Mask Design for Molds

1. Mask Design for Molds

2. Mask Design for Molds • Spin SU8(negative resist) on Si wafers • Expose using mask (channel mask and interconnect mask) • Develop both molds

3. Mask Design for Molds • From molds: spin on PDMS less than the vertical dimension • From channel mold: make two layers • From interconnect mold: make one layer • Stack three layers in channel, interconnect, channel (90o rotation from first channel layer) order I/O Bottom layer I/O Middle layer Top layer

4. Mask Dimensions • For initial preliminary fabrication larger dimensions are better • Approximate channel and interconnect width 150 mm • Channel length 45mm • Reservoirs 300mm diameter (total length channel and reservoir 45.6mm • Distance between channels 300mm • Mold feature height 300mm

6. Modified Mask Design for Molds • Spin SU8(negative resist) on Si wafers • Expose using mask (channel mask, interconnect mask, and top mask) • Develop all three molds

7. Modified Mask Design for Molds • From molds: spin on PDMS less than the vertical dimension for all four layers • From channel mold: make two layers • From interconnect mold: make one layer • From top mold: make one layer • Stack all four layers in channel, interconnect, channel (90o rotation from first channel layer), and top order

8. Modified Mask Dimensions • Coordinate of the reservoirs (mm): • (20.0,20.9), (5.6,12.8), (12.8,5.6) in all four quadrants • Coordinates of the channel intersections (mm): • (0,0),(0,7.2),(7.2,0),(3.6,3.6) in all four quadrants • Channel Width: 150 mm • Reservoir Diameter: ?

9. Modified Mask Considerations • How many of the nine channel intersections should be used as interconnects between layers (3 or 9) • Should the first channel layer be open or closed on the bottom surface (PDMS or Pyrex bottom) • Should a top layer channel be used or should the top remain open • Should the size of the reservoir throughputs be the same size or smaller then the reservoirs