Energy extraction from the biologic battery in the inner ear

Abstract

Endocochlear potential (EP) is a battery-like electrochemical gradient found in and actively maintained by the inner ear1,2. Here we demonstrate that the mammalian EP can be used as a power source for electronic devices. We achieved this by designing an anatomically sized, ultra-low quiescent-power energy harvester chip integrated with a wireless sensor capable of monitoring the EP itself. Although other forms of in vivo energy harvesting have been described in lower organisms3-5, and thermoelectric6, piezoelectric7 and biofuel8,9 devices are promising for mammalian applications, there have been few, if any, in vivo demonstrations in the vicinity of the ear, eye and brain. In this work, the chip extracted a minimum of 1.12 nW from the EP of a guinea pig for up to 5 h, enabling a 2.4 GHz radio to transmit measurement of the EP every 40–360 s. With future optimization of electrode design, we envision using the biologic battery in the inner ear to power chemical and molecular sensors, or drug-delivery actuators for diagnosis and therapy of hearing loss and other disorders.

Advances in Microelectronics for Implantable Medical Devices

“…On the subject of providing power to implantable medical devices, it is expected that systems using energy harvested from outside and inside the human body will evolve. An example of such a system that uses the cochlear in the inner ear as a battery source to supply a 2.4 GHz radio transmitter is described in [107]. For such systems ultra-low power circuits are essential.…”

Future of Implantable Devices for Cardiac Rhythm Management

“…Future improvements in sensor technology include the miniaturization of sensors with biocompatibility and possible biologic energy-capturing technology to minimize dependence on battery. 70 Aside from technical issues, widespread use of implantable intracardiac and blood pressure monitoring still awaits demonstration of clinical benefit and an indication that medical input to pressure data can be kept to a minimum.…”

A Contemporary Survey on Energy Harvesting Techniques for Next Generation Implantable Bio-Medical Devices

“…If the potential is large enough and the corresponding power condition circuits can be designed to match with the requirement, electrical energy can be harvested directly from this potential. In [15] it has been shown that nW of power can be extracted from the ear of a guinea pig for up to 5 hours. For out-of-body power delivery, external energy source is used to couple the energy into the IMDs or directly activate the energy harvester implanted inside the body.…”