A low-temperature parylene-to-silicon dioxide bonding technique for high-pressure microfluidics

We introduce a new low-temperature (280 °C) parylene-to-SiO2 bonding process with high device yield (>90%) for the fabrication and integration of high-pressure-rated microfluidic chips. Pull tests demonstrate a parylene-to-SiO2 bonding strength of 10 ± 3 MPa. We apply this technique for bonding Pyrex and silicon wafers having multiple metal layers to fabricate standard packaged microfluidic devices. By performing electrochemical impedance spectroscopy of electrolyte solutions in such devices, we demonstrate that electrodes remain functional after the etching, bonding and dicing steps. We also develop a high-pressure microfluidic and electrical integration technology, eliminating special fluidic interconnections and wire-bonding steps. The burst pressure of the integrated system is statistically shown to be 7.6 ± 1.3 MPa, with a maximum achieved burst pressure of 11.1 MPa, opening perspectives for high-pressure applications of these types of microfluidic devices.