Enabling SNN-based near-MEA neural decoding with channel selection: an open-HW approach

Advancements in CMOS microelectrode array sensors have significantly improved sensing area and resolution, paving the way to accurate Brain-Machine Interfaces (BMIs). However, near-sensor neural decoding on implantable computing devices is still an open problem. A promising solution is provided by Spiking Neural Networks (SNNs), which leverage event sparsity to improve energy consumption. However, given the typical data rates involved, the workload related to I/O acquisition and spike encoding is dominant and limits the benefits achievable with event-based processing. In this work, we present two power-efficient implementations, on FPGA and ASIC, of a dedicated processor for the decoding of intracortical action potentials from primary motor cortex. The processor leverages lightweight sparse SNNs to achieve state-of-the-art accuracy. To limit the impact of I/O transfers on energy efficiency, we introduced a channel selection scheme that reduced bandwidth requirements by 3x and power consumption by 2.3x and 1.6x on the FPGA and ASIC, respectively, enabling inference at 0.446 μJ and 1.04 μJ, with no significant loss in accuracy. To promote broad adoption in a specialized, research-intensive domain, we have based our implementations on open-source EDA tools, low-cost hardware, and an open PDK.