Low-deformation precision thermal bonding of nanostructured microfluidic chips

Polymer bonding is widely employed in thermal welding, ultrasonic welding, laser welding, and surface-activated bonding. To adapt bonding properties to the smaller microstructure and complexity of a microfluidic chip, the bonding process should produce low polymer structure deformation and strong bonding strength. To fabricate a microfluidic chip without an adhesive layer, a new precision polymer bonding process that employs a nanostructure and two different layers of the same polymer material with different glass transition temperatures (Tg ) is devised. Low-temperature bonding (less than 20 °C) was achieved. A deformation ratio of 1.1% was obtained, which is 10 times smaller than that for the typical thermal-bonding process. Thus, a precision bonding technique for a low-deformation microstructured chip was successfully developed.