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

2 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

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

6 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

7 4 pneumatic valves in series Control pressure 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

8 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

9 Flow Rates for Flow Layer Below Control Flow

10 Results with Flow Channel Above Control Flow

11 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

12 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

13 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

14 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

15 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 Flow