• A new brain-computer interface with a fl

    From ScienceDaily@1:317/3 to All on Tuesday, March 15, 2022 22:30:42
    A new brain-computer interface with a flexible backing
    The flexible backing allows arrays of micro-scale needles to conform to
    the contours of the brain, which improves high-resolution brain recording

    Date:
    March 15, 2022
    Source:
    University of California - San Diego
    Summary:
    Engineering researchers have invented an advanced brain-computer
    interface with a flexible and moldable backing and penetrating
    microneedles. Adding a flexible backing to this kind of
    brain-computer interface allows the device to more evenly conform to
    the brain's complex curved surface and to more uniformly distribute
    the microneedles that pierce the cortex. The microneedles,
    which are 10 times thinner than the human hair, protrude from
    the flexible backing, penetrate the surface of the brain tissue
    without piercing surface venules, and record signals from nearby
    nerve cells evenly across a wide area of the cortex. This novel
    brain-computer interface has thus far been tested in rodents.



    FULL STORY ========================================================================== Engineering researchers have invented an advanced brain-computer interface
    with a flexible and moldable backing and penetrating microneedles. Adding
    a flexible backing to this kind of brain-computer interface allows the
    device to more evenly conform to the brain's complex curved surface and
    to more uniformly distribute the microneedles that pierce the cortex. The microneedles, which are 10 times thinner than the human hair, protrude
    from the flexible backing, penetrate the surface of the brain tissue
    without piercing surface venules, and record signals from nearby nerve
    cells evenly across a wide area of the cortex.


    ==========================================================================
    This novel brain-computer interface has thus far been tested in
    rodents. The details were published online on February 25 in the journal Advanced Functional Materials. This work is led by a team in the lab
    of electrical engineering professor Shadi Dayeh at the University of
    California San Diego, together with researchers at Boston University
    led by biomedical engineering professor Anna Devor.

    This new brain-computer interface is on par with and outperforms the "Utah Array," which is the existing gold standard for brain-computer interfaces
    with penetrating microneedles. The Utah Array has been demonstrated
    to help stroke victims and people with spinal cord injury. People with implanted Utah Arrays are able to use their thoughts to control robotic
    limbs and other devices in order to restore some everyday activities
    such as moving objects.

    The backing of the new brain-computer interface is flexible, conformable,
    and reconfigurable, while the Utah Array has a hard and inflexible
    backing. The flexibility and conformability of the backing of the
    novel microneedle-array favors closer contact between the brain and
    the electrodes, which allows for better and more uniform recording
    of the brain-activity signals. Working with rodents as model species,
    the researchers have demonstrated stable broadband recordings producing
    robust signals for the duration of the implant which lasted 196 days.

    In addition, the way the soft-backed brain-computer interfaces are
    manufactured allows for larger sensing surfaces, which means that
    a significantly larger area of the brain surface can be monitored simultaneously. In theAdvanced Functional Materials paper, the researchers demonstrate that a penetrating microneedle array with 1,024 microneedles successfully recorded signals triggered by precise stimuli from the
    brains of rats. This represents ten times more microneedles and ten
    times the area of brain coverage, compared to current technologies.

    Thinner and transparent backings These soft-backed brain-computer
    interfaces are thinner and lighter than the traditional, glass backings of these kinds of brain-computer interfaces. The researchers note in their Advanced Functional Materials paper that light, flexible backings may
    reduce irritation of the brain tissue that contacts the arrays of sensors.



    ==========================================================================
    The flexible backings are also transparent. In the new paper, the
    researchers demonstrate that this transparency can be leveraged to perform fundamental neuroscience research involving animal models that would not
    be possible otherwise. The team, for example, demonstrated simultaneous electrical recording from arrays of penetrating micro-needles as well
    as optogenetic photostimulation.

    Two-sided lithographic manufacturing The flexibility, larger microneedle
    array footprints, reconfigurability and transparency of the backings
    of the new brain sensors are all thanks to the double-sided lithography approach the researchers used.

    Conceptually, starting from a rigid silicon wafer, the team's
    manufacturing process allows them to build microscopic circuits and
    devices on both sides of the rigid silicon wafer. On one side, a flexible, transparent film is added on top of the silicon wafer. Within this film,
    a bilayer of titanium and gold traces is embedded so that the traces
    line up with where the needles will be manufactured on the other side
    of the silicon wafer.

    Working from the other side, after the flexible film has been added,
    all the silicon is etched away, except for free-standing, thin, pointed
    columns of silicon. These pointed columns of silicon are, in fact,
    the microneedles, and their bases align with the titanium-gold traces
    within the flexible layer that remains after the silicon has been etched
    away. These titanium-gold traces are patterned via standard and scalable microfabrication techniques, allowing scalable production with minimal
    manual labor. The manufacturing process offers the possibility of flexible array design and scalability to tens of thousands of microneedles.



    ========================================================================== Toward closed-loop systems Looking to the future, penetrating microneedle arrays with large spatial coverage will be needed to improve brain-machine interfaces to the point that they can be used in "closed-loop systems"
    that can help individuals with severely limited mobility. For example,
    this kind of closed-loop system might offer a person using a robotic hand real-time tactical feedback on the objects the robotic hand is grasping.

    Tactile sensors on the robotic hand would sense the hardness, texture,
    and weight of an object. This information recorded by the sensors would
    be translated into electrical stimulation patterns which travel through
    wires outside the body to the brain-computer interface with penetrating microneedles.

    These electrical signals would provide information directly to the
    person's brain about the hardness, texture, and weight of the object. In
    turn, the person would adjust their grasp strength based on sensed
    information directly from the robotic arm.

    This is just one example of the kind of closed-loop system that could
    be possible once penetrating microneedle arrays can be made larger to
    conform to the brain and coordinate activity across the "command" and "feedback" centers of the brain.

    Previously, the Dayeh laboratory invented and demonstrated the kinds
    of tactile sensors that would be needed for this kind of application,
    as highlighted in this video.

    Pathway to commercialization The advanced dual-side lithographic microfabrication processes described in this paper are patented (US
    10856764). Dayeh co-founded Precision Neurotek Inc.

    to translate technologies innovated in his laboratory to advance state
    of the art in clinical practice and to advance the fields of neuroscience
    and neurophysiology.


    ========================================================================== Story Source: Materials provided by
    University_of_California_-_San_Diego. Note: Content may be edited for
    style and length.


    ========================================================================== Journal Reference:
    1. Sang Heon Lee, Martin Thunemann, Keundong Lee, Daniel R. Cleary,
    Karen J.

    Tonsfeldt, Hongseok Oh, Farid Azzazy, Youngbin Tchoe, Andrew
    M. Bourhis, Lorraine Hossain, Yun Goo Ro, Atsunori Tanaka,
    Kıvılcım Kılıc,, Anna Devor, Shadi
    A. Dayeh. Scalable Thousand Channel Penetrating Microneedle Arrays
    on Flex for Multimodal and Large Area Coverage BrainMachine
    Interfaces. Advanced Functional Materials, 2022; 2112045 DOI:
    10.1002/adfm.202112045 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/03/220315165029.htm

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