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Microfluidic Multi-Patch Recording Unit. Kachi Odoemene Physiological Sensing Facility Purdue University. Patch Clamp Technique . Measure intracellular current from single ion channels of excitable cells Glass micropipette 1-2um in diameter
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MicrofluidicMulti-Patch Recording Unit Kachi Odoemene Physiological Sensing Facility Purdue University
Patch Clamp Technique • Measure intracellular current from single ion channels of excitable cells • Glass micropipette 1-2um in diameter • Giga-ohm seal formation between glass electrode and cell membrane Closed Open Glass electrode Ion channel Cell Membrane Hamil, O et al 1981 Neher and Sakman 1992
Limitations of Traditional Patch • Operation requires high skill level • Low throughput • Approximately 10 cells/day • Impossible to record from population of neurons in local network http://www.farma.ku.dk/uploads/pics/PatchClamp.jpg
Conceptual Design Backside microfluidic channels Circular Patch Site Access port for electrode and suction tubing PDMS chamber
Patch Substrate Design Top side Back side • Double sided processing on either glass or silicon substrate • Backside: Tapered microfluidic channels • From 10 um wide to 500 um wide • Topside: Patch pores and microtubing access port • Holes aligned to mate with with channel • Application dependent array size and spacing Patch pores 1-2 um diameter
Proof of Device Concept in Silicon • Implement chip design using Deep Reactive Ion Etching (DRIE) • Fast etch rate (>8 um/min) • Wet oxidation to create glass-like layer and shrink patch pores • Integration with PDMS SEM micrographs of microchannels Confocal micrograph of narrow channels
Glass Fabrication • High aspect ratio glass DRIE requires hard mask • Thick electroplated nickel (>5 um) • Very slow etch rate • 0.5 um/min • Currently laser micromachining channels and pores Nickel hard mask patterned with photoresist Channels etched via DRIE, with NI hard mask
Potential Commercial Advantages • Overall unique chip design in glass • Embedded microfluidic channels • Isolated studies of channels of single cell or cells in a network • Glass substrate allowing giga-seal formation & electrical isolation • Recordings from adherent cells in tissue culture and cells with native ion channels • Device automation will lead to high throughput drug screening applications