Shoko Takenaga

Charge Accumulation Type Hydrogen Ion Image Sensor with High pH Resolution

We propose a charge transfer type ion image sensor operated using a charge accumulation technique that accumulates the output signal and integrates it temporally. This technique is expected to image hydrogen ion distributions with a high signal-to-noise (S/N) ratio. The sensor was fabricated using large-scale integration technology, so that its size was very compact, and its specialized charge transfer characteristics allowed it to amplify the signal without any external amplification. The sensor noise was independent of the sensing area size, and the noise power was determined by the noise of the source follower circuit. In 5 accumulation cycles, the S/N ratio increased by √5 times and the pH-referred noise, which indicates the pH sensor resolution, was reduced from 0.09 to 0.06 pH. The sensor effectively obtained a real-time image of the hydrogen ion distribution in a solution with a resolution of pH 0.1, which would not be possible without charge accumulation.

Label-Free Acetylcholine Image Sensor Based on Charge Transfer Technology for Biological Phenomenon Tracking

A 32 ×32 charge-transfer enzyme-type acetylcholine (ACh) image sensor array was produced for label-free tracking of images of ACh distribution and its performance in repeatable measurements without enzyme deactivation was examined. The proposed sensor was based on a charge-transfer-type pH image sensor, which was modified using an enzyme membrane (acetylcholine esterase, AChE) for each pixel. The ACh image sensor detected hydrogen ions generated by the ACh–AChE reaction. A polyion complex membrane composed of poly(L-lysine) and poly(4-styrenesulfonate) was used to immobilize the enzyme on the sensor. The improved uniformity and adhesion of the polyion complex membrane were evaluated in this study. As a result, temporal and spatial fluctuations of the ACh image sensor were successfully minimized using this approach. The sensitivity of the sensor was 4.2 mV/mM, and its detection limit was 20 µM. In five repeated measurements, the repeatability was 8.8%.

Label-free real time imaging of neural communication using acetylcholine image sensor

Release of acetylcholine (ACh) by a local K+ ion stimulation to neurons was successfully imaged using charge transfer type label-free ACh image sensor. In the non-stimulation area, the ACh release from the neurons was observed and the released ACh gradually diffused with time. These data suggest that the images of ACh release induced by local depolarization are involved in the propagation signals mediated by the neurotransmission at the nerve terminals. This report demonstrates the prospect for the label-free neural communication imaging for the first time.

Analysis of enzyme-immobilized polyion complex membrane on label free acetylcholine ion image sensor

32 × 32 acetylcholine (ACh) image sensor was successfully obtained for a real time ACh distribution image. In this work, the sensor using optimized enzyme-immobilized polyion complex membrane composed of poly-L-lysine and poly (sodium 4-styrensulfonate) was measured with better stability and repeatability. The optimized polyion complex membrane was fabricated with better adhesion to the sensor. As a result, the noise was reduced and the sensor can be measured repeatedly unless the enzyme is inactivated and the membrane is removed.

Two-dimensional label-free acetylcholine image sensor for imaging neuronal communication

32×32 acetylcholine image sensors were successfully fabricated by using the CCD/CMOS image sensor technique, and real time imaging of acetylcholine distribution was carried out without label and a huge measurement. Acetylcholine imaging technology has a lot of potential for the early stage of Alzheimers disease, the release mechanism between terminal neurons. In addition, the proposed sensor is a very unique device due to not only determine quantity but also acquire real time imaging of behavior of biological matter. Therefore, the sensor has an infinite of possibility as a new tool in medical and biological field.

On-Line Monitoring of the Metabolic Activity of Bacteria and Eukaryotic Cells Utilizing Light-Addressable Potentiometric Sensors

On-line monitoring of the metabolic activity of eukaryotes and microorganisms can avoid [...]

Two-dimensional label-free acetylcholine image sensor based on enzyme-immobilized polyion complex membrane

32 × 32 acetylcholine (ACh) image sensors using enzyme-immobilized polyion complex membrane were successfully required real time imaging of ACh distribution with better stability and improve responsibility. Nowadays, acetylcholine imaging technology has a lot of potential for human activity analysis and localization of disease. The proposed Charge-Transfer Technique ACh Image Sensor (CTTAIS) is a very unique device due to not only determine quantity but also acquire real time imaging of behavior of biological matter without label.