Indian Scientists Develop Soft Robotic Actuators From Waste Onion Peels

The team of scientists also found that an additional ultra-thin layer of gold can increase the magnitude of these robotic actuators by more than two times, and bi-directional photo-controlled face-sensitive movement can be enhanced.

Indian scientists have developed soft robotic actuators using porous carbon nanoparticles from onion peels which were thought good for nothing but waste. The team is led by Professor S. Krishna Prasad at the Centre for Nano and Soft Matter Sciences (CeNS) in Bengaluru.

"The actuators can act as efficient traps for the illuminating low-power near-infrared (NIR) light and can convert a control signal into mechanical motion with bioengineering applications such as drug delivery, wearable and assistive devices, prostheses, and even artificial organs," India's Ministry of Science and Technology said in a statement on Tuesday.

These "soft robots" consist of rubber-like polymers with embedded nanomaterials that can convert a source of energy into mechanical motion. The usage of these actuators are gaining popularity and they can be used as targeted applications in areas including bio-medical, military, and remote space operations. Additionally, these actuators have a high thermal conductivity that helps in the rapid distribution of the heat generated locally by thermal and photo-thermal stimuli.

Professor Prasad realised the possibility of using porous carbon nanoparticles (PCNs) with these actuators and surprisingly, the PCNs were prepared from waste onion peels by Dr Gurumurthy Hegde at the B.M.S. College of Engineering in Bengaluru.

"Exhaustive measurements showed that the photothermal conversion efficiency and the heat-trapping capability is seen to be strongly correlated with the pyrolysis temperature employed for PCN preparation, and thus is an effective control parameter," Pragnya Satapathy, a senior research fellow, said.

According to the researchers, these actuators were efficient traps for illuminating low-power near-infrared (NIR) light "which resulted in the film comprising PCNs and PDMS achieving large magnitude (multi-mm) actuation with fast (less than a second) responses."