Compact voltage and current stimulation buffer for high-density microelectrode arrays

The most sophisticated information processing system, the human brain, consists of a huge number of neurons that form part of an intricate network and communicate through electrical and chemical signals via synapses. To elucidate interneuronal communication and network characteristics, it is important to gain bidirectional access (recording and stimulation) to individual neurons and to be able to do closed-loop experiments in cultures. The targeted stimulation of individual neurons, and the subsequent tracking of a signal's propagation is a valuable tool to decipher network structures as well as strength and plasticity of involved connections. CMOS-based microelectrode arrays (MEAs) featuring high spatial resolution (subcellular) and low noise provide a wealth of information. Extracellular electrodes ensure cell integrity and long-term recordings; neuronal stimulation is performed by either current or voltage pulses, with typical amplitudes of 0.1 to 1V or 5 to 10µA, and durations of 50 to 900µs [1].