December 8, 2023

Italian researchers have created a novel 4D printed biodegradable soft robot shaped like a seed that can change shape in response to changes in humidity and navigate soil. The device has great potential as a new way of environmental monitoring.

4D printing is 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 technique has previously been used to create self-assembling, programmable material technologies.

Now, 4D technology is being used to create soft robots that can analyze soil. Drawing inspiration from the seed structure of the South African geranium (geranium), which change shape according to the humidity of the environment, researchers at the Istituto Italiano di Tecnologia in Genoa have created the first biomimetic, biodegradable seed robot.

“Our research begins with observations of nature and aims to mimic the strategies of organisms, or their structures, and replicate them in robotics with less environmental impact in terms of energy and pollution,” said the study’s corresponding author Barba said Barbara Mazzolai. .

The seeds of flowering plants in the Pelargonium family, including geraniums, exploit their hygroscopic (humidity-activated) properties by detaching themselves under appropriate environmental conditions. Once separated, they change shape and penetrate the soil independently, increasing the chances of germination.

After thoroughly studying the structure and biomechanics of natural seeds, the researchers replicated them using a combination of 3D printing and electrospinning. Electrospinning is a fiber production method that uses electricity to pull charged polymers to the diameter of the fiber, on the order of hundreds of nanometers.

The researchers used fused deposition modeling (FDM) to print substrate layers composed of polycaprolactone (PCL), a biodegradable thermoplastic polyester that was activated using an oxygen plasma to make it more water-absorbent (hydrophilic) . They then added electrospun absorbent fibers consisting of polyethylene oxide shells and cellulose nanocrystal cores to the substrate.

In tests, the soft robot explored soil samples, adjusting its shape to interact with its roughness and cracks. It is so energy efficient that it can lift around 100 times its own weight.

The video below, produced by the Istituto Italiano di Tecnologia, shows how the robotic seeds reacted to the soil during testing.

(embed) (/embed)

The first biodegradable seed robot that changes shape in response to humidity

The novel device offers a new way to monitor Earth unobtrusively, the researchers say.

“With this latest study, we are further demonstrating that innovative solutions can be created that not only monitor the well-being of our planet, but do so without altering it,” Mazzolai said.

The researchers hope the device’s low cost, simple design and data collection capabilities will be especially useful in remote areas.

“These biodegradable and energy-autonomous robots will be used as wireless, battery-free tools for surface soil exploration and monitoring,” said Luca Cecchini, lead author of the study. “This bio-inspired approach allowed us to create low-cost instruments that can be used to collect field data with high spatial and temporal resolution, especially in remote areas where no monitoring data is available.”

The study was published in the journal advanced science.

source: Italian Institute of Technology