Naoto Usami

• Doctor of Engineering
• Professor (Assistant) at Japan Aerospace Exploration Agency

Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are...

We present a self-deformable flexible tweezer capable of simultaneous mechanical handling and electrical measurements. The tweezer has a soft cantilever with the dimensions 2 mm $\times8$ mm $\times $ 75- $100~\mu \text{m}$ , and undergoes self-deformation. The device is shown to be successfully capable of detecting electrical signals by gentl...

We have realized an infrared (IR) photodiode with silicon for the future beyond-VLSI photonics. Colloidal quantum dot (CQD) integration with Si is a simple process. We previously reported a PbS CQD/ZnO/Si hybrid IR photodiode. The device had an absorption peak at 1230 nm. To improve the quantum efficiency, we investigated the dose levels of Si subs...

Widespread research is being conducted on computational materials. The challenge for the realization of computational materials is how to weave computers into everyday objects consisting of various shapes and form factors. One idea to achieve this vision is to build physical computational particles that can cooperatively communicate among others an...

Investigating heterointerfaces with test structures is crucial for fabricating electronic and photonic devices. Recently, we proposed and developed a PbS colloidal quantum dot/ZnO/Si hybrid infrared detector for infrared-sensitive optoelectronic devices on silicon-based large-scale integrated circuits. The conventional circular transfer length meth...

We propose and demonstrate a drop-in test structure to visualize and measure the residual stress in the conformally deposited film. For reliable device process of microsystems (such as 3-D MEMS), the residual stress must be controlled through quantitative evaluation at each deposition step. A small drop-in test structure placed near the main sample...

Miniaturized mobile microrobots have opened new applications from biomedical to environmental fields. Among various types of microrobots, recent progress on highly performing planar type microrobots could offer a good compromise between the manufacturability and the functionality promising for practical applications. The remaining challenges are to...

We propose a drop-in test structure chip to evaluate residual stress. The structure was applied to evaluate supercritical fluid deposition (SCFD) Cu film over atomic layer deposition (ALD) Ru/TiO 2 film. In an early development stage of such emerging technology, researchers make experiments with a small sample chip in a small chamber. Small chips m...

This paper reports an area-selective supercritical fluid deposition (SCFD) of Cu with supercritical CO2 and H2 reductant. We demonstrated an area-selective Cu SCFD on TiN pre-patterned over a SiO2 underlayer on Si substrate. Atomic force microscopy and Auger electron spectroscopy were employed to characterize the fabricated samples. Several SCFD ex...

In this article, we propose a device with multiple small pores, which are locally integrated with individual electrodes. The application is particle measurement using Coulter's method, using the integrated local electrode on each pore. Coulter's particle counter can achieve high resolution measurement; however, the method had sensitivity and throug...

Near-infrared detectors by silicon based devices with large scale integration are very attractive for secure applications about image sensors. Beyond the silicon bandgap, we focus on PbS colloidal quantum dots (CQDs) and silicon integration. In this paper, we investigated fabrication processes of PbS CQDs and silicon hybrid IR detector. Temperature...

Quaternion neural networks (QNNs) achieve high accuracy in polarimetric synthetic aperture radar classification for various observation data by working in Poincare-sphere-parameter space. The high performance arises from the good generalization characteristics realized by a QNN as 3-D rotation as well as amplification/attenuation, which is in good...

This paper presents a versatile chip-level wireless driving method for microelectromechanical system (MEMS) actuators. A MEMS actuator is integrated as an electrical component of a coupled LCR resonant circuit, and it rectifies the energy sent through an ultrahigh-frequency (UHF) radio frequency (RF) wave. Two types of actuators were remotely drive...

We propose a wideband reconfigurable circular-polarized single-port antenna to realize high-density linear integration for use in ground penetrating radars. We switch PIN diodes at a T-shaped probe to change its polarization. The forward- and reverse-biased probes work in cooperation to generate circular polarization. Experiments demonstrate the wo...

Polarimetric synthetic aperture radar is expected to distinguish wet snow from bare ground. However, since both of them show the surface scattering, that is sensitive to incidence angle, it often fails in the distinction in mountainous areas. In this paper, we propose an adaptive distinction method by using quaternion neural networks. In the ALOS-2...

DESPATCH (DEep SPace Amateur Troubadour's CHallenge) is the second spacecraft in the Art and Satellite (ARTSAT) project. The size of the DESPATCH is 50×50×50 cm and the total mass is about 33 kg. DESPATCH consists of a sculpture (made by 3D printer) and other structural elements made of aluminum. The mass of this sculpture is about 15 kg and it occ...

ARTSAT-2 DESPATCH is developed by ARTSAT project, which consists of voluntary members in The University of Tokyo and Tama Art University. DESPATCH, 50cm cube in size with a mass of 33 kg has a spiral-shaped 3D-printed sculpture as the main structure of the spacecraft. It is the world’s first spacecraft whose body itself is an artwork. In addition,...

Reconfigurable circular-polarized antennas are expected to improve ground penetrating radars (GPRs) utilizing high-density arrayed and complexly switched antennas. This report presents a wideband reconfigurable circular-polarized single-feed antenna. It comprises a waveguide and a T-shaped probe. We switch its polarization type by changing the bias...