Towards MEMS Probes for Intracellular Recording

Abstract

Simultaneous, multi-site recording from the brain of freely behaving animals will allow neuroscientists to correlate neuronal activity with external stimulation and behavior. This information is critical for understanding the complex interactions of brain cells. Recent interest in microelectromechanical systems (MEMS) and in particular in bio-MEMS research has led to miniaturization of microelectrodes for extracellular neuronal recording. MEMS technology offers a unique opportunity to build compact, integrated sensors well suited for multi-site recording from freely behaving animals. These devices have the combined capabilities of silicon-integrated circuit processing and thin-film microelectrode sensing. MEMS probes for intracellular recording may offer significantly improved signal quality. Here we discuss the basic concepts that underlie the construction of intracellular MEMS probes. We first review the basics of neuronal signaling and recording, and the principles of microelectrode technology and techniques. Progress in MEMS technology for neuronal recording is then discussed. Finally, we describe MEMS probes for intracellular recording, viz., fabrication of micro-machined silicon needles capable of penetrating cell membranes. Using these needles, we recorded localized extracellular signals from the hawk moth Manduca sexta and obtained first recordings with silicon-based micro-probes from the inside of neurons, using an isolated brain of the sea slug Tritonia diomedea.