S. Himmelstein | June 14, 2023
A soft, seed-shaped robotic system has been 4D-printed as a biodegradable tool for monitoring soil properties and other environmental applications. Much like the South African geranium seed, which inspired its design, the seed-robot changes shape in response to environmental humidity,
Under specific environmental conditions, these geranium seeds detach from the plant, change shape and move independently to explore and penetrate the soil as a means of increasing germination success. Researchers from Italy’s University di Trento and Istituto Italiano di Tecnologia sought to replicate this capability by examining different materials with characteristics adaptable to the desired application, including biodegradable polymers and those that absorb humidity and expand like cellulose nanocrystals.
The 4D-printed biodegradable soft robot changes shape in response to humidity. Source: Istituto Italiano di Tecnologia
The device was then produced by 4D printing — the process of using 3D printing to create objects that can change their shape or properties in response to environmental factors such as light and temperature.
The seed robot was then engineered by combining 3D printing and electrospinning techniques. The researchers used fused deposition modeling to print a substrate layer comprised of the biodegradable thermoplastic polyester polycaprolactone that was activated with oxygen plasma to boost its hydrophilic properties. Electrospun hygroscopic fibers composed of a polyethylene oxide shell and a cellulose nanocrystal core were then added to the substrate.
The wireless, battery-free robot described in Advanced Science was demonstrated to transform itself and explore the environment autonomously and may find applications in various fields from environmental data collection to reforestation.
