Weak solvent based chip lamination and characterization of on-chip valve and pump.

Using polystyrene as a fabrication material and pure acetonitrile as a bonding solvent, we have developed an innovative and inexpensive weak-solvent-based chip lamination process to produce highly functional, completely plastic, microfluidic chips with a 3-layer structure. This simple, scalable and rapid method allows active components, such as multiple valves and pumps, to be constructed on chip with a thin, deflectable film as the middle layer sandwiched between two polystyrene layers. Our irreversible bonding method achieves uniform lamination under mild conditions (35-45 degrees C and 10-50 KPa) without damage to the underlying micro-features. The on-chip valve and pump structures have been systematically characterized and the pumping rate has been compared against theoretical rates predicted by mathematical modeling studies. A wide range of pumping rates (0.33-10 microL/s) can be achieved, with the integral pumps maintaining a constant pumping rate and depending on pumping frequency and pump diaphragm size. Valve leakage of less than 0.02 microL/min is noted under pressures of 41 kPa. Utilizing various configurations of on-chip valves and pumps, the fully automated flow control of an integrated chip for sample lysis, nucleic acid purification and PCR is demonstrated. The present technology and chip have been heavily evaluated internally and externally for rapid biomedical diagnosis of HPV, HIV, etc., and they are currently in the process of commercialization.