Development of a Modular Peristaltic Microfluidic Pump and Valve System 3/13/2007 BME 273 Group 20: Adam Dyess, Jake Hughey, Michael Moustoukas, Matt Pfister

2 Microfluidics for Biology Reduced reagent consumption Precise control of microenvironment Study of biological phenomena at the single cell level

3 Microfluidics at VIIBRE Immunology  T cell signaling & activation, proliferation, and cycling Chemotaxis  Traction force & cell migration Cell Forces  Traction force bed of nails & cell to cell adhesion Haptotaxis  Rapid generation of protein gradients on a substrate Cancer  Angiogenesis & Metastasis bioreactors Biodefense  Metabolic dynamics for toxic discrimination Ionomycin-induced Ca ++ cycling in T cells

4 Current Pumps at VIIBRE Harvard Pico Plus syringe pumps $2,000 / pump Difficult to avoid bubbles Limiting complexity of microfluidic devices

5 Ideal On-chip Pumping System Switch flow rates from a minimum of 50 nl/min to a maximum of 300 nl/min with an accuracy of 10 nl/min Rotate between 4 different solutions in milliseconds with no leakage Minimize cost of materials (<$200) Immediate needs  Flow recirculation  Some experiments require a complete fluidic circuit on-chip Long-term  Point of care device

6 Pressure Vacuum Parallel Port Connection Nanophysiometer Cell Loader Polyphase PumpTrapped Cells Via Basic Schematic Microfluidic Device Input Channels

7 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

8 Polyphase Pump Each pump has four valves in series Flow channel  100 µm wide, 10 µm tall (round) Control channel  25 µm tall, valve area is 300 µm by 300 µm Four pumps in parallel Increase flow rate Reduce flow rate oscillations Air compressor provides vacuum in the off state

9 Flow Channel Below (1→4) Control Flow Flow rates measured by bubble displacement in output tubing

10 Flow Channel Above (1→4→1) Control Flow

11 Latest Version of Polyphase Pump Multiple fluid inputs Valves to selectively block individual lanes Flow rate tester 100 µm or 200 µm wide flow channels Calls for controller box with at least 9 inputs Requires extension of LabVIEW program

12 12 Valve Controller Schematic Using Altium Designer Parallel Port Optocoupler Resistors Transistors Diodes 2-pin Header Amplifier

13 12 Valve Controller Printed Circuit Board Vendor: Advanced Circuits Cost: $40/PCB Arrival: Friday Circuit Components Parts: 47 + Box + tubing Cost: ~$100 / controller Arrival: Friday PCB designed in Protel 4.5” 2.312”

14 LabVIEW Interface Integrate Excel spreadsheet into LabView controls Spreadsheet controls valves (on/off), duration of trial, repetition NI clock to guarantee timing Empirically correlate pump speed with actuation frequency

15 Current Work Optimize fabrication procedures for new pump design Y junctions and steel needles for easier pump assembly Fabrication of microfluidic vias Measure flow rate vs. outlet pressure head Characterize flow oscillations  Pulse-chase with bolus of fluorescent solution  Head to head vs. syringe pump Groisman & Quake 2004 t = 0 t = d / v Kartalov et al Flow

16 Future Work Investigate influence of downstream resistance Effect of membrane thickness on performance and durability of pumps Increase aspect ratio of flow channels Incorporate gradient device or T cell device on chip with pump PDMS Film Thickness PDMS thickness measured using displacement gauge