Development of a Modular Peristaltic Microfluidic Pump and

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

Microfluidics • Minimal reagent consumption • Increased speed of reactions • Study of biological phenomena at the single cell level 2

Current Pumps at VIIBRE • Harvard Pico Plus syringe pumps • $2, 000 / pump • Limiting complexity of microfluidic devices 3

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 4

Diagram of the System Pneumatic Valves Christmas Tree Nanophysiometer Fluid Flow Peristaltic Pump 5

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 6

Initial Design of Peristaltic Pump • 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 7

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 8

Flow Rates for Flow Layer Below Control Flow 9

Results with Flow Channel Above Flow Control 10

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 Lab. VIEW program 11

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 t=0 t=d/v Groisman & Quake 2004 12

Lab. VIEW 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 13

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 14

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 Flow Kartalov et al. 2006 15