Nanogenerator: Generating Electrical Energy from Breathing!!

From the time human race has invented electricity and started to develop innovative & advanced electrical & electronic products, there is a parallel field of research and development happening alongside which focuses on how to power these electrical and electronics products efficiently. We have produced Direct Current, followed by AC current for long distance transmission as DC is prone to more loses, we have come up with many portable, non-rechargeable/rechargeable batteries with various battery chemistries to power portable electronic gadgets, then we have made power systems that harness energy from renewable sources (Sun, Wind etc.)

The underline fact is that over the period of time we have tried to make power (electrical) more economical, efficient and less depended on nature's non renewable sources. One such innovative power source is Nanogenerator. Nanogenerator was first proposed by Dr. Zhong Lin Wang at Georgia Institute of Technology in 2006. It produces electrical power from the energy available in the environment. In other words Nanogenerator is a self powered system as energy available in the environment is in abundance and is available for free of cost. We just need to figure out a way to convert this energy into a useful electrical energy. This is an underline principle of Nanogenerator.

Principle of Nano Generator

Nanogenerator is a small semiconductor Integrated Circuits (ICs) etched on a elastic substrate to make it flexible. This IC converts mechanical and thermal energy produced by physical reactions into electricity. Mechanical and thermal energy can be present in the form of noises, vibrations, light wind, body movement, muscles stretching, blood flow in the body, breathing etc. When we walk we generate 67Watts of mechanical energy, our finger movement generate 0.1W of power. Chemical reaction taking place in our body to release energy from food we eat and constitute blood flow, breathing etc could be used to generate electrical power. Table below shows the mechanical energy that our body generates from various physical activities and corresponding theoretical electrical energy that it could transform in.

Nanogenerator semiconductor ICs consists of array of 'nanowires' that are made up of piezoelectric zinc oxide material. Piezoelectric material has a property that it produces potential difference when they are strained. The straining force that are caused by the physical activities discussed above cause the transient flow of electrons in the external circuit and constitute current. These nano wires can be triggered by a tiny external force that too at wide range of excitation frequencies (1Hz to 1000 of Hz). By combining the effects of thousands of such piezoelectric nanowires, a gentle strain can produce about 1.2V of electricity which can power an LED and a small LCD unit. Those days are not very far when your mobile phone will charge while in your pocket as nano generators on your body will do the job for you. Similarly you may not require batteries for your TV remote because when you pick the remote it will come to life because of naongenerators on your body! Advantages of nanogenerators are that they produce electricity continuously and simultaneously. More, importantly they could be interfaced with our biological system.

By Amit Monga - Asst. Prof., ECE Chitkara University Himachal Pradesh &
Sagar Juneja, Research Associate Chitkara University

References:

1.https://en.wikipedia.org/wiki/Nanogenerator

2.http://www.engineersgarage.com/articles/nano-generators-pocket-powerhouses