Trees have a circulatory system that sends water from the roots to the leaves, and sends sugars from the leaves to the roots. There are two conduit like tissues that allow the trees to do this, called xylem and phloem.
Researchers took inspiration from the mechanism in trees, to create a chip that is able to pump water and sugars through channels passively, without the use of external pumps and without any moving parts. The chip can maintain circulation of the fluid for several days.
The passive pumping on the device, which the researchers have dubbed as a “tree-on-a-chip” can potentially be used as actuators for extremely small robots, or nanobots.
Anette “Peko” Hosoi, professor and associate department head for operations in MIT’s Department of Mechanical Engineering says “It’s easy to add another leaf or xylem channel in a tree. In small robotics, everything is hard, from manufacturing, to integration, to actuation. If we could make the building blocks that enable cheap complexity, that would be super exciting. I think these microfluidic pumps are a step in that direction.”
The water then goes through a semi-permeable membrane and down the phloem channels that contain sugars and other nutrients. In a process known as osmosis, there is more water flow if there is an increase in sugar content.
Researchers have tried to mimic the flow of water through the tree tissues before, but such flows tended to end in minutes. Water travels from the roots upwards to the leaves propelled by its own surface tension. The research has been published in Nature Plants.