Facile fabrication of microfluidic systems using electron beam lithography.

We present two fast and generic methods for the fabrication of polymeric microfluidic systems using electron beam lithography: one that employs spatially varying electron-beam energy to expose to different depths a negative electron-beam resist, and another that employs a spatially varying electron-beam dose to differentially expose a bi-layer resist structure. Using these methods, we demonstrate the fabrication of various microfluidic unit structures such as microchannels of a range of geometries and also other more complex structures such as a synthetic gel and a chaotic mixer. These are made without using any separate bonding or sacrificial layer patterning and etching steps. The schemes are inherently simple and scalable, afford high resolution without compromising on speed and allow post CMOS fabrication of microfluidics. We expect them to prove very useful for the rapid prototyping of complete integrated micro/nanofluidic systems with sense and control electronics fabricated by upstream processes.