Masahiro Akiya

Development of a vitamin-protein sensor based on carbon nanotube hybrid materials

A bionanosensor consisting of a field effect transistor chip and containing a mixture of poly(ethylene glycol)-grafted single-walled carbon nanotubes (SWCNTs) and SWCNTs modified with a protein (avidin) which binds with a specific vitamin (biotin) is developed. An increase in impedance due to biotin-avidin binding is observed when biotin is injected, while the injection of other vitamins resulted in a decrease in impedance. This bionanosensor reacts quickly (∼60s); in addition, the impedance recovers almost to its initial value when the bionanosensor is washed with distilled water; thus, the vitamins do not bind directly with the SWCNTs.

Chemical Modification of Carbon Nanotube Based Bio-Nanosensor by Plasma Activation

Chemical modification with plasma ion irradiation (plasma activation) is demonstrated on a bio-nanosensor based on poly(ethylene glycol)-grafted single-walled carbon nanotubes (PEG-SWNTs). By X-ray photoelectron spectroscopy (XPS) analysis, peaks that correspond to CO and COOH radicals are observed. In addition, the evaluation of the characteristic responses of the bio-nanosensor using a bovine serum albumin (BSA) antigen or oligonucleotide reveals an increase in impedance due to an antigen–antibody reaction or oligonucleotide hybridization. From these results, the bio-nanosensor is found to react with a short response time (60 s).

Compatible High and Low Voltage CMOS Devices Using SIMOX Technology

New type high and low voltage CMOS buried channel devices are described, which are applied to a current mirror and an operational amplifier using SIMOX technology. In the MOS current mirrors, a 0.5% matching error rate was obtained in a 10 µA drain current without any compensation circuits. In the two stage operational amplifier, an open loop voltage gain of 60 dB was obtained with a ±5 V supply.

Fat Liquefaction of Adipose Tissue Using Atmospheric-Pressure Plasma Irradiation

The liquefaction of fat in adipose tissue for potential medical applications was achieved by direct irradiation using an atmospheric-pressure plasma source and a catheter-type apparatus. When fat was irradiated with plasma generated from a catheter tip, it was liquefied through ozonolysis, although little production and diffusion of ozone originating from the collision/ionization of gas molecules was observed in preliminary experiments. Furthermore, surface damage to fat cells, such as thermal carbonization or electric shock injuries, was not observed.

Measurement of Contractile Activity in Small Animal's Digestive Organ by Carbon Nanotube-Based Force Transducer

A carbon nanotube (CNT)-based force transducer designed to be embedded in the body of a live animal was fabricated and implanted into the stomach of a rat omit to measure contractile movement. The transducer comprised dispersed poly(ethylene glycol)-grafted multiwalled CNTs applied to a comb-like Au-electrode formed on a poly(dimethylsiloxane) sheet. The implanted rat was injected with acetylcholine to induce muscular contractions and changes in the resistance of the transducer were measured. Such changes arise owing to strain in the CNT network upon distortion. The measured resistance change was found to be proportional to the concentration of injected acetylcholine.