A Resonant Pulley Rotary Actuator for Scanning Capsule Endoscopy

We present a compact electromagnetically actuated 3D-printed rotary actuator for use in Scanning Capsule Endoscopy. The actuator comprises two cantilevers connected to a rotating body via nylon strings. External coils and the magnets placed on the cantilevers create an electromagnetic force with which the rotation can be initiated. Opposite coils are driven out-of-phase to enable resonant actuation. An electrical circuit model and finite element simulation results of the fundamental mode frequency are provided for the designed device. The design is manufactured via fused deposition modeling using polylactic acid (PLA) and thermoplastic polyurethane (TPU). Experimental results reveal a 98 ° total scan angle at 21 Hz resonance for the TPU actuator and a 19.7 ° total scan angle at 237 Hz resonance for the PLA actuator. Overall, the presented rotary actuator compares favorably over i) micromotor counterparts in terms of form factor (having a diameter of 13 mm and a total height of 7 mm) and ii) MEMS counterparts in terms of total scan angle. Manufacturing cost and duration are yet other benefits of the presented device, owing to 3D printing technique. With further development, the presented device can serve within a disposable capsule endoscopy unit for clinical use.