A small device can harvest energy from the breeze generated as you walk and could potentially be used to power your gadgets.
The apparatus, developed by Ya Yang at the Chinese Academy of Sciences in Beijing and his colleagues, takes advantage of the triboelectric effect. This occurs when certain materials become electrically charged as they rub together. The researchers used an 8-centimetre-long tube containing two thin films, each made up of a layer of plastic on top of a layer of silver that acts as an electrode.
The two films flutter in response to even a slight breeze 鈥� a wind speed as low as 1.6 metres per second. As they brush against each other they generate an electric current, which is then transmitted through the silver electrodes to drive a tiny generator in the device.
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In one test, Yang and his team put the device on a volunteer鈥檚 arm and found that the airflow generated by the person swinging their arm as they walked was enough to generate power.
The wind speed required for most wind turbines to generate power is 3 metres per second, says Zhenzhong Zeng at Southern University of Science and Technology in Shenzhen, China. 鈥淎ny wind with speed lower than that is wasted,鈥� says Zeng. This device would let us make use of lighter breezes, which have the potential to power small electronic devices, he says.
The device can produce 2.5 milliwatts of power, enough for 100 tiny LED lights, a thermometer or a pressure sensor. It has a wind-to-energy conversion efficiency of 3.23 per cent, which is much lower than the average wind turbine, but higher than previously reported for wind scavenging devices, say the team.
鈥淪uch wind energy harvesters can be used to power wireless sensors deployed in open space where breezes are available,鈥� says Dibin Zhu at the University of Exeter, UK. Another application could be to power wireless sensors put inside heating, ventilation and air conditioning ducts for air quality monitoring, he says.
Cell Reports Physical Science
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