Experimental Study Of Ultrasonic Treatment To The Modification Of Superpolymer PDMS

Since the Miniaturized Total Analysis System was put forward from the last century, it has been developed as a significant component of the chemical analysis. Based on the Miniaturized Total Analysis System, microfluidic chip design and fabrication is an important branch of micro-electromechanical technology (MEMS). Compared with the traditional silicon chips, polymer ones have the advantages of easily fabrication, stable properties and low cost, and so on. Consequently, the study on fabrication and application of polymer chips has become a crucial development direction of the microfluidic chip.PDMS (polydimethylsiloxane) is a highly attractive substrate material for polymer microfluidic chips because of its low cost, good physical and chemical properties, and especially in good adhesion with silicon properties. However PDMS is material with low surface energy and hydrophobic prosperities, it is hardly to form a steady current on its surface. Thus the fluid driving and flow behavior in the micro-channel of the PDMS chips was seriously affected. Therefore it is of great importance to study the surface modification method of the PDMS.Ultrasonic technology is widely used in machining and material processing fields because of its easy operation, significant effect and low cost properties. In recent years, ultrasonic technology was applied to the polymer materials. In this paper, the ultrasonic technology was used to the surface modification of PDMS chips. This method can improve the hydrophility of the chip and the mechanism of this method was discussed.In order to compare the results at different ultrasonic surface modification time, the PDMS chips were divided into two groups. The contact angles were used to characterize the hydrophility of the chip. The results show that the ultrasonic surface modification method can significantly improve the wettability on the surface of the PDMS chip. After ultrasonic treatment for30min, the contact angles were decreased by2and4°respectively in group1and2on average. In some part of the chip, the surface contact angles can decreased by12°A systematic error analysis was done in this paper to avoid the errors from experiment equipment and operation processes. By the floating analysis of experimental data, the ranges of system error and the variation of contact angle dealing with ultrasound were compared. The result indicated that the variation of contact angle far outweighs the measurement floating error of contact angle from the system, so the inconspicuous change of the contact angles and the systemic error which might affect the result of experiment was eliminated.In this paper, the results of experiments were in coincidence with the mechanism analysis of ultrasonic surface modification. The results show that ultrasonic treatment can significantly improve the PDMS’ surface wettability. This paper provides a promising new method to the surface modification of PDMS material. In the experimental conditions of this paper, the biggest decrease of the contact angle on the surface of the PDMS was12°after ultrasonic treatment method.