micro pumps, valves and mixers susan beatty dave ni kunal thaker
TRANSCRIPT
MICRO PUMPS, VALVES AND MIXERS
MICRO PUMPS, VALVES AND MIXERS
Susan Beatty
Dave Ni
Kunal Thaker
OUTLINEOUTLINE
Micro pumps Micro valves Micro mixers Keypoints (conclusion)
MICROPUMPSMICROPUMPS
GENERAL TYPES OF MICROPUMPS
GENERAL TYPES OF MICROPUMPS
BUBBLE PUMPS DIFUSSER PUMPS MEMBRANE PUMPS (most common) ROTARY PUMPS ELECTROHYDRODYNAMIC PUMPS ELECTROOSMOTIC/ ELECTROPHORETIC
PUMPS ULTRASONIC PUMPS OPTICAL PUMPS
BUBBLE/DIFUSSER PUMPBUBBLE/DIFUSSER PUMP
The formation and collapse of a bubble in the liquid is used to drive the flow of the liquid
Allows for a valve-less diffuser design Greatly enhances mixing of the constituent
phases Flow rate in the range of 4-5 μL/sec for 250-
400Hz
http://www.me.berkeley.edu/~lwlin/papers/2002Tsai.pdf
MEMBRANE PUMPSMEMBRANE PUMPS Method of displacing the membrane
– Magnetically– Electrostatically– With a piezoelectric– Thermally (SMA and thermopneumatically)
Sensitive to blockage by particulates in the fluid Flow rate in the range of 100-10000 μL/sec
http://ej.iop.org/links/60/IYwveEquvuX,ovtuKcQOMw/jm8218.pdf http://www.ajou.ac.kr/~mems/proj-1-1.htm
ROTARY PUMPSROTARY PUMPS Very rare and not commonly researched Extremely complicated fabrication process High susceptibility to failure Very precise control of the fluid flow and direction Good for transporting high impurity liquids
http://cmmt.gatech.edu/Mark/Publications/Allen_95_Fluid_Micropumps_Rot_Mag_Actu.pdf
ELECTROHYDRODYNAMIC PUMPS
ELECTROHYDRODYNAMIC PUMPS
Uses an applied electric field on the fluid to be pumped to induce charge and also to electrostatically move the induced charges
Not suitable for the delivery of most biological fluids, as a very specific fluid conductivity is required
Extremely high voltages are required to move the fluids (~700volts)
Has an equivalent magnetohydrodynamic pump
ELECTROOSMOTIC/ ELECTROPHORETIC
PUMPS
ELECTROOSMOTIC/ ELECTROPHORETIC
PUMPS Electrophoretic pumping relies on the presence of ions in the fluid
– The ions are manipulated through the application of an electric field and flow is induced
Electroosmotic 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 fluid
Flow rate on the order of 15 μL/sec No moving parts
http://www.stanford.edu/~chenaiwa/Micropump_Jmems.pdf
ULTRASONIC/OPTICAL PUMPS
ULTRASONIC/OPTICAL PUMPS
Ultrasonic pumps use piezoelectric networks to actuate on a cyclical basis to produce predictable fluid motion– Most applicable to mixing, not pumping
In 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 pumping
VALVESVALVES
VALVE CLASSIFICATIONVALVE CLASSIFICATION
Non-moving valve Passive valves Actuated valves
NON_MOVING VALVESNON_MOVING VALVES
Diffuser Valve– Provides
directional resistance
http://www.cr.org/publications/MSM2001/html/T67.02.html
PASSIVE VALVESPASSIVE VALVES
Cantilever
Disc
Membrane
Shoji, Journal of micromechanics and microengineering 1994
PASSIVE VALVES (con’t)PASSIVE VALVES (con’t)
Piston
Gas controlledhttp://www.ca.sandia.gov/microchem/microfluidics/valves/valves1.html
Quake, Science 2000
ACTIVE VALVESACTIVE VALVES
Valve types based on actuation– Electromagnetic– Piezoelectric– Pneumatic– Shape memory alloy– Thermopneumatic– Chemical
MICROMIXERSMICROMIXERS
Definition: The controlled micro-mixing of two or more fluids
GENERAL TYPES OF MIXERS
GENERAL TYPES OF MIXERS
Laminating Mixers
Plume Mixers
Active Mixers
Micrograph of Silicon-glass -- Copyright, Meinhart, Bayt 1998
http://www.engineering.ucsb.edu/~nari/mycurrentresearch.htm
LAMINATING MIXERSLAMINATING MIXERS
At 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.html
PLUME MIXERSPLUME MIXERS
Takes advantage of the behavior of a fluid leaving a narrow nozzle (15m)
Generates a small plume which increases the contact area of two liquids
Homogeneous mixing in 1.2 secs in a 0.5 l volume at a 45 l/min flow rate
ACTIVE MIXERSACTIVE MIXERS
The use of external energy– Ultrasonic traveling wave pumps
moving fluids in a circulating path
– Bubble pumps – two large pumps used to generate push & pull forces
KEY POINTSKEY POINTS Membrane pumps are the most common type of
micro pumping device currently fabricated An 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 valves
More 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 valves
The easier and cheaper the valve is to fabricate the more likely it will be used
Chemically reactive valves are ideal for bio-microfluidics because they are easy to make, they are small and they behave as an active valve
KEY POINTS (con’t)KEY POINTS (con’t)
Laminating Mixers – to laminate fluids together
Plume Mixers – plume is generated to increase contact area of two liquids
Active Mixers – uses external energy to mix fluids