Ultra-stable glass microcraters for on-chip patch clamping

We report on a single-step fabrication procedure of borosilicate glass micropores surrounded by a smooth microcrater. By inserting a thin air-gap between a borosilicate glass substrate and a reflective layer, we achieve dual-sided laser ablation of the device. The resultant crater provides a smoother, curved surface onto which cells settle during planar patch clamping. Gigaohm seals, which are more easily achievable on these devices as compared to conventional micropores, are achieved by patch clamping human embryonic kidney (HEK 293) cells. Further, the microcraters show enhanced mechanical stability of the planar patch clamped cells during perfusion. We integrate polydimethylsiloxane microfluidic devices with the microcraters and use passive pumping to perfuse the cells. We find that passive pumping increases the pressure within the device by 1.85 Pa. However, due to the enhanced stability of the microcrater, fluidic shearing reduces the seal resistance by only 6.8 MΩ on average, which is less than one percent of the gigaohm seal resistance.