Bio-waste onion skin as innovative nature-driven piezoelectric material with high energy conversion efficiency

 Environmental pollution today has become one of the global challenges that need to be addressed urgently. The burning of fossil fuels is the highest pollutant, and thus it is recommended to use and develop green and renewable sources of energy. Although there are various sources of green energy such as the solar energy, piezoelectric generators have become more useful. They have added advantages over its counterparts like triboelectric nanogenerators due to its high durability, high performance, and high sensitivity. For biomedical purposes, the material used for fabrication of these piezoelectric nanogenerators should be biodegradable, non-toxic and biocompatible. Collagen fibrils have been found to be one of the materials that can be used in the fabrication of biomedical piezoelectric nanogenerators. They are both biocompatible and biodegradable and are found naturally from tissues of mammals. This work, however, focuses on utilizing bio-compatible and biodegradable onion skins from waste products and garbage as a piezoelectric material. It is readily available, inexpensive and does not require chemical treatment.

Researchers at Pohang University of Science and Technology in South Korea: Dr. Sandip Maiti, Juhyun Lee, Dr. Avnish Kumar Mishra, and Professor Jin Kon Kim in collaboration with Sumanta Kumar Karan and Professor Bhanu Bhusan Khatua from the Indian Institute of Technology Kharagpur, India developed a bio-piezoelectric nanogenerator with waste onion skin as the piezoelectric material. The technology is preferred over others due to its efficiency and effectiveness. The work has been published in the Nano Energy journal.

The research team used onion skins from garbage as a piezoelectric material for the generation of renewable energy from biomechanical activities. Onion skin bio-piezoelectric nanogenerators (OSBPNG) is ultrasensitive towards throat movements such as drinking, swallowing, and coughing. Because it is also very sensitive to minute pressures originated from heart or pulse, it could be effective in various in-vivo biomedical diagnoses and e-healthcare monitoring.

The results obtained demonstrated the effectiveness and efficiency of the material. For instance, it performed better regarding output voltage, piezoelectric strength, and current. However, the paraments mentioned above depended on the number of units used. Six units in series, for example, produced up to 106 volts.

The study is the first to use of onion skin as a piezoelectric material and will help in advancing the area as it is more convenient compare to other materials. Also, plant materials are much more usefulness than living creatures in both handling and supply. Onion skin is readily available as waste products. Their significant advantage is that they are inexpensive, biodegradable, biocompatible and do not require chemical treatment.

 OSBPNGs have high power density. The current and output voltage produced depends on the units used. The more units, the more voltage/current produced. The units work better when arranged in series or parallel. This means that it can be used for large-scale production. OSBPNG can be a useful tool in harvesting energy from the human body movement and activities. It does not matter whether the body is at rest or work. The device is also sensitive to body movements and signals including heartbeat, throat movement, eating, coughing and running among others.

With the high demand of smart electronics devices in the industrial applications today, the use of onion skin is expected to increase tremendously. This is because OSBPNG is self-powered devices that can be used for both the small-scale and large-scale applications. The material is environmentally friendly as it can be recycled from the available bio-waste products. With such devices, the future is promising.