‘Neural dust’ brain implants could revolutionize brain-machine interfaces and allow large-scale data recording

from StratRisks.com: In a potential neuroscience breakthrough, University of California
Berkeley scientists have proposed a system that allows for thousands of
ultra-tiny “neural dust” chips to be inserted into the brain to monitor
neural signals at high resolution and communicate data highly
efficiently via ultrasound.

The neural dust design promises to overcome a serious limitation of
current invasive brain-machine interfaces (BMI): the lack of an
implantable neural interface system that remains viable for a lifetime.
Current BMI systems are also limited to several hundred implantable
recording sites, they generate tissue responses around the implanted
electrodes  that degrade recording performance over time, and are
limited to months to a few years.

Neural dust could also provide the large-scale recording of neurons
required for the Brain Research through Advancing Innovative
Neurotechnologies (BRAIN) initiative, the scientists suggest.

System Concept:

Neural dust system diagram showing the
placement of ultrasonic transceiver under the skull, the neural dust
sensing nodes dispersed throughout the brain, and external transceiver
(credit: Dongjin Seo et al.)

The neural dust system has three basic elements:

  • Thousands of low-power CMOS chips — neural dust — are embedded (via
    fine-wire arrays that are then removed) into the cortex between neurons.
    They detect extracellular electrophysiological signals via an electrode
    and a piezoelectric sensor converts ithe signals into ultrasonic
  • A subdural (the dura surrounds the brain and keeps in the
    cerebrospinal fluid) ultrasonic transceiver (transmitter+receiver)
    receives ultrasonic signals from the neural dust.It also powers the
    neural dust with ultrasonic energy.
  • A battery-powered external transceiver communicates via ultrasound
    with the subdural transceiver and transmits the data to an external

Embedded ~2 mm. in the brain, the powered neural dust chips can be as
small as tens of microns (millionths of a meter). Ultrasound is
attractive for in-tissue communication given its short wavelength and
low attenuation.

The design also uses more efficient “backscatting”: instead of
transmitting energy, the chips passively modulate ultrasonic energy from
the sub-dural transceiver and reflect it back.

The researchers calculate that the neural dust chips can be as much
as 10 million times more efficient that chips using electromagnetics
(magnetic or electric signals), which have high attenuation in brain
tissue. They would be encapsulated in an inert polymer or insulator film.

The arXiv paper mentions a number of challenges that need to be addressed in developing a practical system.

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