| Summary: | 碩士 === 國立中正大學 === 光機電整合工程所 === 97 === This study focuses on fabrication of microstructure inside the photosensitive glass using a femtosecond laser directing writing method. The photosensitive glass is first processing by the laser to selectively modify its material property under the laser path. After that, following heat treatment and acid etching processes are used to fabricate the microstructure. A tapered U shape microfluidic channel, inside a photosensitive glass, with the smallest width about 5 μm in the center of a microfluidic has been demonstrated. We also found that larger laser power or lower scanning speed produced a deeper and wider microstructure. Therefore, the high laser power and low scanning speed conditions are used to fabricate the inlet and outlet parts of the tapered U shape microfluidic channel. On the other hand, smaller channel with narrow width and short depth, that is suitable for the center part of the tapered U shape microfluidic channel, was fabricated using the lower laser power or higher scan speed conditions.
We also found that the etching time is an important parameter of the microfabrication process. At the condition of a long etching time (about 50 min), the fabricated microstructures are almost the same and independent to the laser power and scanning speed. We guess that this is because the photosensitive glass is over etched so that the laser-written pattern is corrupted by the over-etching. Through the experimental data, we calculated that the etching rate of crystallized area inside glass is about 5 μm/min. Thus, microstructures with micrometer resolution can only be obtained by shortening the etching time less than several minutes. Under the proper selected process parameters (laser power, scanning speed, and etching time), we successfully fabricated 3D tapered U shape microfluidic channel inside photosensitive glass. We believe this novel fabrication process has a promised potential application in the medical device fabrication.
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