A 1 Mbps 158 pJ/bit Bluetooth Low Energy (BLE) Compatible Backscatter Communication Uplink for Wireless Neural Recording in an Animal Cage Environment

Neuroscience research in non-human primates (NHPs) would benefit from multi-day neural recordings from freely moving animals in unconstrained home cage environments. However, wireless brain-computer interfaces (BCI) face two major challenges. First, a metal animal cage forms a reverberant cavity that leads to dense multipath, impairing the wireless communication channel. Second, the battery life of existing wireless neural recording devices is limited by the energy consumption of the neural data uplink.In this paper, we characterize the channel transfer function of a metal NHP home cage in the 2.4 GHz industrial, scientific, and medical (ISM) band, and demonstrate that there is adequate signal strength and bandwidth to support low-power Bluetooth Low Energy (BLE) compatible backscatter data uplinks. For a typical cage and antenna system, the measured maximum insertion loss of the cage-antenna system was 27.4 dB and the minimum -3 dB bandwidth was 5.0 MHz. We demonstrate a 1 Mbps BLE compatible backscatter communication link achieving a worst-case packet error rate of 1.05%, yielding an effective bit error rate of 5.6×10^-5, exceeding the BLE requirement of ≤ 10^-3. The backscatter link has a measured energy consumption of 158 pJ/bit, compared with ≈ 10nJ/bit for existing WiFi and Bluetooth chipsets.