A complete 256-channel reconfigurable system for in vitro neurobiological experiments

We present a complete reconfigurable measurement system for 256-channel in vitro recordings and electrical stimulation of brain tissue electrophysiological activity. The system is built of: brain tissue life support system, Microelectrode Array (MEA), 4 multichannel integrated electronic circuits for signals conditioning and electrical stimulation, Digitizer and PC Application for measurement, data presentation and storage. The life support system is responsible for keeping brain tissue samples in appropriately saturated artificial cerebrospinal fluid at a very stable temperature. We designed two versions of the ASIC's that can be easily adopted to the system. These are processed in the CMOS 180nm technology and differ with the main parameters that suits for different types of experiments. The ASIC's are dedicated to amplification, filtering, and electrical stimulation of the 256 channels while the Digitizer performs simultaneous data acquisition from 256 channels with 14 kS/s sample rate and 12bit resolution. The resulting byte stream is transmitted to PC via USB (Universal Serial Bus). We also show a neurobiological experiment results that confirm the system is able to keep the extracted brain tissue active (posterior hypothalamic slices) and to record local theta field potentials with very small amplitudes from multiple neurons simultaneously.