Patch-Clamping in Droplet Arrays: Single Cell Positioning via Dielectrophoresis

Abstract

This paper reports a new approach to enable patch-clamp recording from living cells in arrays of droplets placed on a microstructured silicon surface. Single cells were positioned on the lateral patch sites by using dielectrophoresis (DEP) electrical force. This approach simplifies the complex packaging process involved when pressure-driven fluidics are used to guide cells through microchannels towards the patching sites. It also enables direct access to the droplets for fluid exchange, opening the way for the gold standard patch-clamp technique to become compatible with the industry standards of high-throughput liquid handling platforms. The microchips contained two 20μm deep chambers etched in silicon and passivated by silicon oxide, holding the reagent droplets, and separated by a 250μm-long buried microchannel with an aperture of around 1μm in diameter. Simulations of a fourelectrode configuration showed that negative DEP could advantageously eliminate the need of any bulk fluid movement and enable single cell positioning in droplets. Working DEP parameters (voltage, frequency) were identified using gold microprobes as external electrodes, dipped in the cell droplets. Single cell positioning at the keyhole was achieved at a speed of about 4μm/s for an optimum cell concentration. © International Federation of Medical and Biological Engineering 2009.