Engineering researchers have invented a sophisticated brain-computer interface with a flexible and moldable backing and penetrating microneedles. Adding a flexible backing to this type of brain-computer interface allows the system to extra evenly conform to the brain’s advanced curved floor and to extra uniformly distribute the microneedles that pierce the cortex. The microneedles, which are 10 occasions thinner than the human hair, protrude from the flexible backing, penetrate the floor of the brain tissue with out piercing floor venules, and report indicators from close by nerve cells evenly throughout a large space of the cortex.
This novel brain-computer interface has to this point been examined in rodents. The particulars have been revealed on-line on February 25 in the journal Advanced Functional Materials. This work is led by a group in the lab of electrical engineering professor Shadi Dayeh at the University of California San Diego, along 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 present gold customary for brain-computer interfaces with penetrating microneedles. The Utah Array has been demonstrated to assist stroke victims and folks with spinal wire harm. People with implanted Utah Arrays are in a position to use their ideas to management robotic limbs and different units so as to restore some on a regular basis actions reminiscent of transferring objects.
The backing of the new brain-computer interface is flexible, conformable, and reconfigurable, whereas the Utah Array has a tough and rigid backing. The flexibility and conformability of the backing of the novel microneedle-array favors nearer contact between the brain and the electrodes, which allows for higher and extra uniform recording of the brain-activity indicators. Working with rodents as mannequin species, the researchers have demonstrated secure broadband recordings producing strong indicators for the period of the implant which lasted 196 days.
In addition, the approach the soft-backed brain-computer interfaces are manufactured allows for bigger sensing surfaces, which implies that a considerably bigger space of the brain floor could be monitored concurrently. In the Advanced Functional Materials paper, the researchers exhibit {that a} penetrating microneedle array with 1,024 microneedles efficiently recorded indicators triggered by exact stimuli from the brains of rats. This represents ten occasions extra microneedles and ten occasions the space of brain protection, in contrast to present applied sciences.
Thinner and clear backings
These soft-backed brain-computer interfaces are thinner and lighter than the conventional, glass backings of these sorts of brain-computer interfaces. The researchers notice of their Advanced Functional Materials paper that gentle, flexible backings could scale back irritation of the brain tissue that contacts the arrays of sensors.
The flexible backings are additionally clear. In the new paper, the researchers exhibit that this transparency could be leveraged to carry out elementary neuroscience analysis involving animal fashions that will not be doable in any other case. The group, for instance, demonstrated simultaneous electrical recording from arrays of penetrating micro-needles in addition to optogenetic photostimulation.
Two-sided lithographic manufacturing
The flexibility, bigger microneedle array footprints, reconfigurability and transparency of the backings of the new brain sensors are all thanks to the double-sided lithography method the researchers used.
Conceptually, ranging from a inflexible silicon wafer, the group’s manufacturing course of allows them to construct microscopic circuits and units on each side of the inflexible silicon wafer. On one facet, a flexible, clear movie is added on high of the silicon wafer. Within this movie, a bilayer of titanium and gold traces is embedded in order that the traces line up with the place the needles shall be manufactured on the different facet of the silicon wafer.
Working from the different facet, after the flexible movie has been added, all the silicon is etched away, aside from free-standing, skinny, pointed columns of silicon. These pointed columns of silicon are, in reality, the microneedles, and their bases align with the titanium-gold traces inside the flexible layer that is still after the silicon has been etched away. These titanium-gold traces are patterned by way of customary and scalable microfabrication methods, permitting scalable manufacturing with minimal guide labor. The manufacturing course of affords the risk of flexible array design and scalability to tens of hundreds of microneedles.
Toward closed-loop programs
Looking to the future, penetrating microneedle arrays with giant spatial protection shall be wanted to enhance brain-machine interfaces to the level that they can be utilized in “closed-loop systems” that may assist people with severely restricted mobility. For instance, this type of closed-loop system may supply an individual utilizing a robotic hand real-time tactical suggestions on the objects the robotic hand is greedy.
Tactile sensors on the robotic hand would sense the hardness, texture, and weight of an object. This info recorded by the sensors can be translated into electrical stimulation patterns which journey by way of wires exterior the physique to the brain-computer interface with penetrating microneedles. These electrical indicators would supply info instantly to the particular person’s brain about the hardness, texture, and weight of the object. In flip, the particular person would regulate their grasp energy primarily based on sensed info instantly from the robotic arm.
This is only one instance of the type of closed-loop system that might be doable as soon as penetrating microneedle arrays could be made bigger to conform to the brain and coordinate exercise throughout the “command” and “feedback” facilities of the brain.
Previously, the Dayeh laboratory invented and demonstrated the sorts of tactile sensors that will be wanted for this type of software, as highlighted on this video.
Pathway to commercialization
The superior dual-side lithographic microfabrication processes described on this paper are patented (US 10856764). Dayeh co-founded Precision Neurotek Inc. to translate applied sciences innovated in his laboratory to advance state of the artwork in medical observe and to advance the fields of neuroscience and neurophysiology.
