MICRO PUMPS, VALVES AND MIXERSOUTLINEMICROPUMPSGENERAL TYPES OF MICROPUMPSBUBBLE/DIFUSSER PUMPMEMBRANE PUMPSROTARY PUMPSELECTROHYDRODYNAMIC PUMPSELECTROOSMOTIC/ ELECTROPHORETIC PUMPSULTRASONIC/OPTICAL PUMPSVALVESVALVE CLASSIFICATIONNON_MOVING VALVESPASSIVE VALVESPASSIVE VALVES (con’t)ACTIVE VALVESMICROMIXERSGENERAL TYPES OF MIXERSLAMINATING MIXERSPLUME MIXERSACTIVE MIXERSKEY POINTSKEY POINTS (con’t)Slide 24MICRO PUMPS, VALVES AND MIXERSMICRO PUMPS, VALVES AND MIXERSSusan BeattyDave NiKunal ThakerOUTLINEOUTLINEMicro pumpsMicro valvesMicro mixersKeypoints (conclusion)MICROPUMPSMICROPUMPSGENERAL TYPES OF MICROPUMPSGENERAL TYPES OF MICROPUMPSBUBBLE PUMPSDIFUSSER PUMPS MEMBRANE PUMPS (most common)ROTARY PUMPSELECTROHYDRODYNAMIC PUMPSELECTROOSMOTIC/ ELECTROPHORETIC PUMPSULTRASONIC PUMPSOPTICAL PUMPSBUBBLE/DIFUSSER PUMPBUBBLE/DIFUSSER PUMPThe formation and collapse of a bubble in the liquid is used to drive the flow of the liquidAllows for a valve-less diffuser designGreatly enhances mixing of the constituent phasesFlow rate in the range of 4-5 μL/sec for 250-400Hzhttp://www.me.berkeley.edu/~lwlin/papers/2002Tsai.pdfMEMBRANE PUMPSMEMBRANE PUMPSMethod of displacing the membrane–Magnetically–Electrostatically–With a piezoelectric–Thermally (SMA and thermopneumatically)Sensitive to blockage by particulates in the fluidFlow rate in the range of 100-10000 μL/sechttp://ej.iop.org/links/60/IYwveEquvuX,ovtuKcQOMw/jm8218.pdf http://www.ajou.ac.kr/~mems/proj-1-1.htmROTARY PUMPSROTARY PUMPSVery rare and not commonly researchedExtremely complicated fabrication processHigh susceptibility to failureVery precise control of the fluid flow and directionGood for transporting high impurity liquidshttp://cmmt.gatech.edu/Mark/Publications/Allen_95_Fluid_Micropumps_Rot_Mag_Actu.pdfELECTROHYDRODYNAMIC PUMPSELECTROHYDRODYNAMIC PUMPSUses an applied electric field on the fluid to be pumped to induce charge and also to electrostatically move the induced chargesNot suitable for the delivery of most biological fluids, as a very specific fluid conductivity is requiredExtremely high voltages are required to move the fluids (~700volts)Has an equivalent magnetohydrodynamic pumpELECTROOSMOTIC/ ELECTROPHORETIC PUMPSELECTROOSMOTIC/ ELECTROPHORETIC PUMPSElectrophoretic pumping relies on the presence of ions in the fluid–The ions are manipulated through the application of an electric field and flow is inducedElectroosmotic flow relies on the presence of ions on the surfaces of the fluidic channel Example- between glass and organic fluids–An applied electric field allows for the movement of the bulk fluidFlow rate on the order of 15 μL/secNo moving partshttp://www.stanford.edu/~chenaiwa/Micropump_Jmems.pdfULTRASONIC/OPTICAL PUMPSULTRASONIC/OPTICAL PUMPSUltrasonic pumps use piezoelectric networks to actuate on a cyclical basis to produce predictable fluid motion–Most applicable to mixing, not pumpingIn optical pumps, heat is introduced to the fluid by way of optical absorption–Gradients in the fluids heat result in viscosity and surface tension gradients, which in turn lead to fluid flow by way of the thermocapillary effect–Most applicable to mixing, not pumpingVALVESVALVESVALVE CLASSIFICATIONVALVE CLASSIFICATIONNon-moving valvePassive valvesActuated valvesNON_MOVING VALVESNON_MOVING VALVESDiffuser Valve–Provides directional resistancehttp://www.cr.org/publications/MSM2001/html/T67.02.htmlPASSIVE VALVESPASSIVE VALVESCantileverDiscMembraneShoji, Journal of micromechanics and microengineering 1994PASSIVE VALVES (con’t)PASSIVE VALVES (con’t)PistonGas controlledhttp://www.ca.sandia.gov/microchem/microfluidics/valves/valves1.htmlQuake, Science 2000ACTIVE VALVESACTIVE VALVESValve types based on actuation–Electromagnetic–Piezoelectric–Pneumatic–Shape memory alloy–Thermopneumatic–ChemicalMICROMIXERSMICROMIXERSDefinition: The controlled micro-mixing of two or more fluidsGENERAL TYPES OF MIXERSGENERAL TYPES OF MIXERSLaminating MixersPlume MixersActive MixersMicrograph of Silicon-glass -- Copyright, Meinhart, Bayt 1998 http://www.engineering.ucsb.edu/~nari/mycurrentresearch.htmLAMINATING MIXERSLAMINATING MIXERSAt the microscopic scale the use of laminating mixers is try to “laminate” two or more fluids together to increase the contact area and enhance diffusion (0.5 to 12 l/min)Two fluids entering the inlet ports laminate at the first horizontal junction, producing two side-by-side fluid streams. Successive vertical separation and horizontal reuniting of fluid streams increases the number of laminates with each stage and, thus, the contact area between the two fluids.http://transducers.stanford.edu/stl/Projects/fluidic-charact.htmlPLUME MIXERSPLUME MIXERSTakes advantage of the behavior of a fluid leaving a narrow nozzle (15m)Generates a small plume which increases the contact area of two liquidsHomogeneous mixing in 1.2 secs in a 0.5 l volume at a 45 l/min flow rateACTIVE MIXERSACTIVE MIXERSThe use of external energy–Ultrasonic traveling wave pumps moving fluids in a circulating path–Bubble pumps – two large pumps used to generate push & pull forcesKEY POINTSKEY POINTSMembrane pumps are the most common type of micro pumping device currently fabricatedAn attempt is being made to phase out check valves and other mechanisms that slow down the frequency response of the pumping system.–Drive toward diffuser valvesMore flow loss, but increase in frequency.Pumps with non-moving parts are preferred due to higher reliability, etc.Bubble, electroosmotic, and electrophoretic pumps tend to be the direction in bio-micro fluidics applications.KEY POINTS (con’t)KEY POINTS (con’t)Passive valves are commonly used because they are easier to fabricate and are smaller that actuated valvesThe easier and cheaper the valve is to fabricate the more likely it will be usedChemically reactive valves are ideal for bio-microfluidics because they are easy to make, they are small and they behave as an active valveKEY POINTS (con’t)KEY POINTS (con’t)Laminating Mixers – to laminate fluids togetherPlume Mixers – plume is generated to increase contact area of two liquidsActive Mixers – uses external energy to mix
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