Long-term wireless, implantable brain-computer interface in Pigs and Monkeys

Researchers at Brown University have succeeded in creating the first wireless, implantable, rechargeable, long-term brain-computer interface. The wireless BCIs have been implanted in pigs and monkeys for over 13 months without issue, and human subjects are next.

Inside there’s a li-ion battery, an inductive (wireless) charging loop, a chip that digitizes the signals from your brain, and an antenna for transmitting those neural spikes to a nearby computer. The BCI is connected to a small chip with 100 electrodes protruding from it, which, in this study, was embedded in the somatosensory cortex or motor cortex. These 100 electrodes produce a lot of data, which the BCI transmits at 24Mbps over the 3.2 and 3.8GHz bands to a receiver that is one meter away. The BCI’s battery takes two hours to charge via wireless inductive charging, and then has enough juice to last for six hours of use.

One of the features that the Brown researchers seem most excited about is the device’s power consumption, which is just 100 milliwatts. For a device that might eventually find its way into humans, frugal power consumption is a key factor that will enable all-day, highly mobile usage.

They are working on reducing the device’s size, improving its safety and reliability, and increasing the amount of data it can transmit — for the eventual goal of equipping those with movement disabilities, or elective transhumanists, with a wireless brain-computer interface.

Brown’s wireless BCI, fashioned out of hermetically sealed titanium, looks a lot like a pacemaker

Journal of Neural Engineering – An implantable wireless neural interface for recording cortical circuit dynamics in moving primates

ABSTRACT

Neural interface technology suitable for clinical translation has the potential to significantly impact the lives of amputees, spinal cord injury victims and those living with severe neuromotor disease. Such systems must be chronically safe, durable and effective. Approach. We have designed and implemented a neural interface microsystem, housed in a compact, subcutaneous and hermetically sealed titanium enclosure. The implanted device interfaces the brain with a 510k-approved, 100-element silicon-based microelectrode array via a custom hermetic feedthrough design. Full spectrum neural signals were amplified (0.1 Hz to 7.8 kHz, 200× gain) and multiplexed by a custom application specific integrated circuit, digitized and then packaged for transmission. The neural data (24 Mbps) were transmitted by a wireless data link carried on a frequency-shift-key-modulated signal at 3.2 and 3.8 GHz to a receiver 1 m away by design as a point-to-point communication link for human clinical use. The system was powered by an embedded medical grade rechargeable Li-ion battery for 7 h continuous operation between recharge via an inductive transcutaneous wireless power link at 2 MHz. Main results. Device verification and early validation were performed in both swine and non-human primate freely-moving animal models and showed that the wireless implant was electrically stable, effective in capturing and delivering broadband neural data, and safe for over one year of testing. In addition, we have used the multichannel data from these mobile animal models to demonstrate the ability to decode neural population dynamics associated with motor activity. Significance. We have developed an implanted wireless broadband neural recording device evaluated in non-human primate and swine. The use of this new implantable neural interface technology can provide insight into how to advance human neuroprostheses beyond the present early clinical trials. Further, such tools enable mobile patient use, have the potential for wider diagnosis of neurological conditions and will advance brain research.

In summary, we have reported on the development of a new wireless, chronically implantable neural interface technology, enabling broadband recordings to be made by an implant over a high-speed radio-frequency link in untethered animals. The work is pertinent to the next generation of neural prostheses for severely neurologically impaired human patients with the final goal of endowing them with significantly increased mobility and wireless access to assistive device technologies. As a proof of device performance and viability, the neural interface was implanted in the primary somatosensory cortex (SI) of two Yorkshire swine and the primary motor cortex (MI) of two rhesus macaque primates. In swine, 100 input channels of broadband neural data were recorded during spontaneous activity and used for device verification and validation over 13 months combined. In primates, 100 input channels containing neural data were simultaneously recorded over 27 months combined. In addition, broadband neural data were collected outside the animals’ home cages, enabling analysis for the reconstruction of motor cortical neural state trajectories during specific naturalistic movements. Moreover, this early mobile collection of neural data prompts the question of how to build future behavioral tasks to elucidate currently not-understood dynamics of the cortex. The high fidelity recording of both spikes and local field potentials suggests that the implantable device can enrich fundamental brain science in primates under naturalistic, freely moving conditions. Our introduction of a wireless interface capable of untethered broadband neural data collection beckons use in other clinical diagnostic applications such as epilepsy monitoring where, currently, patients are tethered to the bedside during neurological assessment.

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