1998 Fiscal Year Final Research Report Summary
High Sensitive Detection of Biochemical Substances Using by Thin-film Optical Waveguide Sensor
| Project/Area Number |
09650486
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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 |
計測・制御工学
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| Research Institution | Keio University |
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Principal Investigator |
MINAMITANI Haruyuki Keio University, Faculty of Science and Technology, Professor, 理工学部, 教授 (70051779)
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| Co-Investigator(Kenkyū-buntansha) |
SASAKI Keisuke Chitose Institute of Science and Technology, Professor, 教授 (00051425)
NIHEI Eisuke Keio University, Faculty of Science and Technology, Assistant Professor, 理工学部, 講師 (10228257)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Biosensor / Ion Senser / Thin-film Optical Waveguide / Evanescent Light / Glucose Sensor / Visible Laser / Ionophore |
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| Research Abstract |
In order to measure concentration of biochemical substances and ion solutions with high sensitivity and wide range band, thin-film optical waveguide sensor was developed under the basis of theoretical consideration of optimal waveguide construction. Three layers slab type of optical waveguide was constructed by substrate (clad) layer, waveguide (core) layer and sample (clad) layer. Sensitivity of evanescent field absorption, complex propagation constant of the waveguiding and interaction ratio of the waveguide sensor to aqueous light-absorbing species, which are measure of device sensitivity, were theoretically and experimentally investigated. Pyrex glass plate (refractive index n=l.47) for the substrate layer and rf-sputtered Corning 7059 glass (n=1.58) for the waveguide layer were used respectively. Top clad layer was composecd by air layer and sample layer on which very small quantity of biochemical aqueous solution was droped. Principle of the optical sensing was based on the evane
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scent field absorption of biochemical molecules and ions at the specific light wavelength. Oxy- and deoxyhemoglobin concentration and glucose concentration with chemo-reactive enzyme were measured by using the evanescent field absorption method. Another type of waveguide having composite polymer (PVCPVA) core layer (n=l.51) was also developed by means of spin-coating method. In the composite polymer, ion selective ionophore and specific dye were doped, of which sensing mechanism was dependent on changing of light absorption of the doped medium when the objective ion was specifically combined with the ionophore. Concentration of Na, K or Ca ion was selectively detected by changing the respective ionophores. This type of sensor was functioned not by evanescent field absorption but by bulk absorption. One of limitations of conventional ATR spectrophotometry was poor sensitivity for weakly light absorbing samples. This arises from that the effective sample thickness and length are in the order of penetration depth and length of the evanescent wave. The proposed optical waveguide sensor gave enough high interaction length between the evanescent field and sample meidum and therefore it was available to high sensitivity and wide range of concentration measurement. In this study, a new method of short time measurement for ion concentration calculation was also proposed by using exponential response curve fitting. Less
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