Inspiration from Plant Roots: a Robotic Root Apex for Soil Exploration

In an attempt to compensate for their sessile nature, plants have developed growth responses to deal with the copious and rapid changes in their environment. The process by which plant roots expand in soil involves water uptake through osmosis and imbibition, and an overall increase in size by cell division. Each root apex has sensors to get information from the environment, which is then transduced, processed, and used to direct the growth towards regions of the soil with the best minerals and water availability. This knowledge has inspired a novel concept of robotic system, leading to the design of a robotic root apex, able to steer and host sensors. The robotic root apex consists of a cylindrical main body, with a diameter of 22 mm, ending in a bulletshaped tip, with a total length of 60 mm. The robotic root body hosts an actuator based on an osmotic principle. It is composed of three equal-size chambers, containing the fluids for the osmotic actuation. The tip integrates gravity and humidity sensors, together with the electronics for sensory data acquisition and steering control. First prototypes of the robotic apex have been fabricated by a 3D printer InVision si2, with a plastic material.