Synthetic Neural Interface

Ever since Hans Berger's discovery of electrical activity inside the human brain, scientists have dreamed of restoring the functionality of damaged sensory organs.  Restoring a specific functionality, vision, is of particular interest to our group.  Previous attempts have not been completely bio-compatible or energy efficient.  This is due to the fact that the classical method of neural stimulation has been to send an electrical current through metal electrodes.  This method is not only unsafe in the long run (due to the electroplating of biological tissue) but most of the current is shunted into surrounding tissue instead of reaching the target cell. This requires sending significantly more current through neural tissue that would otherwise be needed.

It has been established that a neural cell can be stimulated by a small increase in the background concentration of Potassium ions in the extra-cellular fluid.  Quantitatively doubling the background concentration of potassium, 5mM, to just 10mM can effectively stimulate neural tissue. This increase translates to a Nernst potential of 18mV and an energy dissipation of approximately 600pW assuming a 1pL volume dispensed in 30 milliseconds. This is 5 orders of magnitude more efficient than an electrical interface, assuming 1 μA from a 10V supply.

The goal of this project is to create a 2-D array of electrically gated ion selective pumps for neural stimulation to restore vision in patients with retinal degenerative diseases. Such pumps could also sequester the potassium necessary for the devices functionality.