Can we use material intelligence to power a robot?

Plants use an innate material intelligence to drive movement. Their scales open and close elastically due to hygroscopic expansion differences in their cell layers. This allows for repeatable motion without the use of active energy, a subject of increasing interest as pressure grows to move away from energy-intensive electromechanical systems, prone to failure over time. Several hygroscopically-activated bimaterial actuators have been developed using the logic of pinecones, however few systems have been devised to act as autonomously moving organisms. As such, we present a self-propelling, autonomous, and programmable robot, capable of flexible locomotion through the local introduction and removal of moisture.

Work by Raphael Kay, Kevin Nitiema, with external guidance from David Correa (Waterloo).

The robot’s locomotion follows a four-step cycle. The first step involves depositing moisture to the front legs in an otherwise low moisture environment. The second step involves depositing moisture to the back legs in an otherwise low moisture environment. The third step involves removing moisture from the back legs in an otherwise low moisture environment. The fourth step is passive, allowing the robot to return to its rest state.

A displacement of 43 cm was observed in 127 minutes.