Polymer-based micromachining for microfluidic devices

A method for fabricating microchannels, comprising the steps:

• a) providing a silicon substrate, said silicon substrate having tipper and lower surfaces;
• b) depositing a first polymer layer with a defined thickness of 0.5 to 100 .mu.m on said upper surface of said silicon substrate, said first polymer layer having i) a lower surface contacting said upper surface of said silicon substrate and ii) an upper surface;
• c) photolithographically defining said first polymer;
• d) depositing a second polymer layer on said upper surface of said first layer, said second polymer layer having i) a lower surface contacting said upper surface of said first layer and ii) an upper surface;
• e) exposing said first polymer, and
• f) sacrificially etching said first polymer layer under conditions such that said second polymer layer comprises walls of a microchannel.

A method for fabricating microchannels, comprising the steps:

• a) providing a silicon wafer, said silicon wafer having upper and lower surfaces;
• b) depositing a first layer of a first polymer on said upper surface of said silicon wafer, said first polymer layer having i) a lower surface contacting said upper surface of said silicon wafer and ii) an upper surface;
• c) depositing a second polymer layer with a defined thickness of 0.5 to 100 .mu.m on said upper surface of said first layer, said second polymer layer having i) a lower surface contacting said upper surface of said first layer and ii) an upper surface;
• d) photolithographically defining said second polymer;
• e) depositing a second layer of said first polymer on said upper surface of said second polymer layer, said second layer of said first polymer having i) a lower surface contacting said upper surface of said second polymer layer and ii) an upper surface;
• f) exposing said second polymer,
• g) sacrificially etching said second polymer layer under conditions such that said first and second layers of said first polymer comprise walls of a microchannel, said microchannel having a height defined by said thickness of said second polymer layer;
• and
• h) etching one or more openings in said walls of said microchannel.