MICROCHANNEL DESIGN ISSUESPRELIMINARY OUTLINEASSUMPTIONS/ CONTROL LEVELGENERAL FUNCTIONS/CONSTRAINTSGENERAL FUNCTIONS/CONSTRAINTSPOTENTIAL PROBLEMSMajor Device Fabrication AlternativesPredominate Bio-Micro Fluidics MaterialsMask Design for MoldsSlide 10Mask DesignMask DimensionsMICROCHANNEL DESIGN ISSUESMICROCHANNEL DESIGN ISSUESSusan BeattyAnne SamuelKunal ThakerPRELIMINARY OUTLINEPRELIMINARY OUTLINEAssumptionsControl Level of DesignGeneral Functions/ ConstraintsProblemsDevice FabricationMaterialsASSUMPTIONS/ CONTROL LEVELASSUMPTIONS/ CONTROL LEVELAssume externally pumped fluid flow–No need to design on-chip pumping Neglect the bio-chemistry at the test sites–Only consider how the fluid is to be transportedMust incorporate multi-level microfluidic channelsControl Level–Passive Microfluidics (Simple channels)–Active Microfluidics (Channels + Active control devices to manipulate fluid flow through numerous possible paths)GENERAL FUNCTIONS/CONSTRAINTSGENERAL FUNCTIONS/CONSTRAINTSA problem and/or functions of a design must be established prior to the consideration of a possible final design–Two possible problems have been defined which incorporate the required assumptionsControllably route each of three input lines to any one of eight different test sites (located on two levels of microchanneling) –Requires multi-level micro fluidics–Requires controllable microfluidics (must be able to control which Input line is fed to which of the eight test sites)GENERAL FUNCTIONS/CONSTRAINTSGENERAL FUNCTIONS/CONSTRAINTSRoute each of threeInputs(R,B,Y) to output each to two outputs original color will mix with one other color to create secondary colorsPOTENTIAL PROBLEMSPOTENTIAL PROBLEMSJunction–On/ off valve–1 or 2 devicesActuation–Electric–Pressure–Pressure and ElectricGeometry of the junctionMajor Device Fabrication AlternativesMajor Device Fabrication AlternativesSurface Micromachining–Standard deposition and etching techniques to remove only a small fraction of the wafer volume–Potential for use of sacrificial layers in sequential SU8 depositionBulk Micromachining–Removing bulk section of a wafer–Typically followed by wafer bonding for micro fluidics applicationsMold–Use of a mold, on which multiple polymer layers can be cured and sequentially layeredPredominate Bio-Micro Fluidics MaterialsPredominate Bio-Micro Fluidics MaterialsPDMS-PolydimethylsiloxanePMMA-PolymethylmethacrylateSU8 Pyrex GlassSiliconMask Design for MoldsMask Design for MoldsSpin SU8(negative resist) on Si wafersExpose using mask (channel mask and interconnect mask)Develop both moldsMask Design for MoldsMask Design for MoldsSpin SU8(negative resist) on Si wafersExpose using mask (channel mask and interconnect mask)Develop both moldsBottom layerMiddle layertop layerI/OI/OMask DesignMask DesignFrom molds spin on PDMS less than the vertical dimensionFrom channel mold make two layersFrom interconnect mold make one layerStack three layers in channel, interconnect, channel (90o rotation from first channel layer) orderMask DimensionsMask DimensionsFor initial preliminary fabrication larger dimensions are betterApproximate channel and interconnect width 150 mChannel length 45mmReservoirs 300m diameter (total length channel and reservoir 45.6mmDistance between channels 300mMold feature height
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