- 著者
- Yokomaku Hiroomi Satoh Wataru Fukuda Junji Suzuki Hiroaki
- 出版者
- American Institute of Physics
- 雑誌
- Journal of applied physics (ISSN:00218979)
- 巻号頁・発行日
- vol.104, no.6, pp.064910, 2008-09
- 被引用文献数
- 13 6
To improve the performance of electrowetting-based microfluidic devices, we used micropillar structures to enhance the changes in the wettability of gold electrodes. The changes in the contact angle of a sessile drop were influenced by the diameter of the micropillars and interpillar distances. For a potential change between 0 V and −1.0 V, the change of the contact angle of the KCl sessile drop was 41° on a smooth electrode, but 88° on an electrode with micropillars with a 10 µm diameter. Furthermore, the existence of the micropillars accelerated the change of the contact angle. The gold electrodes with the micropillars were used to generate the capillary force to mobilize a liquid column in a microflow channel. Compared to a device with a smooth electrode, this device showed a fourfold increase in the flow velocity at −0.9 V. The electrodes were also used as a valve. The ability to stop an intruding solution and the switching speed was improved with the micropillar structure.
- 著者
- Morimoto Katsuya Yamaguchi Shigeki Fukuda Junji Suzuki Hiroaki
- 出版者
- American Institute of Physics
- 雑誌
- Journal of applied physics (ISSN:00218979)
- 巻号頁・発行日
- vol.105, no.10, pp.102013, 2009-05
- 被引用文献数
- 2 3
The possibility to develop a microanalysis system for the acquisition of gastrointestinal information is presented here. The system consists of four assay sites for trypsin, pepsin, and other biochemical compounds. The major components in each assay site were a pH-responsive valve, a pH-stat used to maintain the pH of the solution to be analyzed and used for electrochemical pH-titration, and a freeze-dried enzyme substrate stored in the pH-stat. The operation of the valve is based on electrowetting, and the valve is made pH-responsive by means of a nonstandard three-electrode system. The sample solution was automatically injected into the compartment and rapidly dissolved into the substrate layer. The automatic pH-stat, based on another nonstandard use of the electrochemical three-electrode system, maintained the solution pH and, at the same time, conducted pH-titration. The determination of the activity of the proteases was conducted at their optimum pHs. The output current showed a clear dependence on the activity of the enzymes. Integrating the functions provides significant advantages for the use of this system as an isolated telemetric microsystem that may operate with wireless signal transmission using a small power supply.
- 著者
- Siribunbandal Papaorn Yamaguchi Shigeki Kojima Kenichi Fukuda Junji Suzuki Hiroaki
- 出版者
- American Institute of Physics
- 雑誌
- Applied physics letters (ISSN:00036951)
- 巻号頁・発行日
- vol.95, no.20, pp.204105, 2009-11
- 被引用文献数
- 10 9
Autonomous control of the transport of solutions in microfabricated flow channels using electrowetting-based valves and integrated electrochemical cells is proposed. An electrowetting-based valve formed with a gold electrode was opened when an electrolyte solution reached a zinc electrode in a controlling flow channel and a potential was applied to the gold electrode, causing the transport of the solution in the flow channel. Independent composite electrodes consisting of gold and zinc could function in the same manner without requiring additional electrodes. Controlled autonomous transport of solutions in a network of flow channels could also be carried out using the integrated valves.