Direct Fabrication of Microcantilever Structures with High Shape Accuracy Using Projection-Based Stereolithography.

Microcantilever structures such as microgears play an important role in precision mechanisms, where highly accurate cantilever characteristics guarantee the reliable function of these structures. Projection-based stereolithography (PSL) technology is widely used to fabricate sophisticated microstructures owing to its high precision and remarkable efficiency, and plenty of works have been done to improve the precision of structures with macroscale. However, the shape accuracy of microcantilever structures fabricated through PSL process is always neglected, which severely hinders its application in precision mechanisms. In this work, we investigated the influence of major factors on the shape accuracy of microcantilever structures in PSL process through orthogonal tests. Different resin materials were tested to investigate the influence of material properties. Printing experiments showed that for a given PSL system, microcantilever structures with confined size could be directly and accurately manufactured using a set of optimized processing parameters, which dramatically speed up the production process and effectively improved the reliability of microcantilevers. This work provides a comprehensive understanding of the capability of PSL to fabricate microcantilever structures and guides the manufacturing processes of micromechanisms with cantilever features, which effectually promotes the industrial application of PSL technology.

Autonomous Collision-Free Navigation of Microvehicles in Complex and Dynamically Changing Environments.

Self-propelled micro- and nanoscale robots represent a rapidly emerging and fascinating robotics research area. However, designing autonomous and adaptive control systems for operating micro/nanorobotics in complex and dynamically changing environments, which is a highly demanding feature, is still an unmet challenge. Here we describe a smart microvehicle for precise autonomous navigation in complicated environments and traffic scenarios. The fully autonomous navigation system of the smart microvehicle is composed of a microscope-coupled CCD camera, an artificial intelligence planner, and a magnetic field generator. The microscope-coupled CCD camera provides real-time localization of the chemically powered Janus microsphere vehicle and environmental detection for path planning to generate optimal collision-free routes, while the moving direction of the microrobot toward a reference position is determined by the external electromagnetic torque. Real-time object detection offers adaptive path planning in response to dynamically changing environments. We demonstrate that the autonomous navigation system can guide the vehicle movement in complex patterns, in the presence of dynamically changing obstacles, and in complex biological environments. Such a navigation system for micro/nanoscale vehicles, relying on vision-based close-loop control and path planning, is highly promising for their autonomous operation in complex dynamic settings and unpredictable scenarios expected in a variety of realistic nanoscale scenarios.