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Nosotros've seen some pretty impressive results with brain-computer interfaces based on pincushion arrays of stiff electrodes. Nonetheless, a major problem with these arrays is that they are temporary. Natural events in the brain inexorably degrade the connection between the living and the non-living until the device ceases to operate, and needs to be extracted. If we may draw a brief parallel here with the nuclear power industry, there is typically much more enthusiasm for installation of devices like these than there is for their removal.

At that place are two main processes responsible for the relatively brusk electrode lifetime. The first tin can be summed up every bit "reactive gliosis." In a nutshell, the neurons you desire to record from are somewhen displaced from the electrode surfaces past more ambitious glial cells. The 2d major event is that the natural movements of the brain further aggravate this displacement. The combined actions of heart, lungs, volume changes, and body movements wear on the tenous neuron connections until they are compromised.

nanowires

Researchers at Lund University have been developing new electrode technologies to accost both of these issues. To solve the glial jail cell issue, i team has built 3D nanostructured axon guides out of gallium phosphide (GaP). The fundamental innovation here is to create a vertically-oriented bed of 80nm bore nanowires that preferentially exclude the glia, and back up the axons. As described in their recent publication in Applied Materials and Interfaces, the squad built their devices using a combination of electron beam lithography and metallic organic vapor phase epitaxy, a chemical process used to make thin films. GaP, every bit some may recognize, is the stuff of LEDs. Pure GaP LEDs emit greenish and doping them with nitrogen or zinc oxide generates a few additional colors.

The GaP is used hither purely equally a substrate. They is no fancy optogenetic applications, for example, still incorporated. To convert the GaP base into an electrode, researchers would typically metalize the contact surfaces with with a thin motion picture of something like gold. The researchers patterned the GaP into strips where the glial cells generally stayed in the valleys in betwixt. It is not notwithstanding fully understood why the neurites prefer the nanowire topology, or why the glial don't, just it seems that the more motile and mitotically agile glial do better on the flat areas.

In the meantime, some other group at Lund University has been working on the motion artifact trouble. They too have new work to report, this fourth dimension in the Periodical Frontiers in Neuroscience. Their approach is to employ a soft paralene insulator cloth over a light amplification by stimulated emission of radiation-milled gold electrode core. As the video below shows, their electrodes are encased in a rigid biodegradeable gelatin beat that provides stiffness when the electrode gets inserted. Afterwards the shell is dissolved to betrayal the flexible electrode.

These two technologies are fairly dissimilar and at to the lowest degree initially will probable have unlike applications. The GaP electrodes had first been shown to piece of work in the peripheral nervous system. In the study mentioned here, the researchers used a civilization of glia and retinal ganglion cells. These neurons generate the optic nervus, which technically speaking is the only 'cranial nerve' considered to exist office of the cardinal nervous system. This qualification comes forth with all the protections and nourishments of the meninges that sheet the encephalon. It too includes the uniquely central myelinating system comprised of oligodendrocytes, as opposed to the peripheral Schwann cells. This is why, for example, we observe central maladies like Optic Neuritis in Multiple Sclerosis, simply not peripheral neuropathy like Guillain-Barré syndrome affecting the optic nervus.

It remains to exist seen whether optic fretfulness growing on these different kinds of electrodes would be readily myelinated in the context of a GaP device. The researchers will no uncertainty exist anxious to test their device equally an implant rather than just in civilization, and to integrate information technology with other technologies to extend its operation.