320-Channel Active Probe for High-Resolution Neuromonitoring and Responsive Neurostimulation

We present a 320-channel active probe for high-spatial-resolution neuromonitoring and responsive neurostimulation. The probe comprises an integrated circuit (IC) cell array bonded to the back side of a pitch-matched microelectrode array. The IC enables up to 256-site neural recording and 64-site neural stimulation at the spatial resolution of 400 mu m and 200 mu m, respectively. It is suitable for direct integration with electrode arrays with the shank pitch of integermultiples of 200 mu m. In the presented configuration, the IC is bonded with a 8 x 8 400 mu m-pitch Utah electrode array (UEA) and up to additional 192 recording channels are used for peripheral neuromonitoring. The 0.35 mu m CMOS circuit array has a total die size of 3.5 mm x 3.65 mm. Each stimulator channel employs a current memory for simultaneous multi-site neurostimulation, outputs 20 mu A-250 mu A square or arbitrary waveformcurrent, occupies 0.02 mm(2), and dissipates 2.76 mu Wquiescent power. Each fully differential recording channel has two stages of amplification and filtering and an 8-bit single-slope ADC, occupies 0.035mm(2), and consumes 51.9 mu W. The neural probe has been experimentally validated in epileptic seizure propagation studies in a mouse hippocampal slice in vitro and in responsive neurostimulation for seizure suppression in an acute epilepsy rat model in vivo.