A 3D-printed 3D actuator for miniaturized laser scanning probes

Abstract

Imaging of tissue sections at multiple depths with a miniaturized optical imaging probe necessitates 3D actuation capability. A number of MEMS studies in literature have addressed 3D actuation either through a single scanning unit with three degrees of freedom, or combination of multiple scanning units each having one or more degrees of freedom in scanning. Such microsystems are manufactured with high fabrication complexity while only offering a limited (typically < 0.5 mm) actuation capability in the axial dimension whereas advances in the adaptive optics and wave-front shaping allow for light penetration up to several millimeters within the tissue. In an effort to address deep tissue slices that light can penetrate using adaptive optics, here we present a 3D printed Polyamide-based 3D actuator with hybrid hydraulic and electromagnetic actuation mechanisms. Our actuator is able to provide up to 3 mm axial displacement in air (and 4 mm in tissue), with only a pumped fluid pressure of 500 kPa. Furthermore, the actuator provides 5 degrees total optical scan angle in the lateral directions, with 5 Vrms drive voltage that is applied to the coil. Overall, the device is manufactured in a compact form factor, having 10 mm diameter and 45 mm length, making it suitable for endoscopic or within hand-held probe use. Using selective laser sintering process in manufacturing the actuator allows for low-cost and rapid manufacturing capability making the device attractive for use in disposable laser scanning probes for imaging within the gastrointestinal tract.