A PDMS microfluidic system with poly(ethylene glycol)/SU-8 based apertures for planar whole cell-patch-clamp recordings

Poly(dimethylsiloxane) (PDMS) has been used as an attractive material for planar patch-clamp system fabrication. However, the hydrophobic property of PDMS prevents the establishment of a high-resistance seal with cell membrane. Here, we describe the first use of poly(ethylene glycol) (PEG)/SU-8 mixture for patch-clamp partition electrode fabrication. This PEG/SU8 mixture with weight ratio of 1:1 has been proved to have better properties compared with PDMS for cell-patch interface, such as improved mechanical property, permanent hydrophilic surface property, and easiness to achieve high-resistance cell sealing. The PEG/SU-8 partitions with 2 μm apertures were successfully fabricated by employing a two-step process of soft lithography for PDMS mold (thermal curing) and PEG/SU-8 chip (UV light curing). The partitions could be reversibly sealed to the PDMS microfluidic system including electrode solution inlet/outlet, cell manipulation inlet/outlet, cell reservoir, microchannels and microfabricated Ag/AgCl electrodes. The integrated chip was successfully used to trap Hela cells onto 2 μm aperture by a negative pressure. We demonstrated that a planar PDMS patch-clamp system with PEG/SU-8 based cell-patch interface for successful patch-clamp recording on Hela cells.