| Project/Area Number |
15510107
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Nanomaterials/Nanobioscience
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| Research Institution | Toin University of Yokohama |
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Principal Investigator |
MIYASAKA Tsutomu Toin University of Yokohama, Graduate School of Engineering, Professor, 工学研究科, 教授 (00350687)
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| Co-Investigator(Kenkyū-buntansha) |
徳岡 由一 桐蔭横浜大学, 工学部, 講師 (30339907)
渡辺 正 東京大学, 生産技術研究所, 教授 (70092385)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2005: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2004: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2003: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Keywords | bacteriorhodopsin / halobacteria / proton pump / tin oxide electrode / optical sensing / artificial retina / photoelectrochemistry / purple membrane |
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| Research Abstract |
Natural purple membrane (PM) of halobacteria comprising two-dimensional crystals of bacteriorhodopsin (BR), the photoactive ion pump, was dispersed in pure water and immobilized on a solid electrode surface by controlling its molecular orientation and the BR-modified electrode was investigated for its potential applications to construction of optical image sensors and artificial retina. For PM immobilization, multilayer deposition by the Langmuir-Blodgett (LB) method and spin coating method were attempted. In the LB method, special means was studied in which homogeneity and orientation of PM were controlled by applying a DC electric field across the supernatant membrane (Langmuir film) at the air-water interface in combination with vibration treatment caused by ultrasonic wave irradiation. This treatment of the supernatant film has been proved to achieve a denser packing of molecules by a model experiment in which spyropiran as a photosensitive molecule was used.
The PM-coated electrode
… More
was combined with a platinum or gold counter-electrode by insertion of an aqueous electrolyte layer to form a thin photoelectric device as a model of artificial retina. Visible light illumination of the device causes a transient photocurrent which responds to the time differential calculus of a change in light intensity, similar to the electrical signal pattern generated at retina. For application to optical sensing, two improvements have been attempted in the device fabrication. One is the use of an aqueous gel to solidify the electrolyte layer. The other was the use of a conductive plastic electrode to convert the device into a flexible device, which is more suitable for medical application as the artificial retina. In the former study, use of a viscous aqueous gel comprising sodium arginate and KCl proved to give a high efficiency in photocurrent generation compared to aqueous electrolyte solution. In the latter improvement, indium tin oxide (ITO)-coated PET film was modified with a cast film of PM, in which orientation of the cast film was controlled by exposing the film-forming PM dispersion to a strong DC electric field. A BR-coated flexible plastic device as an optical sensor was fabricated and its performance was optimized by changing the film-forming conditions. UV/ozone treatment was applied to hydrophilize the ITO-PET surface, which gave better adhesion strength to the PM film.
Using these immobilization methods, various types of image sensors bearing a 2-dimensional array of pixels were assembled to study the function of the sensors as artificial retinas. A 246-pixel image sensor was fabricated using an ITO-patterned electrode bearing a cast film of PM, which demonstrated motion sensing ability of the BR-immobilized device. Effect of the external circuit attached to the sensor was also investigated in an attempt to implement additional image-processing functions. For example, simultaneous use of current amplifier and charge amplifier showed that the sensing system is endowed with sensing functions with respect to moving target and still image, simultaneously. This result was reported in international conference on MEMS, 2005. Less
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