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 integer multiples of 200 $\mu$ m. In the presented configuration, the IC is bonded with a 8 $\,\times\,$ 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 $\,\times\,$ 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 waveform current, occupies 0.02 mm $^{2}$ , and dissipates 2.76 $\mu$ W quiescent power. Each fully differential recording channel has two stages of amplification and filtering and an 8-bit single-slope ADC, occupies 0.035 mm $^{2}$ , 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 .