Researchers have built a microscope-scale system that moves flexible objects with water currents instead of a probe. The FlowBot platform adjusts currents at the water surface, where a floating target can move while staying in the microscope's plane of focus.
That combination addresses a difficulty in handling small, soft objects: a rigid tool can deform them or push them out of view. FlowBot uses computer-controlled pumps to inject and drain water through ports around a chamber. Changing the direction and strength of the flow can move or rotate an object without direct contact.
Choosing the pump commands is harder because the resulting current changes across the chamber and over time. The researchers' FlowNet model learns this relationship from simulated flow fields, which describe the water's speed and direction at many locations. It predicts how a flow develops and can work in reverse to infer an input for a requested flow pattern.
The experiments tested programmed paths with several flexible targets. In one demonstration, the team steered duckweed along paths spelling “SJTU”. Simple segments followed the plan closely, but the reversal in the “T” produced a loop: the object's irregular shape and local flow introduced forces that the model did not capture.
A separate arrangement used four angled nozzles to keep duckweed moving in an elliptical orbit. Together, the demonstrations show that controlled surface currents can produce useful motion patterns. They do not establish how accurately the system could continually correct an arbitrary object's position, because the reported path-following tests used open-loop commands rather than continuous position feedback.