A new approach to realize silicon based microfluidic systems has been integrating mutli-level fluidic "circuit boards" with versatile geometries. This work was performed by Bonnie Gray at NovaSensor in Fremont, CA while under a student co-op agreement. Presented below are several application of this hybrid technology.
Publication:
B.L. Gray, D. Jaeggi, N.J. Mourlas, B.P. van Drieënhuizen, K.R. Williams, N.I.
Maluf, and G.T.A Kovacs, "Novel Interconnection Technologies for Integrated
Microfluidic Systems", Sensors and Actuators A, V77 N1, November 1999, pp. 57 - 65.
Photographs and simulations of a multi-level laminating mixer structure fabricated by DRIE and wafer bonding. Mixing occurs by successive separation and reuniting of fluid streams to increase the contact area between the two fluids, resulting in faster mixing by diffusion. Operation is shown for fluid flowing at 60 µl/min using two water streams dyed with different colors. (Simulation results provided by D. Jaeggi.)
Accurate-fitting fluidic couplers between on-chip channels and off-chip fluidic devices are a challenge to the fabrication of microfluidic instrumentation. On the left is a cleaved cross section SEM photograph of one interconnect design. The interconnects are etched by DRIE in silicon. The fluidic channel is the center hole which penetrates completely through the wafer. The outside circle serves as a support and guide for an inserted capillary tube as shown in right SEM photograph.
Photograph of a fluidic circuit board demonstration system used to measure pressure drop along a channel. The five pressure sensors are mounted 4mm apart over 100-µm diameter access holes to the buried 100-µm square channel. Fluidic connections to capillary tubing are provided by two sleeve-type couplers as shown previously.
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