|Author's Email Address
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||Mechanical and Electro-Mechanical Engineering|
|Type of Document
||Wavelength-Resolved, Objective Lens Based Surface Plasmon Resonance System for High Spatial Resolution Bio-detection Applications|
|Date of Defense
||total interal reflection objectives
surface plasmon resonance microscpe
surface plasmon resonance
||Real-time biomolecule interaction analysis (BIA) sensor chips are widely used in biomedical testing. Over the developed techniques, surface plasmon resonance shows the most promising for these applications. Optic fiber based SPR sensors exhibit the advantage of low-cost but it is difficult to integrate with microfluidic systems. The angle variation detection is promising to integrate with microfluidic system for real-time detection. However, conventional angle-variation SPR detection schemes are usually limited by the relatively big size of the incident light spot and the difficulty for real-time optical image observation. In addition, an expensive goniometer is required to obtain precise angle measurement. Therefore, it is essential to develop a system for simultaneously optical image observation and SPR detection without using the moving part. |
This work presents a TIRF objective-based surface plasmon resonance (SPR) system for simultaneously image capturing and wavelength- resolved SPR detecting for microfluidic applications. The light from a low-cost tungsten bulb passes through a designed light stop and polarizer is used as the light source for SPR detecting. The light spot is reduced to around 15 m after passing through the 60X objective lens, resulting in a higher spatial resolution for SPR detection in microfluidic channels. Moreover, the designed confocal scheme makes the system capable of simultaneously optical observation and SPR detection without scanning the wavelength or switching the optical system. Results show that the developed system is capable of detecting samples of refractive index in the range from 1.0 to 1.38 with a sensitivity of around 3417 nm/RIU. The developed system provides a simple yet high performance method for on-site detecting the SPR spectra anywhere inside a microfluidic device.
The system was constructed under a home-built microscope system. A tungsten bulb was used for the light source for SPR excitation. The light passed through a designed light-stop with a 1.0 mm hole to obtain light beam with continuous wavelength. The light beam then passed through the polarizer (TM mode) and deflect using a TIRF objective lens for SPR excitation. With this approach, the incident light beam can be further condensed into a small light spot such that the spatial resolution can be enhanced.
The system setup for simultaneously image capturing and high spatial SPR detection. The reflected light beam was collected using a multimode optic fiber and analyzed with a high performance spectrometer for SPR analysis. A low N.A. objective lens was used for simultaneously capturing the image while SPR detection. Therefore, microscopic image and SPR analysis can be achieved in a simple system without moving or scanning parts. Results show that the off-axis distance of 5.8 mm has the greater SPR performance.
This study has measured the signal of SPR upon TIR Objective successfully. Whether we changed the d off-axis distance corresponding to a different angle of incidence, or changed in the refractive index of the sample, we all find the obvious SPR wavelength of the light intensity lost. This optical architecture development will create a high spatial resolution and the utilization of high-density chip system which will integrate and reduce the cost of making the SPR measurement stage.
||Lung-Ming Fu - chair|
Jui-Hung Hsu - co-chair
Chia-Yen Lee - co-chair
Yu-Ju Hung - co-chair
Che-Hsin Lin - advisor
Indicate in-campus at 99 year and off-campus access at 99 year.|
|Date of Submission