Imagine if you can charge your smartphone via the T-shirt you are wearing without any electric shock. Scientists have found a way to generate electricity from nylon, raising hopes that the clothes on our backs will become an important source of energy.
These smart clothes will also monitor our health through miniaturised sensors and charge devices without any external power source.
This discovery — a collaboration between the University of Bath, the Max Planck Institute for Polymer Research in Germany and the University of Coimbra in Portugal — is based on breakthrough work on solution-processed ‘piezoelectric’ nylons led by professor Kamal Asadi from the Department of Physics at Bath and his student Saleem Anwar.
Piezoelectricity describes the phenomenon where mechanical energy is transformed into electric energy.
To put it simply, when you tap on or distort a piezoelectric material, it generates a charge.
Add a circuit and the charge can be taken away, stored in a capacitor for instance and then put to use — for example, to power your mobile phone.
While wearing piezoelectric clothing, such as a shirt, even a simple movement like swinging your arms would cause sufficient distortions in the shirt’s fibres to generate electricity.
“Piezoelectric materials make good candidates for energy harvesting from mechanical vibrations, such as body motion, but most of these materials are ceramic and contain lead, which is toxic and makes their integration in wearable electronics or clothes challenging,” Asadi explained in a paper published in the journal Advanced Functional Materials.
The challenge is to prepare nylon fibres that retain their piezoelectric properties.
The scientists discovered that by mixing the acid solution with the acetone (a chemical best known as a paint thinner or nail varnish remover), they were able to dissolve the nylon and then extract the acid efficiently, leaving the nylon film in a piezoelectric phase.
Developing piezoelectric fibres is a major step towards being able to produce electronic textiles with clear applications in the field of wearable electronics.
Most likely, the electricity harvested from the fibres of piezoelectric clothing would be stored in a battery nestled in a pocket.
This battery would then connect to a device either via a cable or wirelessly.
“In years to come, we could be using our T-shirts to power a device such as our mobile phone as we walk in the woods, or for monitoring our health,” said Asadi.