基于局部溶解性激活的聚合物微流控芯片超声波键合

利用低于临界振幅下的超声波作用在聚合物上仅产生表面热的特点,结合PMMA在异丙醇(IPA)中的温变溶解特性,提出了一种基于局部溶解性激活的超声波聚合物微流控芯片键合方法.理论分析表明当超声振幅小于临界振幅时,只有器件接触表面产生局部表面热,而且在70℃附近IPA对PMMA的溶解性才具有良好的激活作用.在试验研究中,利用精密加工法和热压法制作了带面接触式导能筋结构和80μm×80μm微通道的PMMA微流控芯片基片.在超声振幅为13μm、键合时间8 s、键合压力300 N的条件下进行了键合试验.结果表明,芯片拉伸强度达2.25 MPa,微通道的承压能力超过800 kPa,键合后导能筋无熔融,微沟道变形率小于2%,键合时间仅为8s.该方法的键合强度和键合效率明显高于传统的键合方法,而微结构的变形率却较小,故可作为一种具有产业化前景的聚合物MEMS器件快速封接方法.

A Local Solubility Activation for Ultrasonic Bonding of Polymer Microfluidic Chips

Based on localized facial heating of low amplitude ultrasonic bonding on polymer and temperature-dependent solubility of polymethyl methacrylate（PMMA） in isopropanol（IPA）,a local solubility activated ultrasonic bonding method for rapid and robust bonding of PMMA microfluidic chip was presented in this paper.Theoretical analysis indicates that heat is generated only at the interface when ultrasonic amplitude is below critical amplitude,and the solubility of PMMA in IPA can be well activated at about 70 ℃.PMMA substrates of microfluidic chip with an area-contact style energy director and the micro-channels of 80 μm×80 μm were fabricated by precision machining method and hot embossing method,respectively.The substrates were successfully bonded under the condition of ultraosonic amplitude 13 μm,bonding time 8 s and bonding force 300 N.The tensile-strength of bonded chips was 2.25 MPa,the microchannels withstood internal pressure of 800 kPa,the dimension loss of microchannel was less than 2% and the bonding time was 8 s without melting of energy director after bonding.The bonding strength and efficiency of this method are much higher than those of traditional bonding method,while its dimension loss is smaller.So the proposed method is potentially the state-of-the-art mass-production process for sealing polymer microfluidic chips.