Improved performances of all-polyimide fluidic devices using thermal nanoimprinting

Flexible micropumps are important components for advanced microfluidic systems. Here, polyimide (PI) for flexible micropumps was focused on. This is because PI has many advantageous properties such as good biocompatibility, high thermal stability, and superior mechanical strength. However, the difficulty in realizing an all-PI micropump lies in fabricating microstructures on PI film surfaces. In this paper, we present improved performances of a flexible all-PI micropump fabricated using high-temperature hot embossing above 320°C that is considerably higher than its glass transition temperature of 275°C. The fabricated micropump had diffuser/nozzle valves and a chamber with 5 mm diameter, and it was functioned by vibrating a 2-μm-thick PI diaphragm with alternating air pressures outside of the diaphragm. The flow rate of deionized water in the micropump reached to 110 μl/min at 3 Hz.