The past decade’s boom in robotic and prosthetic technologies have brought high-speed, multi-articulating devices to laboratories worldwide, but not to consumers. One of the major barriers to widespread usage among people with severe mobility limitations is the technological dearth of high-fidelity connective devices that can communicate between a user’s brain and a device. Now, researchers have produced a prototype that could lead to long-lasting, less invasive, bio-integrated electronic sensors. A team led by Brian Litt, MD, and John A. Rogers, PhD, have developed an ultra-thin, flexible brain implant with a biodegrading, biocompatible silk backing that can be timed to “melt” away at a given time, leaving the electronics lying flush on the curved surface of the brain.
“Electronics that are capable of intimate, non-invasive integration with the soft, curvilinear surfaces of biological tissues offer important opportunities for diagnosing and treating disease and for improving [brain-computer] interfaces [BCIs],” the authors wrote in the April 2010 Nature Materials. Their device offers what they term a “bio-interfaced system that relies on ultrathin electronics supported by bioresorbable substrates of silk fibroin. Mounting such devices on tissue and then allowing the silk to dissolve and resorb initiates a spontaneous, conformal wrapping process driven by capillary forces at the biotic/abiotic interface. Specialized mesh designs and ultrathin forms for the electronics ensure minimal stresses on the tissue and highly conformal coverage, even for complex curvilinear surfaces.”
These devices would beat out the current standard, needle-probe sensors. Such sensors can cause rapid degradation of brain tissue and are considered unsafe for long-term use. The silk-based implants could not only drive prostheses, but potentially even re-route nerve signals around broken sections of a spinal cord, according to Gizmag writer Darren Quick. Seizure-detection and prevention devices might also arise from such sensors.
“The absence of sharp electrodes and rigid surfaces found on current brain implants should improve safety, with less damage to brain tissue,” Quick wrote. “Also, the implants’ ability to mold to the brain’s surface could provide better stability. If the brain shifts in the skull, the implant could move with it. Finally, by spreading across the brain, the implants have the potential to capture the activity of large networks of brain cells.”
The silk substrate brings unusual properties to the sensor. Though strong enough to withstand being coated with the metal electrode, it can be engineered to dissolve in the body within a certain window of time, starting soon after implantation and stretching years into the future.