development of a modular peristaltic microfluidic pump and valve system 2/13/2007 bme 273 group 20:...
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Development of a Modular Peristaltic
Microfluidic Pump and Valve System
2/13/2007
BME 273 Group 20:
Adam Dyess, Jake Hughey, Michael Moustoukas, Matt Pfister
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Microfluidics
• Minimal reagent consumption
• Increased speed of reactions
• Study of biological phenomena at the single cell level
3
Current Pumps at VIIBRE
• Harvard Pico Plus syringe pumps
• $2,000 / pump
• Limiting complexity of microfluidic devices
4
Ideal Pumping System
• Able to switch flow rates from a minimum of 50 nl/min to a maximum of 300 nl/min with an accuracy of 10 nl/min
• Able to rotate between 4 different solutions within milliseconds and no leakage
• Able to have even asynchronous flow
• Minimal cost with pumps and valves in the device
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Diagram of the System
Fluid Flow
Pneumatic Valves
Peristaltic Pump
Christmas Tree Nanophysiometer
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Pneumatic Valves
• Two-layer PDMS device– Flow layer– Control layer
• Thin PDMS membrane deflects into the flow channel when the control channel is pressurized
Unger et al. 2000
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• 4 pneumatic valves in series
• Control pressure 20-25 psi• Flow channel dimensions
– 100 um wide, 10 um tall (round) or 5 um tall (rectangular)
• Control channel– Valve area (300 um by 300
um)
• Initial estimates of flow rates at 5 nl/min
Initial Design of Peristaltic Pump
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Polyphase Pump
• In tribute to Nikola Tesla
• Increase flow rate
• Reduce non-uniformities
• Switched from nitrogen tank to air compressor – provides vacuum in the off state
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Flow Rates for Flow Layer Below
Control
Flow
0
50
100
150
200
250
300
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35
1 / Pump Period
Q (
nl/
min
)
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Results with Flow Channel Above
Control
Flow-50
0
50
100
150
200
250
300
0 0.2 0.4 0.6 0.8 1 1.2
1/Pump Period
Q (
nl/
min
)
a sticky
b nonstick
0
50
100
150
200
250
300
350
400
450
0 0.2 0.4 0.6 0.8 1 1.2
1/Pump Period
Q (
nl/
min
)
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Current Status
• Multiple inputs• Valves to selectively
block individual lanes• Flow rate tester• Calls for controller box
with at least 9 inputs• Requires extension of
LabVIEW program
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Current Work
• Measure flow rate vs. outlet pressure head• Increase cross-sectional area of flow channel• Characterize flow oscillations
– Pulse-chase with bolus of fluorescent solution– Head to head vs. syringe pump
Groisman & Quake 2004
t = 0
t = d / v
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LabVIEW Interface
• Design a user-friendly interface that allows for input of pump sequences - possibly using Excel
• Sequence includes which valves are on/off, frequency, speed, timing and repetition
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Interface Setbacks
• Pump frequency inaccuracy
• Windows must manage other programs which take up memory and time
• Results in pump speed inaccuracy
• Currently unable to correlate pump speed with input speed
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Future Work
• Investigate influence of hydrostatic forces and downstream resistance
• Long-term testing of mechanical stability of pumps
• Increase aspect ratio of flow channels
• Incorporate gradient device or T cell device on chip with pump
• Microfluidic vias if necessary
Kartalov et al. 2006
Flow