Mammalian electrophysiology on a microfluidic platform

The recent development of automated patch clamp technology has increased the throughput of electrophysiology but at the expense of visual access to the cells being studied. To improve visualization and the control of cell position, we have developed a simple alternative patch clamp technique based on microfluidic junctions between a main chamber and lateral recording capillaries, all fabricated by micromolding of polydimethylsiloxane (PDMS). PDMS substrates eliminate the need for vibration isolation and allow direct cell visualization and manipulation using standard microscopy. Microfluidic integration allows recording capillaries to be arrayed 20 mu m apart, for a total chamber volume of < 0.5 nl. The geometry of the recording capillaries permits high-quality, stable, whole-cell seals despite the hydrophobicity of the PDMS surface. Using this device, we are able to demonstrate reliable whole-cell recording of mammalian cells on an inexpensive microfluidic platform. Recordings of activation of the voltage-sensitive potassium channel Kv2.1 in mammalian cells compare well with traditional pipette recordings. The results make possible the integration of whole-cell electrophysiology with easily manufactured microfluidic lab-on-a-chip devices.