System for multichannel recording of the electrophysiological activity of a brain tissue in-vivo

In this paper we present a measurement system for multichannel recordings of the electrophysiological activity of brain tissue in vivo. The system consists of: penetrating Microelectrode Array (MEA), three versions of a Conditioning Module each equipped with different Application Specific Integrated Circuits (ASIC's), Digitizer and PC Application for recorded data presentation and storage. The MEA consists of 64 15 µm diameter microelectrodes. The multichannel ASIC's amplify and filter field and action potential signals. The custom-made Digitizer Module simultaneously acquires data from all channels with a 14 kS/s sample rate and 12 bit resolution. The resulting byte stream (about 2 MB/s) is transmitted to the PC via USB (Universal Serial Bus). Eventually the measurement data is decoded, presented to the system user and stored on a HDD. Preliminary in-vivo measurements confirm that the system is capable of a multipoint recording of action potentials with amplitude down to 50uV.