Temperature-sensitive technology for artificial skins: smart structures

Researchers around the world are in the midst of developing artificial skins essential to modern robotics, prosthetic limbs, and other applications. Designed to emulate the most practical properties of human skin, some artificial skin technologies have managed to surpass the sensory capabilities of living tissues. One such technology is a temperature-sensitive electronic film, which has paralleled the record performance of the world's most sensitive heat-detecting organism, the Crotalinae, commonly know as the pit viper.

While in the process of fabricating materials for synthetic wood, a team of researchers discovered a film made of pectin, a sugar molecule responsible for the temperature sensitivity in plants, could exhibit an electrical response to changes in temperature when enriched with positively-charged calcium ions. This finding led to the study "Biomimetic temperature-sensing layer for artificial skins" by senior author Chiara Daraio, et al., which was published in the February issue of Science Robotics. The transparent and flexible pectin films under examination were incorporated into artificial skins made from elastic materials such as silicon rubber, then tested for sensitivity.

Flexible pectin film
Photo: Caltech/Science Robotics

Daraio shared her team's research in a plenary presentation titled "Plant nanobionic materials for thermally active, soft, artificial skins" at SPIE Smart Structures/NDE in Portland, Oregon, 26 March.

Bionic materials are a class of materials that aims to preserve, enhance, and exploit properties of living systems for engineering purposes, notes Daraio. In most cases, however, creating synthetic materials that reproduce or surpass the performance of natural materials has been elusive. We fabricate synthetic materials that combine carbon nanoparticles in a matrix of plant cells, to create new temperature sensors with record-breaking responsivity. We extract the active molecule, pectin, responsible for the temperature sensitivity in plants, to create ultra-sensitive, flexible membranes that can map temperature changes from a distance. These materials augment properties of synthetic skins for robotics and prosthesis, and can find applications in consumer electronics or NDE.

See news + photos from SPIE Smart Structures/NDE.