Low azeotropic solvent for bonding of PMMA microfluidic devices

A new method for sealing PMMA-based microfluidic devices using low azeotropic solvent is developed. The bonding process can be achieved in 7 min at room temperature and can successfully seal microchannels as small as 40 mm in width without clogging. The results show that the bonding strength and the increase in surface roughness following the bonding process are 3.8 ± 0.31 MPa (n = 8) and 10 nm, respectively. The bonding strength is 17-fold greater than that achieved using conventional thermal bonding techniques. Since the proposed method does not involve a heating process, it is capable of sealing microfluidic channels as wide as 3 mm without causing the channel to collapse. In order to meet the requirement of mass production process, three conventional used microdevices are adopted to confirm the feasibility of the proposed bonding method. The bonding performance is confirmed by applying the proposed method to the fabrication of three bioanalytical devices, namely a zigzag passive micromixer, a micro-CE chip and an ESI-MS chip. The results confirm that the microfluidic devices sealed using the proposed method can operate successfully under a high pressure of 26 bar and are suitable for use in high-resolution bioanalytical detection applications. The method proposed this study is potentially the state-of-the-art mass-production process for sealing PMMA microfluidic chips.