Italian researchers have designed a soft robot that mimics the tendrils of a plant and has a movement system inspired by osmosis.
Osmosis allows plants to transport water internally by relying on the variation of solute concentrations either side of semi-permeable membranes. Water travels across the membrane to equalise the concentration on both sides. Scaled up from the cellular level, the process controls hydraulic plant movement such as tendrils curling or climbing.
Developed at the Istituto Italiano di Tecnologia (IIT) in Genoa, the robot is made of a flexible PET tube containing a liquid with electrically charged particles. Using a 1.3 Volt battery, the ions are attracted and immobilised on the surface of flexible electrodes at the bottom of the tendril, and the corresponding movement of the water causes the robot to flex and curl. To reverse the motion, the power source is simply switched off. According to the researchers, this is the first time such a system has been implemented in a soft robot, and the breakthrough could influence everything from wearable technology to industrial robotics.
“Plant-inspired osmotic actuation was recently proposed, yet reversibility is still an open issue hampering its implementation, also in soft robotics,” states the research abstract, which appears in the journal Nature Communications.
“Here we show a reversible osmotic actuation strategy based on the electrosorption of ions on flexible porous carbon electrodes driven at low input voltages. We demonstrate reversible stiffening and actuation of a tendril-like soft robot (diameter ~1 mm). Our approach highlights the potential of plant-inspired technologies for developing soft robots based on biocompatible materials and safe voltages making them appealing for prospective applications.”
The research was led by IIT’s Barbara Mazzolai, who coordinated one of the first horticulturally-inspired robot projects, ‘Plantoid’, back in 2012. Based on the latest research, Mazzolai is now working on a new project called ‘Growbot’, which is aiming to develop a robot that can adapt its growth and movement in response to its environment.