Biomedical subjects

Toshiro Higuchi

Publications and source records attributed to Toshiro Higuchi.

5 recordsLinked to original sources

PubMed2004

Controlled production of monodisperse double emulsions by two-step droplet breakup in microfluidic devices.

A microfluidic device having both hydrophobic and hydrophilic components is exploited for production of multiple-phase emulsions. For producing water-in-oil-in-water (W/O/W) dispersions, aqueous droplets ruptured at the upstream hydrophobic junction are enclosed within organic droplets formed at the downstream hydrophilic junction. Droplets produced at each junction could have narrow size distributions with coefficients of variation in diameter of less than 3%. Control of the flow conditions produces variations in internal/external droplet sizes and in the internal droplet number. Both W/O/W emulsions (with two types of internal droplets) and oil-in-water-in-oil emulsions were prepared by varying geometry and wettability in microchannels.

Journal Article↗

PubMed2002

Chemical reactions in microdroplets by electrostatic manipulation of droplets in liquid media.

A microchemical reaction method involving microdroplets is proposed. Microdroplets are formed in a chemically stable medium on electric panel devices. These devices are substrates which have electrode arrays or electrode dots, and its surfaces are coated by an insulating film (such as Teflon or polypropylene) to prevent discharge and electrolysis of solutions. Microdroplets can be separately manipulated by a traveling electric field, which arises on applying a sequential voltage to the electrodes. Droplets moved smoothly at 1 Hz and voltage 400 V(0-p). Reagents were then put in droplets that were collided and coalesced, resulting in chemical reactions that included alkalization of phenolphthalein and the luciferin-luciferase reaction.

Journal Article↗

PubMed2002

Droplet formation in a microchannel network.

A method is given for generating droplets in a microchannel network. With oil as the continuous phase and water as the dispersed phase, pico/nanoliter-sized water droplets can be generated in a continuous phase flow at a -junction. The channel for the dispersed phase is 100 microm wide and 100 microm deep, whereas the channel for the continuous phase is 500 microm wide and 100 microm deep. For given experimental parameters, regular-sized droplets are reproducibly formed at a uniform speed. The diameter of these droplets is controllable in the range from 100-380 microm as the flow velocity of the continuous phase is varied from 0.01 m s(-1) to 0.15 m s(-1).

Journal Article↗

PubMed2002

Sensitivity of a miniaturized touch probe sensor using PZT thin film vibrator.

In this paper, an improved touch probe sensor device for higher sensitivity and low contact force is reported. In order to improve the resolution, we have evaluated the sensitivity and fabricated a miniaturized sensor. The sensor transducer was 3 mm long and had higher resonance frequency. The resonance frequency of the vibrator was 937 kHz. Evaluated sensitivity was 1.0 x 10(-1) mV/nm. This value equals five times larger than that of a previous sensor. Miniaturization of the sensor device carried smaller vibration operation and higher sensitivity.

Journal Article↗

PubMedDate not supplied

Electrostatic tactile display with thin film slider and its application to tactile telepresentation systems.

A new electrostatic tactile display is proposed to realize compact tactile display devices that can be incorporated with virtual reality systems. The tactile display of this study consists of a thin conductive film slider with stator electrodes that excite electrostatic forces. Users of the device experience tactile texture sensations by moving the slider with their fingers. The display operates by applying two-phase cyclic voltage patterns to the electrodes. The display is incorporated into a tactile telepresentation system to realize explorations of remote surface textures with real-time tactile feedback. In the system, a PVDF tactile sensor and a DSP controller automatically generate voltage patterns to present surface texture sensations through the tactile display. A sensor, in synchronization with finger motion on the tactile display, scans a texture sample and outputs information about the sample surface. The information is processed by a DSP and fed back to the tactile display in real time. The tactile telepresentation system was evaluated in texture discrimination tests and demonstrated a 79 percent correct answer ratio. A transparent electrostatic tactile display is also reported in which the tactile display is combined with an LCD to realize a visual-tactile integrated display system.

Computer Peripherals↗