A Study of Optofluidic Devices: Microprism and Droplet Optical Modulator

• Main Authors: Tsung-Yu Lin, 林琮崳
• Other Authors: Ruey-Jen Yang
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/40176101426432606984

碩士 === 國立成功大學 === 工程科學系碩博士班 === 97 === In this research, two optofluidic devices were designed, fabricated and tested: (1) simple fluids refractive index detector and (2) droplet optical modulator. These micro-devices were fabricated using the soft lithography technique. For fluids refractive index detector, two different designs are proposed: microprism type and refraction channel type detector. The microprism type chip consists of the liquid optical waveguide channel and one triangular chamber. The tested fluid (e.g. DI water, CaCl2 aqueous solution, oil etc.) was injected into the triangular chamber. The refraction channel type chip consists of one turning channel. This channel can be regarded as a liquid-core/solid-cladding optical waveguide. The tested fluid was injected as the core layer of the waveguide, and the cladding layer was the chip substrate (PDMS). The refractive index of fluids was calculated using the simple geometrical optics principle. The experimental results showed that the refraction channel type detector performs a better measurement than microprism type detector. However, the limitation of the refraction channel type detector is that the fluids refractive index must be larger than the chip substrate refractive index to satisfy the total internal reflection condition inside the waveguide. The present data showed that the refractive index of fluids was measured accurately by our proposed two novel fluids refractive index detectors. The advantages of the two devices include simple fabrication, low sample consumption and low cost. The droplet optical modulator comprises one liquid-core/solid-cladding optical waveguide and one droplet/bubble generator (i.e. flow-focusing device). The oil was injected as the carrier phase and the core layer of the waveguide. Air, DI water and CaCl2 aqueous solution were adopted as the dispersed phase, respectively. The different droplet/bubble sizes were created inside the waveguide to destruct the total internal reflection phenomenon and results in optical attenuation. The experimental results showed that the degree of optical attenuation increases as the refractive index of droplet/bubble is decreased. In addition, the optical attenuation increases with increasing the droplet/bubble size and reaches a limiting value.