FIG. 1.

Localization and closed-loop motion control of a helical robot with a diameter of 1 mm are utilized in clearing blood clots in vitro. (a) The long and short saphenous veins (superficial veins) of the leg are commonly affected by thrombosis. (b) An array of Hall-effect sensors can be mounted along a superficial vein and used to localize a helical robot. The helical robot is actuated using two rotating dipole fields and closed-loop control is achieved based on its estimated position.