self-powered flow-induction on the event horizon...,

neurologica |  Energy is what makes stuff happen. The ability to generate energy in useful amounts and locations is key to our civilization. Often when discussing energy we are focusing on big energy, how to make large amounts of energy in a cost-effective manner with minimal negative impact on our environment.

The ability to generate tiny amounts of energy is also useful, however. One particular application requiring a small but reliable source of energy is implantable devices, such as cardiac pacemakers. Right now pacemakers are run by small batteries. These batteries have a limited lifespan, and need to be surgically replaced.

What if, however, we could generate the required electrical energy from the body itself. Our bodies use a relative large amount of energy, creating movement, electrical signals, generating heat, assembling proteins and cells, and undergoing biochemical reactions. All we would need to do is tap into a tiny slice of this energy and there would be enough energy to power a pacemaker, or many other small implantable devices.

A recent paper discusses a successful demonstration of one such technology. Hwang et. al. report:

A flexible single crystalline PMN-PT piezoelectric energy harvester is demonstrated to achieve a self-powered artificial cardiac pacemaker. The energy harvesting device generates a short-circuit current of 0.223 mA and an open-circuit voltage of 8.2 V, which are enough to meet the standard for not only charging commercial batteries but also stimulating heart without an external power source.

The piezoelectric effect is a property of some materials that converts mechanical stress into electrical current. In the body, mechanical stress can derive from the beating of the heart, the movement of the chest wall in breathing, the movement of limbs, or the bouncing movement of walking. The idea of harvesting electricity from such movement through the piezoelectric effect has been around for a while, and it’s good to see a successful demonstration of this principle.

Other types of devices that could benefit from this technology include hearing aids, medication pumps, vagal nerve or deep-brain stimulators, and implantable sensors (such as blood glucose monitors).

The technology could also be used for wearable or portable electronic devices. Flexible piezoelectric devices could provide extra juice to your cell phone, extending the life of its charge, or even providing an emergency charge if you are away from an outlet.

It’s likely that the technology would also give a boost to the development of new wearable electronics applications. A major limitation of such technology is providing convenient power.