Tomohiko Sugiyama

3D viewpoint selection and bilateral control for bio-micromanipulation

A need has arisen to manipulate a small biological object, such as an embryo, cell, and microbe. Bio-micromanipulation is important for biology and the bioengineering field. However, it is very difficult, since the object is very small, kept in liquid, and observed by an optical microscope. The image of the microscope is two dimensional, so it is hard to manipulate the target in 3D space. The object is fragile, so it is hard to manipulate safely. To improve the manipulation works, the authors propose the viewpoint selection method in VR space, and a bilateral control system to improve manipulation of the micro object under the microscope.

Micro tri-axial force sensor for 3D bio-micromanipulation

It is important to manipulate a biological small object, such as a cell and embryo. Three-dimensional high speed micromanipulation is needed as a fundamental technology for biology and bio-engineering application. In this paper, we focus on the contact type micromanipulation in the liquid. We designed and made a contact type micromanipulation system which has a 3-DOF narrow range positioning system on a 3-DOF wide range positioning system. We developed a micro tri-axial force sensor which can be installed near the tip of the end effector. Performance of this micro-force sensor is presented.

Production of CW High-Density Non Equilibrium Plasma in the Atmosphere Using Microgap Discharge Excited by Microwave

A new technique for cw production of high-pressure, high-density, non-equilibrium plasma is presented. Using microwave excitation at 2.45 GHz, a stable atmospheric glow discharge was sustained between two knife-edge electrodes, having a length of 10 mm and facing each other across a ~100 µm microgap. Laser Thomson scattering diagnostics indicates that the plasma density in the microgap is as high as 1.6×1015 cm-3 at a microwave power of 100 W. The optical emission of the N2 second positive band indicates that the gas temperature in the microgap is 1800 K, much lower than the electron temperature.

High Internal Quantum Efficiency Blue-Green Light-Emitting Diode with Small Efficiency Droop Fabricated on Low Dislocation Density GaN Substrate

We fabricated blue (~450 nm), blue-green (~500 nm), and green (~525 nm) light-emitting diodes (LEDs) of different dislocation densities (DD) and characterized their internal quantum efficiency (IQE). The IQE of the blue LEDs fabricated using GaN substrate exceeded 90% (DD: ~106 cm-2), however, when we used a GaN-on-sapphire substrate (DD: ~108 cm-2), IQE was limited to ~60%. Droop was reduced by use of the GaN substrate. The junction temperature of the GaN-on-sapphire substrate was found to be ~200 °C although the junction temperature of the GaN substrate was ~50 °C when a forward current of 100 A/cm2 was driven. A lowering of IQE in green LEDs to ~60% was observed, even though we used a low-dislocation-density substrate [DD: (1–2)×107 cm-2]. The junction temperature of blue-green and green LEDs was about 100 °C when a forward current of 177 A/cm2 was driven, which indicated that junction temperature is not a major factor for IQE suppression in green LEDs.

3D bio-micromanipulation (bilateral control system using micro tri-axial force sensor)

Recently, it is demanded to manipulate a small biological object, such as an embryo, cell, and microbe. Biomicromanipulation is important for biology and bioengineering fields. However, it is very difficult, since the object is very small, kept in the liquid, and observed by the optical microscope. The image of the microscope is two dimensional, so it is hard to manipulate the target in the 3D space. The object is fragile, so it is hard to manipulate safely. To improve the manipulation works, here we propose the viewpoint selection method in the VR space, and a new bilateral control system to improve manipulation of the micro object under the microscope.

Electrode Structure of Ferroelectric Electron Emitter

A novel electron emitter utilizing the characteristics of ferroelectric ceramic materials has been developed. The electron-emitting portion of the electron emitter has a unique microstructure that has a vacuum gap between the upper electrode and the surface of the ferroelectric layer. We confirmed electron emission by a three-step process that consists of (the first step) electron charge, (the second step) charge retention, and (the third step) electron emission. The asymmetric property of ferroelectric hysteresis in the process indicates the following results. In the first step, an electron charge is performed in synchrony with the polarization reversal of the ferroelectric layer. On the other hand, in the third step, the electric field in the vacuum gap advances the electron emission while the polarization reversal is performed in the ferroelectric layer.

Electron Emission from Ferroelectric Electron Emitter at Transient State of Negative Polarization Reversal

A novel electron emitter with the characteristics of ferroelectric ceramic materials has been developed. The electron-emitting portion of the electron emitter has vacuum gaps between the upper electrode and the surface of the ferroelectric layer. We confirmed that there are two types of electron emission from the electron emitter. One is considered to be the emission of the electron charge from the ferroelectric surface during a positive polarization reversal. In this paper, the characteristics and mechanism of the other type of electron emission are discussed which is expected to have high efficiency. We consider that field emission occurs as induced by the electric field concentrated in the vacuum gap transiently during a negative polarization reversal. A suitable electric conductivity of the ferroelectric surface is considered to be required for electron emission.

Reduction of efficiency droop in InGaN light-emitting diodes on low dislocation density GaN substrate

A GaN layer of 20 μm thickness grown by the liquid-phase epitaxy on c-plane sapphire was used as a template for the growth of blue light-emitting diodes (LEDs) with emission peak wavelengths of about 450 nm. As the underlying layer of the active region, an InGaN/GaN superlattice or two pairs of 100 nm undoped GaN and 20 nm GaN:Si layers on an n-type GaN:Si layer was found to be effective for reducing the forward voltage. By optimizing the multiple-quantumwell structure, LEDs having a 2.5-nm-thick InGaN well and 5-nm-thick GaN barrier exhibited the highest internal quantum efficiency (IQE) at both low and high currents. This IQE was much higher than that of LEDs on a sapphire substrate. The IQE of LEDs using the liquid-phase GaN grown on sapphire substrate exceeded more than 75% at a forward current density of over 200 A/cm2.

Safety of Carbon Dioxide Insufflation during Endoscopic Submucosal Dissection for Esophageal Squamous Cell Carcinoma

Background: Pulmonary dysfunction often accompanies esophageal squamous cell carcinoma (SCC). Aims: This study examined the use of carbon dioxide (CO2) insufflation and its safety during esophageal endoscopic submucosal dissection (ESD) while under conscious sedation. Methods: ESD using CO2 insufflation (1.4 L/min) was performed in 102 consecutive esophageal SCC patients. Patients with a forced expiratory volume of 1.0 s/forced vital capacity (FEV1.0%) < 70% or a vital capacity < 80% were defined as having pulmonary dysfunction. Transcutaneous partial pressure of CO2 (PtcCO2) was recorded before, during, and after ESD. Results: A history of smoking was found in 90 patients (88%), while 43 patients (42%) had pulmonary dysfunction. No significant differences were found between the pulmonary dysfunction and normal groups for the baseline PtcCO2 before ESD, peak PtcCO2 during ESD, and median PtcCO2 after ESD. There was a significant correlation between the PtcCO2 elevation from baseline and the ESD procedure time (r = 0.32, p < 0.01), with the correlation for the pulmonary dysfunction group much stronger (r = 0.39, p < 0.05) than that for the normal group (r = 0.30, p < 0.01). Neither of the groups exhibited any differences for either the complication incidence or the hospital stay. Conclusions: Although the use of CO2 insufflation during esophageal ESD under conscious sedation is safe with regard to the risk of complications, longer procedure times can potentially induce CO2 retention in patients with obstructive lung disease. Thus, it is necessary to both shorten the procedure times and perform CO2 monitoring.

A case of a teenage boy with eosinophilic gastroenteritis with esophageal involvement developing a hemorrhagic duodenal ulcer.

A boy in his early teens visited our hospital with chief complaints of hematemesis and tarry stools. Upper gastrointestinal endoscopy identified a hemorrhagic duodenal ulcer, for which hemostasis was performed using a clip. Proton pump inhibitor (PPI) administration diminished the ulcer but relapse occurred after PPI discontinuation. The esophagus showed concentric rings and longitudinal linear furrows considered to be characteristic of eosinophilic esophagitis. Biopsies of the duodenal ulcer and the esophagus revealed marked infiltration of eosinophils, leading to a diagnosis of eosinophilic gastroenteritis with esophageal involvement. Steroid treatment was initiated, and the duodenal ulcer and esophagitis resolved. Endoscopic findings characteristic of eosinophilic esophagitis were key to the diagnosis of eosinophilic gastroenteritis.