- Scientists at IIT Kharagpur, along with a team of researchers from South Korea, have devised a self-powered, piezoelectric nanogenerator that can harvest green energy from various mechanical and biomechanical motions.
What is Piezoelectricity?
- ‘Piezo’ meaning to press or to squeeze.
- Piezoelectric property essentially is based on the interplay between mechanical and electrical features of a material.
- Bonds that keep materials together are electrons and these electrons are the basis for electricity.
- Therefore there exists a connection between material mechanics and material electronics. Changing one will impact the other.
- Piezoelectricity is the generation of electric charges in certain solid materials in response to applied mechanical stress — such as the body’s motion, wind and water flow, or sound vibration.
- With mechanical stress–electricity interactions, sensors can be made that catch mechanical vibrations and transform those to an electrical signal.
- Further piezoelectric effect is completely reversible, which means when stress is applied, electricity is generated and when electricity is applied, stress is generated.
- Materials that show these properties include Quartz, topaz, human and animal bone tissue, fibres, different proteins etc.
Spider-silk as a Piezoelectric Nano fibre
- There are many materials in nature which have piezoelectric properties.
- Spider silk is a fibre secreted by spiders.
- Spider silk is the strongest natually-occurring fiber known with tensile strength comparable to that of high-grade steel.
- The nanogenerator harvests electricity out of spider silk.
- When pressure is applied, it leads to changes in the molecular structure of the material, making it capable of harvesting mechanical/biomechanical energy into green electricity.
- The nanogenerator is prepared by spraying water on spider silk and wrapping it around the pacemaker.
- Every time the heart beats, it will create external pressure on the spider silk, making it generate energy.
- While the pacemaker will keep the heart ticking, the heartbeat will in turn keep the pacemaker going.
- This makes spider-silk a self-powered, piezoelectric nanogenerator that can harvest green energy from various mechanical and biomechanical motions.
Why spider-silk in pacemaker?
- There are various ceramic or metal-oxide-based piezoelectric materials.
- But due to their brittleness and toxic nature, these materials have limitations for application inside the human body.
- Spider silk, however, is both biocompatible and biodegradable and is therefore perfect for being used inside the body.
Potential uses of Spider-silk nanofibres
- The spider-silk-based flexible nanogenerator is extremely sensitive to even minute pressure generated from body motions.
- This includes even the very small pressure arising from arterial pulse (signals arising out of small strains), throat movement during coughing, speaking, and drinking.
- This shows its potentiality in healthcare-monitoring applications.
- Its sensitiveness could also be used to monitor robotic applications.
- It can also for harvesting green energy and even for large-scale industrial applications.
- Devices made of these materials have the added advantage of size.
- Therefore it can externally be used for small electronic devices such as mobile phones, watches and calculators etc.