The Nanotechnology Series (Part 2 of 4): Turning Cars, Waves, and People into Power with Nanogenerators




This article is the second in a four-part series that explores the Internet of Nano Things (IoNT) and the growing field of IoNT research and applications. Read part one here.

The Internet of Things (IoT) devices combine many technologies – such as wireless communication, software, sensors, and of course, some sort of electric power.

The majority of IoT applications on the market today are powered by batteries or power cables. But with the Internet of Nano Things (IoNT) that power could be sourced by the vibration of a car engine, an ocean wave, or even simple human movement.

Believe it or not, this kind of power will be commercially available in the near future -- thanks to Dr. Zhong Lin Wang. Dr. Wang is a Hightower Chair in Materials Science and Engineering and a Regents’ Professor at Georgia Institute of Technology. Dr. Wang is a pioneer and world leader in nanoscience and nanotechnology, which is the construction and use of atomic- or molecular-scale functional structures which have at least one characteristic dimension measured in nanometers. As a reference point, a human hair is typically 50 micrometers wide, while one nanometer is one 80,000th of a hair width.

A key focus of Dr. Wang’s research in this area, which began in 2005, is self-powering nanotechnology devices that harvest energy from their environment – whether it’s a car, a human, or a vast body of water.

To capture live mechanical energy such as vibration, sonic waves, wind, hydraulic, or human movements, Dr. Wang and his researchers have invented the nanogenerator – which can be as small as a few millimeters. His work in this field has inspired a worldwide effort in academia and industry in the study of energy for micro-nano systems.

“Nano devices have wide application possibilities and can be used in every corner of life,” said Dr. Wang. “They can be adapted to any kind of electronic system which has moving objects that could be used as a self-sustaining power source.”

A particularly promising application area is medical devices, where wireless nanodevices and nanosystems can be used in-situ for real-time, implantable biosensors. For instance, Dr. Wang and his team successfully developed an implantable triboelectric nanogenerator (iTENG) for biomechanical energy harvesting in a living adult animal.

In its simplest form, the iTENG uses two sheets of dissimilar materials – an electron donor and an electron acceptor. When these two materials are in contact, electrons flow from one to the other. If the sheets are then separated, one sheet holds an electrical charge, which is isolated by the gap between them. If an electrical load is then connected to two electrodes placed at the outer edges of the two surfaces, a small current will flow to equalize the charges.

Dr. Wang and his team implanted the iTENG in the heart of a swine. The device used the animal’s heartbeat to power the monitoring of physiological cardiac data transmitted from its heart for a continuous period of over 72 hours. The iTENG not only powered the monitor, but it also powered the process signals from the heart and transmitted data.

Because it is an in vivo (within a living organism) device, it is constructed using an encapsulation strategy with biocompatible materials that include polytetrafluoroethylene, polydimethylsiloxane, and Parylene film. Hence, the device is strong, leak-proof, and erosion-free, while still having a high degree of flexibility and sensitivity. Once these devices have Food and Drug and Administration (FDA) approval and are available for commercial use, they hold great promise for self-powered wireless healthcare monitoring.

Another area of exploration in Dr. Wang’s labs is turning people into self-powered systems. His team has developed power management systems for fitness bands and smart watches that harvest energy from human motions, such as running, walking, or tapping fingers.

The researchers are also experimenting with harnessing energy through fabric for people on the move, such as soldiers, hikers, and others that could benefit from a “power” shirt or jacket. They have developed the first microfiber-nanowire hybrid nanogenerator which uses textile fibers to convert mechanical movements, such as body motions, muscle contractions, or blood pressure, into energy. “Imagine hats powered by solar energy, or shoes powered by walking,” said Dr. Wang. “That could help track the position of lost young children, or older people with dementia.”

Dr. Wang believes that self-powering systems are key to the future of IoNT, as the technology will create new innovative ways of using sensors, especially where there is a need for a particularly small device. As to their commercial availability, Dr. Wang believes they are close. “Nanogenerators may be available for non-medical markets within the next couple of years,” he said. “Medical devices that require FDA approval will most likely take longer, with availability in about five years or so.”

Don’t forget to check back to learn more about the IoNT in the coming weeks.