This is a flexible mesh circuitry that Harvard nanotechnologists have injected via syringe into the heads of live mice to test a new way of monitoring brain signals from the inside.
Eventually, such technology could lead to new treatments for Parkinson's disease or mind-controlled prosthetic limbs. From Smithsonian:
Autopsies of injected mice revealed that the wires had woven themselves into the tangled fabric of neurons over the course of weeks. Tight connections formed as plastic and brain matter knitted together with seemingly little negative impact.
The neurons' activities could be monitored using microscopic sensors wired into the circuit. Voltage detectors picked up currents generated by individual brain cells firing. Those electrical signals were relayed along a wire running out of the head to a computer…
"We have to walk before we can run, but we think we can really revolutionize our ability to interface with the brain," says (lead researcher Charles) Lieber.