The power of your ear

For the first time, scientists have managed to connect a medical implant and feed it with the energy of a natural battery that we all carry in our inner ear. Yes, all mammals have in their inner ear an "endocochlear potential" similar to a battery. It is located in a chamber filled with ions that, with the aid of sound waves, produce electricity gradients which become auditory nerve signals processed by the brain. In words of the discovers at MIT: 

"The ear converts a mechanical force — the vibration of the eardrum — into an electrochemical signal that can be processed by the brain; the biological battery is the source of that signal’s current. Located in the part of the ear called the cochlea, the battery chamber is divided by a membrane, some of whose cells are specialized to pump ions. An imbalance of potassium and sodium ions on opposite sides of the membrane, together with the particular arrangement of the pumps, creates an electrical voltage." 

"We have known for 60 years that this battery exists and that it’s really important for normal hearing, but nobody has attempted to use this battery to power useful electronics." says Konstantina Stankovic, a researcher at Harvard-MIT Division of Health Sciencies and Technology. 

So far, they have managed to use this source of electricity to power a tiny device without affect hearing.

Image: Patrick P. Mercier - MIT website

This technique could be used to power small ear implants which assist people with hearing loss, to deliver drugs to the body or to feed other sensors. At present, the voltage and power are so weak that scientists had to design a mini converter circuit so the electricity could be exploited by a small electronic device (see the image for a close view into the device size).

http://web.mit.edu/newsoffice/2012/biological-battery-1107.html

A pharmacy inside the body

The results of tests conducted by researchers at the Massachusetts Institute of Technology (MIT) and the company MicroCHIPS in a group of women with osteoporosis opens the door to the widespread use of remote administration of drugs. This was achieved by inserting a microchip under the skin which is capable of administering a medicine, thus allowing the patient to avoid daily injections of drugs.

And can’t patches do that already? Well, there are two main differences: the microchip allows remote control of drug release and also it can be used to administer more than one drug. The chip acts like a pharmacy inside the human body, a technology that can be used to treat from cancer to multiple sclerosis. Thinking further, I also envisaged the possibility of using the chip to administer vaccines automatically at the different stages of human development. And all this in a device with the size of a small pen drive!

And how does it work? The chip contains a daily dose of medication in small wells that are covered by a thin layer of gold nanoparticles which protects and prevents the drug from coming out.  The chip can be programmed to administer the medication according to a programmed schedule or commands sent wirelessly through a special frequency. These commands cause the gold to dissolve and allow the drug entering the bloodstream.

For testing, a group of seven women aged between 65 and 70 had the chip implanted through a simple procedure performed under local anesthesia. For four months the chip administered them an osteoporosis drug called teriparatide in doses comparable to those provided by injections, without any negative side effects.

“We hope this really is the dawn of a whole new way of thinking about delivering medications,” said co-author Robert Langer, a professor of cancer research at the Massachusetts Institute of Technology.  However, for he and his and colleagues, “the ‘hairpin’ road to the clinic might be long and winding, but a versatile implantable device that exploits the microchip approach for controlled drug delivery will be well worth the wait for patients with chronic diseases,”