Energy director structure and self-balancing jig for the ultrasonic bonding of microfluidic chips.

Ultrasonic bonding was widely used to seal polymer microfludic chips due to its high strength, low cost and good biocompatibility. However, in the process of ultrasonic bonding, the easy clogging of microchannels and the difficulty of controlling microchannel heights limit the use of ultrasonic bonding in mass fabrication. In this study, energy director's structure including director protrusion, bonding limited platform and bonding pool is designed and used. A self-balancing jig is designed to automatically adjust with the horn and produce an even bonding energy distribution. Ultrasonic bonding parameters including bonding pressure and bonding time are optimised. The tensile destruction test, leakage test and serum driving test are employed to measure the performance of the ultrasonic bonding chips. Results have shown that the energy director's structure and the self-balancing jig can obviously reduce the clogging of microchannels and improve the uniformity of microchannel heights. By using the optimised bonding parameters, the bonding strength has reached >2.5 Mpa, and channel leakage has not been observed under 0.7 MPa air pressure. The energy director's structure and the self-balancing jig presented here can provide an effective alternative for the mass ultrasonic bonding of microfluidic devices. [ABSTRACT FROM AUTHOR]