Development of flexible μECoG electrode arrays for chronic use in brain cavities

And maybe with this our researchers could listen in on neuron signalling and figure out precisely how neuroplasticity works. Why would a neuron give up its current job and switch careers to a neighboring neuron?
https://lirias.kuleuven.be/handle/123456789/457677

Authors:	Ceyssens, Frederik van Kuyck, Kris Deprez, Marjolijn Nica, Ioana Gabriela Aerts, Jean-Marie Nuttin, Bart Puers, Bob
Issue Date:	Jun-2014
Conference:	Neural Interfacing Conference location:Dallas date:June 2014
Abstract:	Ultra-flexible thin film microelectrode arrays were designed, fabricated and tested in vitro and in vivo, aiming at μEcoG and neurostimulation applications in the wall of brain cavities arising after e.g. hemorrhage or tumor resection. In order to conform to cavity walls and to minimize irritation, the arrays were designed in a tree or web shape for high bendability over a 5 mm radius sphere. Compared to an unpatterned sheet, the required bending energy per area was reduced by 95%. The very low total thickness of 7 μm further adds to the bendability. The arrays carry 100 μm and 350 μm diameter electrodes, for a charge injection capacity of 75 μC/phase/cm2 for Pt and 2000 μC/phase/cm2 for sputtered IrOx. Fabrication was done using lithographic techniques. The arrays consist of a polyimide-Pt-polyimide structure. An improved fabrication process was designed in order to enhance insulation lifetime in a saline environment. In accelerated aging tests at 87 degrees C, this process has been shown to improve lifetime by a factor 7.4 comparing to the state of the art. Similar lifetime tests were done to select the connector's underfill isolation. Finally, in vivo tests in freely moving rats have shown satisfying operation of the implants in neural recording and stimulation over a period of at least 3 months.