Seal Formation in Silicon Planar Patch-Clamp Microstructures

This paper presents a microfabricated planar patch-clamp electrode design and looks at the impact of several physical characteristics on seal formation. The device consists of a patch aperture, 1.5–2.5 $muhbox{m}$ in diameter and 7–12 $muhbox{m}$ in depth, with a reverse-side deep-etched 80- $muhbox{m}$ well. The patch aperture was coated with either thermal oxide or plasma-enhanced chemical vapor deposited (PECVD) $ hbox{SiO}_{2}$. Some of the thermal oxide devices were converted into protruding nozzle structures, and some were boron-doped. Seal formation was tested with cultured N2a neuroblastoma cells. The PECVD oxide devices produced an average seal resistance of 34 $hbox{M}Omega (n = 24)$ , and the thermal oxide devices produced an average seal resistance of 96 $hbox{M}Omega (n = 59)$. Seal resistance was found to positively correlate with patch aperture depth. Whole-cell recordings were obtained from 14% of cells tested with the thermal oxide devices, including a single recording where a gigaohm seal was obtained.$hfill$ 2007-0159]