A 25 Mbps, 12.4 pJ/b DQPSK Backscatter Data Uplink for the NeuroDisc Brain-Computer Interface

Area of Science:

• Neuroscience
• Electrical Engineering
• Biomedical Engineering

Background:

• Wireless brain-computer interfaces (BCIs) are crucial for studying neural activity in freely moving non-human primates (NHPs).
• High energy consumption of traditional active radios limits the duration and data rate of wireless BCIs.
• Continuous, high-rate data uplinks are essential for long-term neural monitoring.

Purpose of the Study:

• To present a novel differential quadrature phase shift keying (DQPSK) backscatter uplink for the NeuroDisc BCI.
• To overcome the limitations of active radios in terms of power consumption and data throughput.
• To enable longer-duration, high-rate neural data acquisition in NHPs.

Main Methods:

• Development and implementation of a DQPSK backscatter uplink operating in the 915 MHz ISM band.
• Integration of the uplink with the NeuroDisc BCI system capable of recording 16 channels at 20 kSps per channel.
• System enhancements including an ultra-high frequency (UHF) antenna and a full-duplex receiver for increased bandwidth and signal clarity.

Main Results:

• Achieved a 25 Mbps throughput with a power consumption of 309 μW, yielding an analog communication efficiency of 12.4 pJ/bit.
• The DQPSK backscatter modulator demonstrated an error-vector magnitude (EVM) of 9.7%.
• Validated the system through end-to-end characterization and in vivo recordings from a pigtail macaque.

Conclusions:

• The DQPSK backscatter uplink offers a power-efficient alternative to active radios for wireless BCIs.
• This technology significantly enhances the capabilities for long-term neural recording in NHPs.
• The innovations in antenna design and receiver technology enable higher bandwidth and improved system performance.