Researchers at IIT Kharagpur and Pohang University of Science and Technology (Postech), South Korea, have fabricated biodegradable and biocompatible self-powered energy harvesters (nanogenerators) from onion skin waste for a range of biomedical applications.
Nanogenerators convert kinetic energy created from vibrational and mechanical sources into electrical power, doing away with the requirement of external circuits or batteries. The fabricated nanogenerator is capable of harvesting several types of mechanical energies, including body movements, wind flow and even machine vibrations.
Technically such devices are called bio-piezoelectric nanogenerators (BPNG).
A single onion skin-based device can light up 30 green LEDs by repeated human finger touch response.When six such onion skin nanogenerator units are used in series, a maximum output voltage of 106 Volt can be obtained, which instantaneously turns on “more than 70 combined LEDs” (red, green and blue), making the device highly suitable in rural areas, the researcher informed.
The electricity in the cellulose-based onion skin peels is produced as a result of structural changes in the cellulose under external mechanical stress/force including movements as delicate as a finger touch.
Interestingly, the device is also capable of differentiating voice.
“The attachment of the nanogenerator to the throat can produce voltage signal during speech, the amplitude of which will depend on the intensity of throat vibration, making it suitable for voice/speech recognition.