Improved micromachining of all SU-8 3D structures for a biologically-inspired flying robot

Abstract

This work describes the design and micromachining of all-SU-8 structures for a bio-mimetic flying micro-air-vehicle. The design based on simple analytical and finite-element model was briefly discussed to understand and optimize the structural sizes. The micromachining was improved from our previous works, utilizing a new process featuring ultra-thick AZ 4562 sacrificial layers. To obtain a large wing displacement, the process was improved to double the gap and to compare with our previous work. A sacrificial layer of thickness up to 90μm was realized by a single coating, exposure and development. The gap between the ring and the beam at wing root was enhanced to 120μm. As-prepared structures can generate a flapping angle of 40–70°, which depends on morphologic and geometric details of the pivot zone, thus able to emulate those of some insects. Passive torsion of the flapping wings necessary for lift generation was evidenced. We also describe the electromagnetic actuator used to move the wings. Our process allows an easy realization of a truly 3 dimensional (3D) SU-8 structure.