},
  pages     = {844 -- 849},
  year      = {2010},
  language  = {en}
}
@article{MiyamotoWagnerYoshinobuetal.2011,
  author    = {Miyamoto, Ko-ichiro and Wagner, Torsten and Yoshinobu, Tatsuo and Kanoh, Shin`ichiro and Sch{\"o}ning, Michael Josef},
  title     = {Phase-mode LAPS and its application to chemical imaging},
  series = {Sensors and Actuators B: Chemical. 154 (2011), H. 1},
  journal   = {Sensors and Actuators B: Chemical. 154 (2011), H. 1},
  publisher = {Elsevier},
  address   = {Amsterdam},
  isbn      = {1873-3077},
  pages     = {28 -- 32},
  year      = {2011},
  language  = {en}
}
@article{MiyamotoYoshidaSakaietal.2011,
  author    = {Miyamoto, Ko-ichiro and Yoshida, Midori and Sakai, Taito and Matsuzaka, Atsushi and Wagner, Torsten and Kanoh, Sanoh and Yoshinobu, Tatsuo and Sch{\"o}ning, Michael Josef},
  title     = {Differential setup of light-addressable potentiometric sensor with an enzyme reactor in a flow channel},
  series = {Japanese Journal of Applied Physics. 50 (2011)},
  journal   = {Japanese Journal of Applied Physics. 50 (2011)},
  publisher = {Japan Society of Applied Physics},
  address   = {Bristol},
  isbn      = {0021-4922},
  pages     = {04DL08-1 -- 04DL08-5},
  year      = {2011},
  language  = {en}
}
@article{MiyamotoWagnerYoshinobuetal.2011,
  author    = {Miyamoto, Ko-ichiro and Wagner, Torsten and Yoshinobu, Tatsuo and Kanoh, Shin`ichiro and Sch{\"o}ning, Michael Josef},
  title     = {Phase-mode operation of FDM-LAPS},
  series = {Sensor letters},
  volume    = {9},
  journal   = {Sensor letters},
  number    = {2},
  publisher = {American Scientific Publishers},
  address   = {Stevenson Ranch, Calif.},
  isbn      = {1546-1971},
  pages     = {691 -- 694},
  year      = {2011},
  language  = {en}
}
@article{WagnerWernerMiyamotoetal.2011,
  author    = {Wagner, Torsten and Werner, Frederik and Miyamoto, Ko-Ichiro and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo},
  title     = {A high-density multi-point LAPS set-up using a VCSEL array and FPGA control},
  series = {Sensors and Actuators B: Chemical. 154 (2011), H. 2},
  journal   = {Sensors and Actuators B: Chemical. 154 (2011), H. 2},
  publisher = {Elsevier},
  address   = {Amsterdam},
  isbn      = {1873-3077},
  pages     = {124 -- 128},
  year      = {2011},
  language  = {en}
}
@article{MiyamotoWagnerMimuraetal.2011,
  author    = {Miyamoto, Ko-ichiro and Wagner, Torsten and Mimura, Shuhei and Kanoh, Shin{\´i}chiro and Yoshinobu, Tatsuo and Sch{\"o}ning, Michael Josef},
  title     = {Constant-phase-mode operation of the light-addressable potentiometric sensor},
  series = {Sensors and Actuators B: Chemical. 154 (2011), H. 2},
  journal   = {Sensors and Actuators B: Chemical. 154 (2011), H. 2},
  publisher = {Elsevier},
  address   = {Amsterdam},
  isbn      = {1873-3077},
  pages     = {119 -- 123},
  year      = {2011},
  language  = {en}
}
@article{WagnerMiyamotoSchoeningetal.2010,
  author    = {Wagner, Torsten and Miyamoto, Ko-ichiro and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo},
  title     = {Novel combination of digital light processing (DLP) and light-addressable potentiometric sensors (LAPS) for flexible chemical imaging},
  series = {Procedia Engineering. 5 (2010)},
  journal   = {Procedia Engineering. 5 (2010)},
  isbn      = {1877-7058},
  pages     = {520 -- 523},
  year      = {2010},
  language  = {en}
}
@article{MiyamotoKanekoMatsuoetal.2010,
  author    = {Miyamoto, Ko-ichiro and Kaneko, Kazumi and Matsuo, Akira and Wagner, Torsten and Kanoh, Shin`ichiro and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo},
  title     = {Miniaturized chemical imaging sensor system using an OLED display panel},
  series = {Procedia Engineering. 5 (2010)},
  journal   = {Procedia Engineering. 5 (2010)},
  isbn      = {1877-7058},
  pages     = {516 -- 519},
  year      = {2010},
  language  = {en}
}
@article{WagnerMiyamotoShigiharaetal.2011,
  author    = {Wagner, Torsten and Miyamoto, Ko-ichiro and Shigihara, Noriko and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo},
  title     = {Microfluidic systems with free definable sensor spots by an integrated light-addressable potentiometric sensor},
  series = {Procedia Engineering. 25 (2011)},
  journal   = {Procedia Engineering. 25 (2011)},
  publisher = {Elsevier},
  address   = {Amsterdam},
  isbn      = {1877-7058},
  pages     = {791 -- 794},
  year      = {2011},
  language  = {en}
}
@article{WernerWagnerMiyamotoetal.2011,
  author    = {Werner, Frederik and Wagner, Torsten and Miyamoto, Ko-ichiro and Yoshinobu, Tatsuo and Sch{\"o}ning, Michael Josef},
  title     = {High speed and high resolution chemical imaging based on a new type of OLED-LAPS set-up},
  series = {Procedia Engineering. 25 (2011)},
  journal   = {Procedia Engineering. 25 (2011)},
  publisher = {Elsevier},
  address   = {Amsterdam},
  isbn      = {1877-7058},
  pages     = {346 -- 349},
  year      = {2011},
  language  = {en}
}
@inproceedings{YoshinobuMiyamotoWagneretal.2012,
  author    = {Yoshinobu, Tatsuo and Miyamoto, Ko-Ichiro and Wagner, Torsten and Sch{\"o}ning, Michael Josef},
  title     = {Miniaturized and high-speed chemical imaging systems},
  series = {Nano-Biomedical Engineering 2012. Proceedings of the Tohoku University Global Centre of Excellence Programme, Sakura Hall, Tohoku University, Sendai Japan, 5 - 6 March 2012},
  booktitle = {Nano-Biomedical Engineering 2012. Proceedings of the Tohoku University Global Centre of Excellence Programme, Sakura Hall, Tohoku University, Sendai Japan, 5 - 6 March 2012},
  editor    = {Yamaguchi, Takami},
  publisher = {World Scientific},
  address   = {Singapur},
  doi       = {10.1142/9781848169067_0045},
  pages     = {386 -- 395},
  year      = {2012},
  language  = {en}
}
@article{MiyamotoKanekoMatsuoetal.2012,
  author    = {Miyamoto, Ko-ichiro and Kaneko, Kazumi and Matsuo, Akira and Wagner, Torsten and Kanoh, Shin{\´i}chiro and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo},
  title     = {Miniaturized chemical imaging sensor system using an OLED display panel},
  series = {Sensors and Actuators B: Chemical},
  volume    = {170},
  journal   = {Sensors and Actuators B: Chemical},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0925-4005},
  doi       = {10.1016/j.snb.2011.02.029},
  pages     = {82 -- 87},
  year      = {2012},
  abstract  = {The chemical imaging sensor is a semiconductor-based chemical sensor that can visualize the two-dimensional distribution of specific ions or molecules in the solution. In this study, we developed a miniaturized chemical imaging sensor system with an OLED display panel as a light source that scans the sensor plate. In the proposed configuration, the display panel is placed directly below the sensor plate and illuminates the back surface. The measured area defined by illumination can be arbitrarily customized to fit the size and the shape of the sample to be measured. The waveform of the generated photocurrent, the current-voltage characteristics and the pH sensitivity were investigated and pH imaging with this miniaturized system was demonstrated.},
  language  = {en}
}
@article{MiyamotoHirayamaWagneretal.2013,
  author    = {Miyamoto, Ko-ichiro and Hirayama, Yuji and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo},
  title     = {Visualization of enzymatic reaction in a microfluidic channel using chemical imaging sensor},
  series = {Electrochimica acta},
  journal   = {Electrochimica acta},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1873-3859 (E-Journal); 0013-4686 (Print)},
  pages     = {Publ. online},
  year      = {2013},
  language  = {en}
}
@article{MiyamotoItabashiWagneretal.2014,
  author    = {Miyamoto, Ko-ichiro and Itabashi, Akinori and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo},
  title     = {High-speed chemical imaging inside a microfluidic channel},
  series = {Sensors and actuators. B: Chemical},
  volume    = {194},
  journal   = {Sensors and actuators. B: Chemical},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1873-3077 (E-Journal); 0925-4005 (Print)},
  doi       = {10.1016/j.snb.2013.12.090},
  pages     = {521 -- 527},
  year      = {2014},
  abstract  = {In this study, a high-speed chemical imaging system was developed for visualization of the interior of a microfluidic channel. A microfluidic channel was constructed on the sensor surface of the light-addressable potentiometric sensor (LAPS), on which the ion concentrations could be measured in parallel at up to 64 points illuminated by optical fibers. The temporal change of pH distribution inside the microfluidic channel was recorded at a maximum rate of 100 frames per second (fps). The high frame rate allowed visualization of moving interfaces and plugs in the channel even at a flow velocity of 111 mm/s, which suggests the feasibility of plug-based microfluidic devices for flow-injection analysis (FIA).},
  language  = {en}
}
@article{GuoSekiMiyamotoetal.2014,
  author    = {Guo, Yuanyuan and Seki, Kosuke and Miyamoto, Ko-ichiro and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo},
  title     = {Novel photoexcitation method for light-addressable potentiometric sensor with higher spatial resolution},
  series = {Applied physics express : APEX},
  volume    = {7},
  journal   = {Applied physics express : APEX},
  number    = {6},
  publisher = {IOP},
  address   = {Bristol},
  issn      = {1882-0786 (E-Journa); 1882-0778 (Print)},
  doi       = {10.7567/APEX.7.067301},
  pages     = {067301-4},
  year      = {2014},
  abstract  = {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.},
  language  = {en}
}
@article{GuoMiyamotoWagneretal.2014,
  author    = {Guo, Yuanyuan and Miyamoto, Ko-ichiro and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo},
  title     = {Theoretical study and simulation of light-addressable potentiometric sensors},
  series = {Physica status solidi (A) : applications and materials},
  volume    = {211},
  journal   = {Physica status solidi (A) : applications and materials},
  number    = {6},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {0031-8965},
  doi       = {10.1002/pssa.201330354},
  pages     = {1467 -- 1472},
  year      = {2014},
  abstract  = {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.},
  language  = {en}
}
@article{GuoMiyamotoWagneretal.2014,
  author    = {Guo, Yuanyuan and Miyamoto, Ko-ichiro and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo},
  title     = {Device simulation of the light-addressable potentiometric sensor for the investigation of the spatial resolution},
  series = {Sensors and actuators B: Chemical},
  volume    = {204},
  journal   = {Sensors and actuators B: Chemical},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1873-3077 (E-Journal); 0925-4005 (Print)},
  doi       = {10.1016/j.snb.2014.08.016},
  pages     = {659 -- 665},
  year      = {2014},
  abstract  = {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.},
  language  = {en}
}
@article{YoshinobuMiyamotoWagneretal.2015,
  author    = {Yoshinobu, Tatsuo and Miyamoto, Ko-ichiro and Wagner, Torsten and Sch{\"o}ning, Michael Josef},
  title     = {Recent developments of chemical imaging sensor systems based on the principle of the light-addressable potentiometric sensor},
  series = {Sensors and actuators B: Chemical},
  volume    = {207, Part B},
  journal   = {Sensors and actuators B: Chemical},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1873-3077 (E-Journal); 0925-4005 (Print)},
  doi       = {10.1016/j.snb.2014.09.002},
  pages     = {926 -- 932},
  year      = {2015},
  abstract  = {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.},
  language  = {en}
}
@article{GuoSekiMiyamotoetal.2014,
  author    = {Guo, Yuanyuan and Seki, Kosuke and Miyamoto, Ko-ichiro and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo},
  title     = {Device simulation of the light-addressable potentiometric sensor with a novel photoexcitation method for a higher spatial resolution},
  series = {Procedia Engineering},
  volume    = {87},
  journal   = {Procedia Engineering},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1877-7058},
  doi       = {10.1016/j.proeng.2014.11.369},
  pages     = {456 -- 459},
  year      = {2014},
  abstract  = {A novel photoexcitation method for the light-addressable potentiometric sensor (LAPS) realized a higher spatial resolution of chemical imaging. In this method, a modulated light probe, which generates the alternating photocurrent signal, is surrounded by a ring of constant light, which suppresses the lateral diffusion of photocarriers by enhancing recombination. A device simulation verified that a higher spatial resolution could be obtained by adjusting the gap between the modulated and constant light. It was also found that a higher intensity and a longer wavelength of constant light was more effective. However, there exists a tradeoff between the spatial resolution and the amplitude of the photocurrent, and thus, the signal-to-noise ratio. A tilted incidence of constant light was applied, which could achieve even higher resolution with a smaller loss of photocurrent.},
  language  = {en}
}
@article{MiyamotoBingWagneretal.2015,
  author    = {Miyamoto, Ko-ichiro and Bing, Yu and Wagner, Torsten and Yoshinobu, Tatsuo and Sch{\"o}ning, Michael Josef},
  title     = {Visualization of Defects on a Cultured Cell Layer by Utilizing Chemical Imaging Sensor},
  series = {Procedia Engineering},
  volume    = {120},
  journal   = {Procedia Engineering},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1877-7058},
  doi       = {10.1016/j.proeng.2015.08.806},
  pages     = {936 -- 939},
  year      = {2015},
  abstract  = {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.},
  language  = {en}
}
@article{MiyamotoYuIsodaetal.2016,
  author    = {Miyamoto, Ko-ichiro and Yu, Bing and Isoda, Hiroko and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo},
  title     = {Visualization of the recovery process of defects in a cultured cell layer by chemical imaging sensor},
  series = {Sensors and Actuators B: Chemical},
  volume    = {236},
  journal   = {Sensors and Actuators B: Chemical},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0925-4005},
  doi       = {10.1016/j.snb.2016.04.018},
  pages     = {965 -- 969},
  year      = {2016},
  abstract  = {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.},
  language  = {de}
}
@article{WagnerVornholtWerneretal.2016,
  author    = {Wagner, Torsten and Vornholt, Wolfgang and Werner, Frederik and Yoshinobu, Tatsuo and Miyamoto, Ko-Ichiro and Keusgen, Michael and Sch{\"o}ning, Michael Josef},
  title     = {Light-addressable potentiometric sensor (LAPS) combined with magnetic beads for pharmaceutical screening},
  series = {Physics in medicine},
  volume    = {2016},
  journal   = {Physics in medicine},
  number    = {1},
  issn      = {2352-4510},
  doi       = {10.1016/j.phmed.2016.03.001},
  pages     = {2 -- 7},
  year      = {2016},
  abstract  = {The light-addressable potentiometric sensor (LAPS) has the unique feature to address different regions of a sensor surface without the need of complex structures. Measurements at different locations on the sensor surface can be performed in a common analyte solution, which distinctly simplifies the fluidic set-up. However, the measurement in a single analyte chamber prevents the application of different drugs or different concentrations of a drug to each measurement spot at the same time as in the case of multi-reservoir-based set-ups. In this work, the authors designed a LAPS-based set-up for cell culture screening that utilises magnetic beads loaded with the endotoxin (lipopolysaccharides, LPS), to generate a spatially distributed gradient of analyte concentration. Different external magnetic fields can be adjusted to move the magnetic beads loaded with a specific drug within the measurement cell. By recording the metabolic activities of a cell layer cultured on top of the LAPS surface, this work shows the possibility to apply different concentrations of a sample along the LAPS measurement spots within a common analyte solution.},
  language  = {en}
}
@article{MiyamotoSatoAbeetal.2016,
  author    = {Miyamoto, Ko-Ichiro and Sato, Takuya and Abe, Minami and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo},
  title     = {Light-addressable potentiometric sensor as a sensing element in plug-based microfluidic devices},
  series = {Micromachines},
  volume    = {7},
  journal   = {Micromachines},
  number    = {7},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2072-666X},
  doi       = {10.3390/mi7070111},
  pages     = {111},
  year      = {2016},
  abstract  = {A plug-based microfluidic system based on the principle of the light-addressable potentiometric sensor (LAPS) is proposed. The LAPS is a semiconductor-based chemical sensor, which has a free addressability of the measurement point on the sensing surface. By combining a microfluidic device and LAPS, ion sensing can be performed anywhere inside the microfluidic channel. In this study, the sample solution to be measured was introduced into the channel in a form of a plug with a volume in the range of microliters. Taking advantage of the light-addressability, the position of the plug could be monitored and pneumatically controlled. With the developed system, the pH value of a plug with a volume down to 400 nL could be measured. As an example of plug-based operation, two plugs were merged in the channel, and the pH change was detected by differential measurement.},
  language  = {en}
}
@article{YoshinobuMiyamotoWerneretal.2017,
  author    = {Yoshinobu, Tatsuo and Miyamoto, Ko-ichiro and Werner, Frederik and Poghossian, Arshak and Wagner, Torsten and Sch{\"o}ning, Michael Josef},
  title     = {Light-addressable potentiometric sensors for quantitative spatial imaging of chemical species},
  series = {Annual Review of Analytical Chemistry},
  volume    = {10},
  journal   = {Annual Review of Analytical Chemistry},
  publisher = {Annual Reviews},
  address   = {Palo Alto, Calif.},
  issn      = {1936-1327},
  doi       = {10.1146/annurev-anchem-061516-045158},
  pages     = {225 -- 246},
  year      = {2017},
  abstract  = {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.},
  language  = {en}
}
@article{MiyamotoHayashiSakamotoetal.2017,
  author    = {Miyamoto, Ko-ichiro and Hayashi, Kosuke and Sakamoto, Azuma and Werner, Frederik and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo},
  title     = {A high-Q resonance-mode measurement of EIS capacitive sensor by elimination of series resistance},
  series = {Sensor and Actuators B: Chemical},
  volume    = {248},
  journal   = {Sensor and Actuators B: Chemical},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0925-4005},
  doi       = {10.1016/j.snb.2017.03.002},
  pages     = {1006 -- 1010},
  year      = {2017},
  abstract  = {An EIS capacitive sensor is a semiconductor-based potentiometric sensor, which is sensitive to the ion concentration or pH value of the solution in contact with the sensing surface. To detect a small change in the ion concentration or pH, a small capacitance change must be detected. Recently, a resonance-mode measurement was proposed, in which an inductor was connected to the EIS capacitive sensor and the resonant frequency was correlated with the pH value. In this study, the Q factor of the resonant circuit was enhanced by canceling the internal resistance of the reference electrode and the internal resistance of the inductor coil with the help of a bypass capacitor and a negative impedance converter, respectively. 1\% variation of the signal in the developed system corresponded to a pH change of 3.93 mpH, which was about 1/12 of the conventional method, suggesting a better performance in detection of a small pH change.},
  language  = {en}
}
@article{WernerMiyamotoWagneretal.2017,
  author    = {Werner, Frederik and Miyamoto, Ko-ichiro and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo},
  title     = {Lateral resolution enhancement of pulse-driven light-addressable potentiometric sensor},
  series = {Sensor and Actuators B: Chemical},
  volume    = {248},
  journal   = {Sensor and Actuators B: Chemical},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0925-4005},
  doi       = {10.1016/j.snb.2017.02.057},
  pages     = {961 -- 965},
  year      = {2017},
  abstract  = {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.},
  language  = {en}
}
@inproceedings{MiyamotoSutoWerneretal.2017,
  author    = {Miyamoto, Ko-ichiro and Suto, Takeyuki and Werner, Frederik and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo},
  title     = {Restraining the Diffusion of Photocarriers to Improve the Spatial Resolution of the Chemical Imaging Sensor},
  series = {MDPI Proceedings},
  volume    = {1},
  booktitle = {MDPI Proceedings},
  number    = {4},
  doi       = {10.3390/proceedings1040477},
  pages     = {4 Seiten},
  year      = {2017},
  language  = {en}
}
@incollection{YoshinobuKrauseMiyamotoetal.2018,
  author    = {Yoshinobu, Tatsuo and Krause, Steffi and Miyamoto, Ko-ichiro and Werner, Frederik and Poghossian, Arshak and Wagner, Torsten and Sch{\"o}ning, Michael Josef},
  title     = {(Bio-)chemical Sensing and Imaging by LAPS and SPIM},
  series = {Label-free biosensing: advanced materials, devices and applications},
  booktitle = {Label-free biosensing: advanced materials, devices and applications},
  publisher = {Springer},
  address   = {Cham},
  isbn      = {978-3-319-75219-8},
  pages     = {103 -- 132},
  year      = {2018},
  abstract  = {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.},
  language  = {en}
}
@article{ItabashiKosakaMiyamotoetal.2013,
  author    = {Itabashi, Akinori and Kosaka, Naoki and Miyamoto, Ko-ichiro and Wagner, Torsten and Sch{\"o}ning, Michael Josef},
  title     = {High-speed chemical imaging system based on front-side-illuminated LAPS},
  series = {Sensors and actuators B: Chemical},
  volume    = {182},
  journal   = {Sensors and actuators B: Chemical},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1873-3077},
  doi       = {10.1016/j.snb.2013.03.016},
  pages     = {315 -- 321},
  year      = {2013},
  abstract  = {The chemical imaging sensor is a semiconductor-based chemical sensor that can visualize the spatial distribution of specific ions on the sensing surface. The conventional chemical imaging system based on the light-addressable potentiometric sensor (LAPS), however, required a long time to obtain a chemical image, due to the slow mechanical scan of a single light beam. For high-speed imaging, a plurality of light beams modulated at different frequencies can be employed to measure the ion concentrations simultaneously at different locations on the sensor plate by frequency division multiplex (FDM). However, the conventional measurement geometry of back-side illumination limited the bandwidth of the modulation frequency required for FDM measurement, because of the low-pass filtering characteristics of carrier diffusion in the Si substrate. In this study, a high-speed chemical imaging system based on front-side-illuminated LAPS was developed, which achieved high-speed spatiotemporal recording of pH change at a rate of 70 frames per second.},
  language  = {en}
}
@article{MiyamotoIchimuraWagneretal.2013,
  author    = {Miyamoto, Ko-ichiro and Ichimura, Hiroki and Wagner, Torsten and Sch{\"o}ning, Michael Josef and Yoshinobu, Tatsuo},
  title     = {Chemical imaging of the concentration profile of ion diffusion in a microfluidic channel},
  series = {Sensors and actuators. B: Chemical},
  volume    = {189},
  journal   = {Sensors and actuators. B: Chemical},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1873-3077 (E-Journal); 0925-4005 (Print)},
  doi       = {10.1016/j.snb.2013.04.057},
  pages     = {240 -- 245},
  year      = {2013},
  abstract  = {The chemical imaging sensor is a device to visualize the spatial distribution of chemical species based on the principle of LAPS (light-addressable potentiometric sensor), which is a field-effect chemical sensor based on semiconductor. In this study, the chemical imaging sensor has been applied to investigate the ion profile of laminar flows in a microfluidic channel. The chemical images (pH maps) were collected in a Y-shaped microfluidic channel while injecting HCl and NaCl solutions into two branches. From the chemical images, it was clearly observed that the injected solutions formed laminar flows in the channel. In addition, ion diffusion across the laminar flows was observed, and the diffusion coefficient could be derived by fitting the pH profiles to the Fick's equation.},
  language  = {en}
}
@article{YoshinobuMiyamotoWagneretal.2024,
  author    = {Yoshinobu, Tatsuo and Miyamoto, Ko-ichiro and Wagner, Torsten and Sch{\"o}ning, Michael Josef},
  title     = {Field-effect sensors combined with the scanned light pulse technique: from artificial olfactory images to chemical imaging technologies},
  series = {Chemosensors},
  volume    = {12},
  journal   = {Chemosensors},
  number    = {2},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2227-9040},
  doi       = {10.3390/chemosensors12020020},
  pages     = {Artikel 20},
  year      = {2024},
  abstract  = {The artificial olfactory image was proposed by Lundstr{\"o}m 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.},
  language  = {en}
}