A 3D-Printed Magnetic Focus Actuator for Laser Scanning Capsule Endoscopy

We report the design, manufacturing, and characterization results of a magnetic focus actuator and integrated circuit driver for use with miniaturized laser scanning capsule endoscopy. The capsule structure comprises: (1) a magnet-attached, SLA-printed focus actuator, (2) a lens and its housing, (3) a laser diode inserted into the electro coil, and (4) an actuator driver IC, which provides alternating current output at 32 Hz by down-converting the crystal frequency multiple times to match the mechanical resonance of the actuator itself. Due to the restricted power provided by the battery within the capsule, the IC is designed to mitigate higher harmonics for improved energy efficiency. Focus actuation tests were conducted following the assembly of the actuator and IC within the capsule, showcasing a total focal shift of 3.22 mm due to the interaction between the electro coil and Nd magnets.