Takahito Ono 교수

Ultrathin single-crystalline silicon cantilevers with a thickness of 170 nm as a resonating sensor are applied to mass sensing. The hydrogen storage capacity of a small amount of carbon nanotubes (CNTs), which were mounted on an ultrathin resonator by a manipulator, is measured from the resonant frequency change. The resonator is annealed in ultrahigh vacuum to clean the surface and increase the quality factor, and exposed to oxygen gas to oxidize the surface for long-term stability. The resonat

Very weak light emission due to micro-discharges in the micro-gap of an electrostatic actuator under a high electric field can be imaged using a highly sensitive CCD camera. In this paper, we focus, in particular, on the relation between the micro-discharge and the electric field breakdown. Micro-discharges attributed to local breakdown is observed even if the electric field strength is below the breakdown threshold. The observations of the micro-discharge give important information on the irreg

Using a scanning tunneling microscope (STM), Si nanowires were grown by applying a voltage at a constant current between a Si substrate and a gold STM tip. Silicon atoms were deposited onto a gold tip by field evaporation. The field evaporation rate of silicon atoms was activated by heating the substrate. Silicon nanowire was grown on the gold tip at a substrate temperature of 700 °C. Nanowires could not be grown on a clean tungsten tip when using a gold-free Si substrate. The presence of gold a

A micro tool for evaluating thermoelectric properties of low-dimensional materials is developed. It is expected that a one-dimensional thermoelectric material exhibits superior thermoelectric properties and low thermal conductivity due to its inherent nanoscale structure. By using these superior properties, high efficient thermoelectric power transformation devices may be realized. In this study, we developed micro instrumentation fabricated by micromachining for the characterization of thermoel

Theoretical modeling and experimental validation of a thermoelectric generator (TEG) integrated with a phase change material (PCM) are reported in this paper. The proposed device converts the daily ambient temperature variations into a temperature difference on the TEG using a PCM, thus temperature variations can produce electrical energy. Thermal modeling is developed and compared with the experimental result. The developed system is evaluated by using a temperature-controlled oven as well as a

This paper reports on mass sensing with 33 nm thick single-crystalline cantilevers by a double-beam laser Doppler vibrometer. The resonant frequency of an oscillating thin cantilever beam is very sensitive to a loaded mass. However, the drift of the resonance, due to gas adsorption and mechanical instability, limits the minimum detectable mass in general. Two cantilevers for sensing and its reference will compensate their influences. Two cantilevers were made to self-oscillate by electrostatic a

The influence of an electric field on carbon nanotube (CNT) growth using hot-filament chemical vapour deposition is investigated. Acetylene (C2H2) gas diluted with hydrogen is used as the source gas for the growth of CNTs, and a bias voltage of -300 V is applied to the sample stage during growth. The silicon substrate onto which the CNT is grown is prepared by sputtering a thin catalysed metal (Ni) film onto the surface, and the CNT is selectively grown from the tip of a silicon protrusion on th

In this article, we demonstrated magnetic and optical force measurements using an ultrathin silicon cantilever down to 20 nm or 50 nm in thickness. The cantilever was heated in an ultrahigh vacuum for enhancing the Q factor and a magnetic particle was mounted at the end of the cantilever using a manipulator. The vibration was measured by a laser Doppler vibrometer and its signal was fed to an opposed metal electrode for electrostatic self-oscillation. An application of a magnetic field with a co

This article demonstrates a new approach using a thermoelectric generator (TEG), which converts thermal energy from ambient temperature fluctuations into electricity for the power source of portable devices. Using TEGs with heat storage material on one side of the TEG, a temperature difference can be created at both sides of the TEG from ambient temperature variations. In this work, the electric power generation and its storage to a capacitor are evaluated for the TEG-heat storage device. Two ki