Another Piezo-Textile Story!
A few weeks ago we brought you a story about a type of textile that could harvest the wearer’s motions to produce electricity. There we talked about piezoelectricity and how it utilized the wearer’s motions to generate electricity. What we got here is some news about an improvement to this pioneering technology, spearheaded by a group of engineers from the University of California, Berkeley.
So what do we have here?
Energy harvesting nanofibers that can be used to weave clothing and textiles!
These nanofibers can be called nano-sized generators and they possess the property of piezoelectricity. This is certainly not a new concept and we have dealt with it before. In a nutshell what happens here is that the nanofiber material harnesses the energy created through mechanical stress, stretches and twists and converts this into electricity!
Fiber nanogenerator on a plastic substrate (Image credit: Chieh Chang, UC Berkeley)
What’s unique about these nanofibers is that…
They are made from organic polyvinylidene fluoride (PVDF), which is flexible, cheap and easy to manufacture!
Structure of Polyvinylidene fluorid
So what’s the improvement that we mentioned before?
In our previous piezo-textile article the nanowires were made of Zinc Oxide
In that previous article we talked about ‘nanogenerators’ that were made out of an inorganic semiconducting material; zinc oxide. These are more fragile and harder to grow in significant quantities unlike the organic PVDF material used here.
These ‘nanogenerators’ are tiny!
Just how tiny? They have diameters that only amount to 500 nanometers, which is 100 times thinner than a human hair and one-tenth the width of common cloth fibers!
What about the output?
The generated electrical output in these experiments ranged from 5 to 30 millivolts and 0.5 to 3 nanoamps.
Additionally these nanofibers were subjected to 100 minutes of stretching and releasing at a frequency of 0.5 hertz and this resulted in no noticeable degradation of the material!
The energy conversion efficiency…
Of this process was as high as 21.8 percent, with an average of 12.5 percent.
Doesn’t sound too impressive? Well… compare that with the 0.5 percent to 4 percent obtained with typical power generators made from experimental piezoelectric PVDF thin films or the 6.8 percent achieved with nanofibers made from inorganic zinc oxide!
So that 21.8 percent is not too shabby anymore don’t you think?
via: University of California, Berkeley
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