INTEGRATED SILICON MICROPIPETTES FOR PATCH CLAMP APPLICATIONS

Abstract

Patch clamping the electrophysiological properties of cells. Conventional patch clamp experiments require the careful manipulation of a glass micropipette to the membrane of an isolated cell under high power microscopy. Whilst the process is laborious, the exquisite sensitivity of the patch clamp technique allows the measurement of ionic currents in the order of Pico Amperes across the cellular membrane, enabling the patch clamp technique to serve as an invaluable tool for drug screening. There has thus been considerable effort to automate and miniaturize existing patch clamping equipment to improve its throughput. Through the use of micro fabrication technology an array of micropipettes can be fabricated on a single chip, providing benefits such as reduced reagent usage and enhanced throughput. A microfabricated patch clamp chip that was designed based on previous work done by Yobas et al that allows the creation of sub-surface lateral openings within the silicon substrate. These openings allow the creation of silicon-based micropipettes that serve as replacements for conventional glass micropipettes. Additional device features were integrated with the silicon micropipettes to facilitate cell handling and to reduce the requirement for machine vision and automated cell positioning. The chips were fabricated using a single mask fabrication process involving of a deep reaction ion etch, sidewall passivation and a isotropic etch step using the facilities at the Institute of Microelectronics. Micron-sized circular openings critical to the pipette operation were successfully created and characterized.