The sensitive robot fingers

The sensitive robot fingers

materialsworld:

A team of researchers from the University of Houston, US, has reported a breakthrough in stretchable electronics that can serve as an artificial skin, allowing a robotic hand to sense the difference between hot and cold water in a cup, while also offering advantages for a wide range of biomedical devices.

The work, reported in the journal Science Advances, describes a new mechanism for producing stretchable electronics, a process that relies upon readily available materials and could be scaled up for commercial production.

Cunjiang Yu, Bill D. Cook Assistant Professor of mechanical engineering and lead author for the paper, said the work is the first to create a semiconductor in a rubber composite format, designed to allow the electronic components to retain functionality even after the material is stretched by 50%.

The stretchable composite semiconductor was prepared by using a silicon-based polymer known as polydimethylsiloxane, or PDMS, and tiny nanowires to create a solution that hardened into a material which used the nanowires to transport electric current.

(A) Exploded schematic illustration of the strain sensor. (B) Photographs of the sensors under different levels of mechanical strain. © Measured electrical resistance of the strain sensor under different levels of mechanical strain along the channel length direction (black) and perpendicular to the channel length direction (blue). (D) Relative change of the resistance (ΔR/R_o) under cyclic stretching and releasing. (E) GF of the strain sensor with respect to the different strain. (F) Relative electrical resistance (R/R_o) change of the pressure sensor with respect to time under different levels of pressure. (G) Relative electrical resistance change of the pressure sensor under a loading (red) and unloading (blue) cycle. (H) Relative electrical resistance change of the temperature sensor with respect to the different temperature.

“Our strategy has advantages for simple fabrication, scalable manufacturing, high-density integration, large strain tolerance and low cost,” he said, adding that traditional semiconductors are brittle and using them in otherwise stretchable materials has required a complicated system of mechanical accommodations. That’s both more complex and less stable than the new discovery, as well as more expensive, he said.

The skin was also able to interpret computer signals sent to the hand and reproduce the signals as American sign language. “The robotic skin can translate the gesture to readable letters that a person like me can understand and read,” Yu said.

“We foresee that this strategy of enabling elastomeric semiconductors by percolating semiconductor nanofibrils into a rubber will advance the development of stretchable semiconductors, and … will move forward the advancement of stretchable electronics for a wide range of applications, such as artificial skins, biomedical implants and surgical gloves,” they wrote.