Microfluidic connectors by ultrasonic welding

Abstract

We attempted ultrasonic welding as a technique for the bonding of connectors to microfluidic devices. Different schemes of the method were explored based on different designs of the connectors to achieve a strong, minimal dead-volume connection. Results showed that without the use of inserts, there would be unwanted flow of melt material into the conduit of the connector causing blockage. With the small scale of welding, the use of inserts and proper fixture designs were necessary to block or direct melt flow during the process. The process times were well within 1 s. Two connectors were also simultaneously welded on a microfluidic device to demonstrate the possibility of further increase in productivity in the technique. The device was able to withstand a minimum of 6 bars (gauge) pressure. Where dead-volume is not a concern, it was possible to create connection without the use of an insert by employing different connector geometry and changing the scheme of the welding. It was found out that the width of the welding zone is limited by the width of the sleeve (application of ultrasonic energy to the connector). Hence, the welding zone would proceed no further towards the conduit and causing blockage.