Most of the currently operating robotic limbs that mimic the human hand are very cumbersome and almost insensitive. A group of researchers at Cornell University, led by the assistant professor of the Department of Mechanical and Aerospace Engineering, Robert Shepard, was able to endow the soft robot with the ability to feel objects, like humans.
For this, flexible optical waveguides were integrated into the soft prosthetic arm. They were first used in the early 1970s when they were used in devices for tactile and acoustic sensing. Almost 50 years later, the process of their manufacture has been significantly improved, including using 3D printing , resulting in the development of elastomeric sensors, which have found application in soft robotics.
Scientists have developed a process of soft lithography to produce a rod through which light propagates and the outer surface of the waveguide, which also contains an LED indicator and a photodiode.
The more the prosthesis of the hand deforms – and this happens at the moment of contact with an object – the less light passes through the rod. Reduction of the intensity of light is fixed by the photodiode, as a result of which the prosthesis “evaluates” the objects surrounding it. In the absence of an object, the light is not lost and the sensors simply “remain silent”.
According to Robert Shepard, future soft robots equipped with optical waveguides will significantly increase their sensory capabilities.