In this study, we proposed a new sensing method using a special SPR chip on which microstructures are fabricated, and
performed a principle confirmation of the sensing feasibility using this chip. We examined a fabrication method of micro
structures on the SPR chip that has a filter effect by the pillar structure, which can filter the target substance reaching to
the detection area of SPR sensing. In order to confirm the filter effect of the micro structure on the SPR chip, we
performed the principle confirmation experiment of the SPR sensing system using the fine particles. Next, in order to
adapt to the biological molecules measurement, we performed the experiment using yeast cells and demonstrated the
filter effect of this chip with the micro structure.
This paper describes a new fabrication process of a micro elliptical collimator lens to form a beam shape for LD(Laser Diode), and the evaluation results of the optical characteristic for this lens. Beam shape of LD is an ellipse because divergent light angle is different between horizontal and vertical direction, which increases a coupling loss with an optical fiber. In this presentation, we propose the lens to form the divergent light of an elliptical beam shape to the collimated light of a circular beam shape. This lens makes it possible to reduce the coupling loss with the optical fiber. For this purpose, we designed one lens, which has different curvature radiuses between incident and output surfaces. In the incident surface, the divergent light is formed to the convergent light, and in the output surface, the convergent light is formed to the collimated light. We simulated the optical characteristic of this lens, and designed for various parameters. In order to fabricate this lens, we propose a new process using a chemically absorbed monomolecular layer, which has an excellent hydrophobic property. This layer is patterned and deposited by a photolithographic technique. Next, we drop a UV(Ultra Violet) cure material on the hydrophilic area, as the result, we can fabricate a micro elliptical lens shape. The curvature radius of this lens can be controlled by the amount of a dropped UV cure material and an elliptical pattern size in horizontal and vertical direction. The formed lens shapes are transferred by the electro-plating and then the micro dies are fabricated. And they are used for molding the plastic lens.
Recently DNA molecules have been focused on as electronic elements in the field of nanometer-scale electronics. One of the fundamental issues in this research area is the development of methods to measure accurately an electrical conductivity of DNA wire. The DNA tweezers we have recently developed have a great advantage of measuring
the electrical current passing through DNA wire. In this paper, we investigated the electric conduction of lambda DNA molecules covered with Pd colloids using micromachined DNA tweezers that has a pair of opposing probes for retrieving DNA molecules. The molecules were retrieved from a solution containing lambda DNA by applying RF power between the probes in the solution. The retrieved molecules were then soaked in a colloidal solution containing cationic Pd particles,
which results in a DNA-Pd wire bridged between the tweezer probes. Current-voltage curves for the DNA-Pd wire can be measured between the DNA tweezers probes, and the resistivity of the DNA-Pd wire was approximately 74 Ωcm. We found through an observation by a scanning transmission electron microscope (STEM) that the surface of the wire was covered by Pd particles closely. We also measured the piezoresistance through a change in the distance between Pd
particles on a DNA-Pd wire using the DNA tweezers.
Recently, there are a lot of studies on the micro motors using an electrostatic actuator as the driving force in the micro electro mechanical systems (MEMS) field. However, the electrostatic actuator has a problem concerning the precise actuation control. In the conventional researches, the rotary type electrostatic actuators have been reported, but the rotation angle has not been precisely controlled in the actuators. This paper describes a new micro motor by a rotary type scratch drive actuator (SDA) with a Poly-Si scale to measure the rotation angle based on the MEMS technology. In this study, we make it possible to measure the rotation angle of th rotary type SDA motor by a fiber type micro encoder. For this purpose,
we formed the Poly-Si scale around the outside of the micro SDA motor, and achieved a reflection type optical fiber micro encoder. In this presentation, we describe the fabrication process for this device and the evaluation results of the optical characteristic of the fiber type micro encoder.
This paper proposes a new method for detecting label-free T4-DNA molecules using a Surface Plasmon Resonance (SPR<sup>1,2</sup>) technique on a gold thin film. We used a solution that dissolved T4-DNA molecules in pure water, and examined the relation between DNA concentration change and SPR angle change in the solution. As the result, it was confirmed that the SPR angle change increased with the increase of the DNA concentration change. Therefore, it was feasible to detect the DNA concentration change using the SPR technique. Further, in order to examine to detect a single DNA molecule, we calculated the area that a single DNA molecule would occupy in SPR area, and we examined to focus the beam of the SPR device at the area. However, it is difficult to focus the diameter of the spot within 500um because ofn the size of a light source and the incident angle of the light. Therefore, we tried to fabricate the SPR chip in which SPR area is narrowed that has the same effect as focusing the beam. In order to narrow the SPR area, we decreased the area of gold thin film in this chip, and also, in order to reflect a light from only the area of gold thin film, the area without a gold thin film was micro-machined to make it unevenness for the reduction of a light reflection. By the above-mentioned method, we examined the possibility to detect the label-free DNA molecule using the SPR technique.
A variable optical attenuator (VOA) is a tunable device that can control the amount of the attenuation of the laser power in the optical communication systems. We proposed a new construction of the VOA composed of lenses and fibers and micro-actuators, which are very simple and easy to assemble. By the constructed devices, the good optical characteristics such as an insertion loss, a wavelength dependency and dynamic range are confirmed experimentally.
We have succeeded in retrieval of λ-DNA molecules (DNAs) with micromachined DNA tweezers and reported the retrieved DNAs are insulating. Two kinds of fabrication methods of narrow gap DNA tweezers are demonstrated. In order to form a pair of opposing sharp probes with nano meter size gap, an etch stop mechanism was examined for etching process by monitoring current between the probes. In a wet etching method, a free-standing Si bridge structure having a small cross-sectional portion is firstly formed and dipped into a small drop of KOH solution which was cooled using a peltiert device. Then an AC voltage is applied through the structure, which heats the portion of the bridge dominantly as well as the surrounding KOH solution. As the result, the local Si etching by the KOH solution lasts as long as the structure is bridged. Using this method, we could fabricate 50nm-gap DNA tweezers. In a dry etching, we also succeeded in narrow gap fabrication by etching a free-standing Si bridge structure in the probes tip of DNA tweezers using fluorine radical. The tweezers fabricated by dry etching have a pair of opposing probes with 120nm-gap.