256-Channel Neural Recording and Delta Compression Microsystem With 3D Electrodes

A 3D microsystem for multi-site penetrating extracellular neural recording from the brain is presented. A 16 times 16-channel neural recording interface integrated prototype fabricated in 0.35 mum CMOS occupies 3.5 mm times 4.5 mm area. Each recording channel dissipates 15 muW of power with input-referred noise of 7 muV_rms over 5 kHz bandwidth. A switched-capacitor delta read-out data compression circuit trades recording accuracy for the output data rate. An array of 1.5 mm platinum-coated microelectrodes is bonded directly onto the die. Results of in vitro experimental recordings from intact mouse hippocampus validate the circuit design and the on-chip electrode bonding technology.