How Robots Sense Through Optical Waveguides?

A team of researchers from the Cornel University recently developed flexible optical waveguides that permit the robots to get a feel of their surroundings by scaling external strain. The new innovation presents a strong alternative for the existing bulky and rigid tactile sensors that are embedded in regular robots. The solution was discovered in a soft prosthetic hand that is capable of demonstrating the final findings of this research team. An optical waveguide can be understood as a structure that directs visible light just like an optical fiber.

When a waveguide is derived from a stretchable material, the team working on this project was thus able to produce elastomeric optical waveguides that can deform with great ease. It is their deformation potential that permits the elastomeric waveguides usage as tactical sensors. To accomplish the task, the research team utilized a 4-step, soft lithography procedure that can generate the stretchable optical waveguides. These were given a lossy feature out of deliberation, this helped the waveguides in taking a desirable property. Resultantly, the more the waveguides deforms, higher is the amount of light that is lost to surroundings. With the help of a photodiode, the researchers were able to detect the amount of light that travel through waveguide. Since higher degree of deformation leads to lesser light, researchers were able to measure the amount of deformation over waveguides, this resultantly helped in sensation of external strain.

prosthetic hand that uses optical waveguides

Research team member, Robert Shepherd, says, “If no light was lost when we bend the prosthesis, we wouldn’t get any information about the state of the sensor. The amount of loss is dependent on how it’s bent.” For the prosthetic hand, the team had to combine multiple waveguides that were subjected to numerous tactile experiments. Under one trial, the hand was assigned with the task of recreating surfaces for seven different objects with loyal results. While, in another project, the hand was able to feel three different tomatoes and was able to tell which was most ripen.

Another member of team, Huichan Zhao, adds, “Most robots today have sensors on the outside of the body that detect things from the surface. Our sensors are integrated within the body, so they can actually detect forces being transmitted through the thickness of the robot, a lot like we and all organisms do when we feel pain, for example.”