| Summary: | 碩士 === 國立中興大學 === 機械工程學系所 === 99 === Polydimethylsiloxance (PDMS) is the most widely used material in developing the microfluidic devices. Unfortunately, PDMS is a kind of hydrophobic material and can’t be bonded strongly to itself or glass. In order to enhance its bonding strength, O2 plasma has been studied to clean and modify the surface of PDMS to become clean and hydrophilic to improve its bonding strength.
This study is to analyze the effect of processing parameters and plasma equipment structure on the surface modification of PDMS by O2 plasma. The parameters focused in this study include the processing time, plasma power, and vacuum pressure. Two plasma sources including ICP and CCP types, along with the cassette, were also studied independently by varying the processing parameters. Following the analysis of the system effect on the surface modification, the formation of the silica-like layer after plasma modification was studied, followed by the analysis of the recovery of treated surface when storing the processed samples in the air. Finally, the bonding strength of the modified PDMS to PDMS and modified PDMS to glass were test and compared to the samples without receiving any O2 plasma treatment.
In order to quantify the change of material structure on treated surface, the water based contact angle measurements, Fourier Transform Infrared Spectroscopy (FTIR) and XPS spectroscopy were used in this study. These tests were followed by the standardized blister test for measuring the bonding strength of treated samples.
The results show that the process parameters affect the performance of the PDMS surface modification at different levels, and the interaction between parameters is clearly observed. After observing the sample location and plasma source effect, the samples at different locations show different surface treatment results. The difference between samples treated by ICP and CCP plasma source is observed clearly as well. In studying the recovery of surface condition after plasma treatment, proper selection of processing parameters can reduce the speed of recovery for treated samples. Finally, the bonding strength for treated samples is observed to increase as the contact angle for treated PDMS decreased.
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