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Wideband coplanar-waveguide (CPW) bandpass filters based on the cascade of CPW lowpass and highpass periodic structures are proposed. The upper and lower stopband characteristics of proposed bandpass filter can be easily designed by separately adjusting the lowpass and highpass sections, respectively. Specifically, two wideband CPW bandpass filters with sharp roll-off at passband edges and good stopband rejection are demonstrated.

A novel surface plasmon resonance (SPR) imaging system based on modified Mach-Zehnder phase-shifting interferometry (PSI) measures the spatial phase variation of a resonantly reflected light in biomolecular interaction. In this technique, the SPR DNA microarray can diagnose the target DNA without additional labeling in real-time biomolecular interaction analysis (BIA). Owing to the feasible and swift measurements, the SPR microarray with this SPR imaging system can be extensively applied to the nonspecific adsorption of protein, the membrane-protein interaction, receptor-ligand interaction, DNA hybridization. The detection limitation of the SPR PSI imaging system is improved to about 1 pg/mm2 surface coverage of biomaterial for each individual spot over that of the conventional SPR imaging system that observe the intensity variation of a resonantly reflected light. The SPR PSI imaging system and its SPR microarray can provide the capability to analyze DNA hybridization or protein interaction in real-time, with high resolution, and at high-throughout screening rates.

The biosensors based on surface plasmon resonance (SPR) are often used as tools for directly detecting the kinetic interaction of unlabelled biological molecules at surface in real time. With the measured SPR reflection spectrum, we can detect a shift in the location and quantity of the reflection spectrum minimum and the half width at half maximum due to the change in the thickness or the refractive index of a thin dielectric film layer. The interested parameters of analyte layer or monolayer, like the molecular size and concentration, can be determined either with analytical approaches or linear data analysis approaches. Depends on the number of parameters need to be resolved, we may need either multiple spectra (two color method) or only one sensing spectrum under the assumption that the other film parameter is given for multiple parameters case. Although it is possible to estimate multiple parameters from only one sensing spectrum by linear estimation techniques, it suffers from not only the shortcoming for larger variance in the estimates from those techniques than that of multiple spectra method but also the difficulty for choosing the appropriate initial value in the estimation process. In this paper, we propose a modified analytic approach to attain suitable initial parameters that close enough to the exact value. Furthermore, we incorporated multi-experiment method into linear estimation algorithms to determine the optimal estimated parameters with smaller variability of the estimated parameters. In that manner, it would be benefit to reject the colored noise accidentally results from experiment process. The experimental data with the multi-experiment linear data analysis demonstrates that it has ability to sense slightly index change in consequence of argon gas flow through the nitrogen.

Surface plasmon resonance (SPR) imaging system is presented as a novel technique based on modified Mach-Zehnder phase-shifting interferometry (PSI) for biomolecular interaction analysis (BIA), which measures the spatial phase variation of a resonantly reflected light in biomolecular interaction. In this technique, the micro-array SPR biosensors with over a thousand probe NDA spots can be detected simultaneously. Owing to the feasible and swift measurements, the micro-array SPR biosensors can be extensively applied to the nonspecific adsorption of protein, the membrane/protein interactions, and DNA hybridization. The detection sensitivity of the SPR PSI imaging system is improved to about 1 pg/mm2 for each spot over the conventional SPR imaging systems. The SPR PSI imaging system and its SPR sensors have been successfully used to observe slightly index change in consequence of argon gas flow through the nitrogen in real time, with high sensitivity, and at high-throughout screening rates.