Study on ultrasonic fusion bonding for polymer microfluidic chips

摘要

Ultrasonic fusion bonding is a potential method for mass-production of polymer microfluidic chips owning to its advantages like short cycle time,high bonding strength, foreign substances free and so on. However, the micro structures in the chips are easily damaged or even destroyed due to poor controllability and uniformity of the melted energy directors. In this paper, a novel micro joint including energy directors and flow blocks is presented. During ultrasonic bonding, the flow profile of the melted energy directors can be controlled by the dimensions of the flow blocks. Consequently, micro structures on the chips are scarcely affected by the melted polymer. Auxiliary energy-equilibrating structures are also designed to prevent uneven melt of energy directors. Polymethyl methacrylate (PMMA) microfluidic chips with the new joints were fabricated and ultrasonic bonding experiments were conducted. Micro channels with characteristic dimension of tens of microns were successfully sealed without any deformation. And the bonding time was only 0.3 s, which is much shorter than other bonding methods. Results indicate this is a fast, high-strength and deformation free bonding method for polymer microfluidic chips.