A 3D-printed spiral actuator for focus adjustment in circumferential scanning endomicroscopy

In this study, we showcase the design, manufacturing, and characterization of the focus adjustment actuator for use in capsule endoscopy. The actuator has a spiral flexure, carrying a lens and multiple magnets at its center to facilitate focusing through electromagnetic actuation. The interplay between the spiral flexure length and the lens size is investigated for optimal performance. An external coil is utilized to drive the lens actuator with a low power (similar to 5 mW) to acquire data from targets placed at multiple depths, axially spanning a range of 5 mm. The proposed actuator was intended for use in a circumferentially scanning wireless capsule endoscopy to provide high-resolution imaging at multiple depth sections throughout the gastrointestinal tract. The proposed device, targeted for confocal imaging, comprises a laser source and a light detector, the 3D-printed focus adjusting actuator to address different layers, a prism integrated micro-motor for circumferential scanning. We showcase a proof of principle data acquisition from reflective targets placed at different depths, through utilizing a scanning micromotor in conjunction with the developed focus actuator. With further development, the proposed actuator can be adapted to clinical environment to perform optical biopsies.