• Journal of Sensor Science and Technology
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• v.14 no.5
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• pp.302-307
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• 2005

Precision displacement of less than a few nm resolution was measured in real-time using fiber optic EFPI sensor. The novel method for real-time processing of analyzing EFPI output signal was developed and verified. Linearity in the mean values of interferometric light intensity among adjacent fringes was shown and verified the sinusoidal approximation algorithm that estimates past and coming fringe values. Real-time signal processing program was developed and the intensity signal of the EFPI sensor was transformed to the phase shift with this program. The resolution below $0.36{\sim}8.6$ nm in the displacement range of $0{\sim}300{\mu}m$ was obtained. The nano-positioner with a piezoelectric actuator and the EFPI sensor system was designed and tested. The positioner successfully reached to the desired destination within 1 nm accuracy.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.2
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• pp.118-126
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• 2004

Recombinant E.coli ACV 1003 (recA::lacZ) releasing ${\beta}$-galactosidase by a SOS regulon system, when exposed to DNA-damaging compounds, have been used to effectively monitor endocrine disruptors. Low enzyme activity of less than 10 units/mL, corresponding to a $\mu\textrm{g}$/L(ppb) range of an endocrine disruptor (tributyl tin, bisphenol A. etc.), can be rapidly determined, not by a conventional time-consuming and tedious enzyme assay, but by an alternative interferometric biosensor. Heavily boron-doped porous silicon for application as an interferometer, was fabricated by etching to form a Fabry-Perot fringe pattern, which caused a change in the refractive index of the medium including ${\beta}$-galactosidase. In order to enhance the immobilization of the porous silicon surface, a calyx crown derivative (ProLinker A) was applied, instead of a conventional biomolecular affinity method using biotin. This resulted in a denser linked formation. The change in the effective optical thickness versus ${\beta}$-galactosidase activity, showed a linear increase up to a concentration of 150 unit ${\beta}$-galactosidase/mL, unlike the sigmoidal increase pattern observed with the biotin.

• Journal of Integrative Natural Science
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• v.3 no.2
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• pp.78-83
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• 2010

DBR/Host dual porous silicons containing DBR and host structure were prepared and their optical properties were characterized using Ocean Optics spectrometer. In this dual porous silicon, single porous silicon layer was used as host layer for possible biomolecule and drug materials and DBR porous silicon layer was used for signal transduction due to the recognition of molecules. Optical reflection spectrum of dual porous silicon displayed only DBR reflection but Fabry-Perot fringe pattern. DBR reflection band of dual porous silicon shifted to the shorter wavelength as the etching time of host layer increased. Cross-sectional FE-SEM image of dual porous silicon displayed a thickness of about 20 micrometer for DBR porous silicon layer. Developed etching technology could be useful to prepare DBR porous silicon which exhibited specific reflection resonance at the required wavelength and to provide an label-free biosensors and drug delivery materials.