Scientists extracted the electric power from an internal ear

Scientists could use for the first time a natural potential difference in an internal ear of mammals — biological “the electric battery” — for a food of a tiny radio transmitter that opens great opportunities for creation of non-volatile implants for the person.




















Implanted devices demand rather large amount of energy. Patients should or be reconciled with need of repeated operations for replacement of power supplies, or to use bulky wireless power sources. “Local” power sources, such as or movement of muscles it is impossible to use heat of a body without external thermo – or piezoelectric devices.

Patrick Mercier from Massachusetts Institute of Technology and its colleague decided to use a natural source of a current in one of bodies of an internal ear of mammals — in a snail.






















This body represents filled with liquid and the tube curtailed into a spiral and is responsible for perception of sounds. Inside the tube is divided by a membrane, from one its party is Perilymph with high concentration of ions of sodium, and with another — endolymph with the big maintenance of ions of potassium. Between them the potential difference from 70 to the 100th millivolt which Mercier’s group decided to use is created.












Scientists carried out a series of experiments on guinea pigs (Cavia porcellus) — at these rodents the anatomy and physiology of an ear is similar to the human. Measurements showed that the snail of guinea pigs generates a current from 14 to the 28th microampere with tension from 30 to the 55th millivolt. The capacity of this “battery” received on an exit taking into account resistance of electrodes and other restrictions made from 1,1 to 6,3 nanowatt.

Such low current and capacity put two problems before researchers. The first of them was that electronics on the basis of transistors demands for work tension at least in hundreds millivolt. The second consisted what even the most power effective electronic schemes demand capacity in hundreds times more.

Scientists solved a problem, having created the special scheme which was started in work from the outside of, by means of a wireless microwave radiator of energy (working by the same principle, as wireless input readers for contactless cards in subway turnstiles). The aerial on a chip accepted energy, the scheme started to work, consuming capacity in hundreds times smaller, than schemes existing still.

During experiment the microchip in the size 9 on 11 millimeters worked on an “ear” electricity of a rodent within five hours, transferring on frequency 2,4 gigahertzes data on tension in a snail. Researchers didn’t begin to implant the chip, but they note that the device quite could be located in a cavity of a middle ear of a guinea pig. Besides, authors of article checked, how electrodes affected hearing — as it appeared, the hearing at rodents went down only in the field of about 23 kilohertzes.