Hermetic encapsulation of negative-pressure-driven PDMS microfluidic devices using paraffin wax and glass

This paper presents a new hermetic encapsulation method for negative-pressure-driven polydimethylsiloxane (PDMS) microfluidic devices. The hermetic materials used in this encapsulation are mainly paraffin wax and glass which are not active, non-hazardous, and typically used as sealing materials for medicine and food. Compared with negative-pressure-driven devices only wrapped in air-tight plastic packages, one advantage of the new encapsulation method is that only inlet is exposed to air when the encapsulated device is unpackaged, as a result of that microfluidic devices encapsulated with the new method can achieve a higher driving pressure, a slower decline in pumping flow rate, and maintain much longer working times. In order to demonstrate the applications of these encapsulated devices, micropumps and integrated chips were designed, fabricated, and tested in this research. The back pressure, vertical flow rate, the efficiency, the channel filling time and the reservoir filling time were tested in this study. The proposed encapsulation technique can offer advantages in expanding the applications of negative-pressure-driven microfluidic devices.