Akio Sugama

A miniature Clark-type oxygen electrode using a polyelectrolyte and its application as a glucose sensor

A miniature Clark-type oxygen electrode was fabricated by anisotropically etching silicon. A two-gold-electrode configuration was used and a double-layered gas-permeable membrane was formed directly on the electrolyte, poly(vinyl-4-ethylpyridinium bromide) in the sensitive area. These materials improved the electrodes stability in long-term storage and sterilization tolerance to a practical level. The 90% response time averaged 80 s and residual current 10%, with a good linear calibration curve. The oxygen electrode was also used to make an integrated sensor for the simultaneous determination of glucose and oxygen. The glucose sensors response time was 50-110 s, with good linearity in glucose concentrations between 56 microM and 1.1 mM at 37 degrees C, pH 7.0.

Miniature Clark-type oxygen electrode with a three-electrode configuration

Abstract A Clark-type oxygen electrode with three electrodes has been fabricated using semiconductor techniques and its characteristics compared with those of double oxygen electrodes with a similar structure. The 90% response time is 40 s, the residual current at zero oxygen concentration is less than 7%, and the linearity is good. The oxygen electrode can be used for 25 h at −0.6 V. These characteristics are affected by electrochemical crosstalk between the electrodes and are improved by varying the electrode configuration.

Development of a miniature clark-type oxygen electrode using semiconductor techniques and its improvement for practical applications

Abstract A disposable minature Clark-type oxygen electrode has been fabricated using semiconductor techniques. The oxygen electrode consists of: (a) anisotropically etched U- or V-grooves on a (100) silicon substrate as the electrolyte container; (b) a calcium alginate gell containing a 0.1 M KCl electrolyte; and (c) a directly formed gas-permeable membrane. A two-electrode configuration is used with a gold cathode and a gold anode. A novel fabrication process has been developed to allow miniaturization and mass production. Several important factors which influence the oxygen electrode characteristics have been examined. A 90% response time of 10 s is attained. A linear relationship is observed for a wide range of oxygen concentrations at 27°C. 34% of the oxygen electrodes work normally after sterlization in an autoclave. The oxygen electrode can be operated continuously for more than 40 h.

Disposable oxygen electrodes fabricated by semiconductor techniques and their application to biosensors

Abstract We fabricated a miniature Clark-type oxygen electrode using semiconductor techniques. The oxygen electrode features V-grooves to contain a 0.1 M KCl electrolyte impregnated in a gel, and a directly formed gas-permeable membrane over the gel. A fast response and a good linearity from zero oxygen concentration to saturation was obtained using the Ag/AgCl anode. The oxygen electrode was used in a disposable miniature CO 2 sensor. Also, an l -lysine sensor was developed that functions by immobilizing l -lysine decarboxylase on the sensitized area of the CO 2 sensor.

Effect of anode materials on the characteristics of the miniature clark-type oxygen electrode

Abstract A miniature Clark-type oxygen electrode was fabricated using semiconductor techniques. A two-electrode configuration was used and the effect of different anode materials on the characteristics of the oxygen electrode was examined. The cathode and anode were formed in anisotropically etched grooves and calcium alginate gel containing 0.1 M KCl electrolyte filled the grooves. A gas-permeable membrane was directly formed over the gel. By using an Ag/AgCl anode instead of a gold electrode, the response time was shortened, the residual current was decreased and the linearity of the calibration graph was improved. Good linear calibration graphs were obtained by using the Ag/AgCl anode. The Ag/AgCl anode oxygen electrode produced a stable current for 5 h at −0.8 V and for 22 h at −0.6 V.

Integrated 8×8 Electro-optic High-speed Switch for Optical Burst Transport Networks

We developed 8 times 8 beam-deflecting optical switch with a switching speed within one microsecond utilizing electro-optic effect of PLZT. A newly-developed radial optical path design and putting-in packaging structure with a monolithic PLC platform were applied.

Angle Selective Enhancement of Beam Deflection in High-Speed Electrooptic Switches

Fast electrooptic (EO) deflector switches (DSs) have high potential for applications in optical burst transport networks. EO properties of active materials used in the DSs can impose some limitations on their beam deflection efficiencies. Using a test setup with planar silica waveguide microlens arrays, thin-film ferroelec- tric oxide beam deflectors, and glass volume Bragg gratings, we demonstrate that the beam deflection angle can be increased by more than a factor of 5 for the same switching voltages. The tech- nology enables significant performance improvement of the fast EO DSs.

Micromachined glass electrode

Abstract We have used micromachining techniques to batch fabricate a miniature glass electrode on a wafer. The glass electrode has two substrates: a glass substrate with an Ag/AgCl reference electrode and a silicon substrate that serves as a container for the electrolyte solution. The silicon container is made by anisotropic etching. The sensitive area is formed over a through-hole in the silicon substrate to which a glass membrane is fusion bonded. The pH-sensitive glass membrane consists of sodium-calcium-silicate glass and 7740 glass. The electrode and container substrates are bonded by field-assisted bonding. The 90% response time is less than 5 s and we obtain a clear response curve. The average sensitivity is from −20 to −30 mV/pH.

4/spl times/4 high-speed switching subsystem with VOA (< 10 /spl mu/s) using PLZT beam-deflector for optical burst switching

We developed a 4times4 high-speed optical switch subsystem with variable optical attenuation (VOA). This switch subsystem allows high-speed level adjustment as well as high-speed switching by using the electro-optic (EO) effect of PLZT. We demonstrate 5.5-mus switching with VOA to obtain the desired output power for optical burst switching (OBS)

Electro-optic effect of lanthanum-modified lead zirconate titanate and application to optical device

We measured the optical polarization dependence of the EO effect in epitaxial PLZT films. Mainly, polar nano-region switching causes optical polarization dependence of the EO effect. We fabricated a PLZT beam deflector and assembled an optical switch with 8times8 channels and less than 1-mus switching speed.