Micro-Scale Flapping Wings for the Advancement of Flying MEMS

This research effort presents conceptual micro scale air vehicles whose total dimensions are less than one millimeter. The initial effort was to advance the understanding of micro aerial vehicles at sub-millimeter dimensions by fabricating and testing micro scale flapping wings. Fabrication was accomplished using a surface micromachining process called PolyMUMPs™. Both rigid mechanical structures and biomimetic devices were designed and fabricated as part of this effort. The rigid mechanical structures focused on out of plane deflections with solid connections and assembling a multiple hinge wing structure through the aid of residual stress. These devices were actuated by double hot arm thermal actuators. The biomimetic structures derived from three different insect wings to include; the dragonfly, house fly, and butterfly were selected based off of an attribute that each insect possesses in nature. The dragonfly was chosen for its high maneuverability and hovering capabilities. The house fly wing was chosen because of its durability and the butterfly wing was chosen because of its flexibility. The fabricated wings utilize a thermal bimorph structure consisting of polysilicon and gold which allows device actuation through joule heating. The released micro wings had an initial upward deflection due to residual stress between the gold and polysilicon material layers. Joule heating, from an applied bias, forces the wing to deflect downward due to the coefficient of thermal expansion mismatch between the material layers. Each fabricated bio-wing structure was tested for deflection range as well as operating frequency. From the experimental testing of the micro scale flapping bio-wings, aerodynamic values were calculated to include; aspect ratio, reduced frequency in a hover, Reynolds number of a hovering device, drag force, and gravitational force. The research verified insect based wings on the micro scale are capable of producing the desired flapping motion

Conceptual Study of Rotary-Wing Microrobotics

This thesis presents a novel rotary-wing micro-electro-mechanical systems (MEMS) robot design. Two MEMS wing designs were designed, fabricated and tested including one that possesses features conducive to insect level aerodynamics. Two methods for fabricating an angled wing were also attempted with photoresist and CrystalBond™ to create an angle of attack. One particular design consisted of the wing designs mounted on a gear which are driven by MEMS actuators. MEMS comb drive actuators were analyzed, simulated and tested as a feasible drive system. The comb drive resonators were also designed orthogonally which successfully rotated a gear without wings. With wings attached to the gear, orthogonal MEMS thermal actuators demonstrated wing rotation with limited success. Multi-disciplinary theoretical expressions were formulated to account for necessary mechanical force, allowable mass for lift, and electrical power requirements. The robot design did not achieve flight, but the small pieces presented in this research with minor modifications are promising for a potential complete robot design under 1 cm2 wingspan. The complete robot design would work best in a symmetrical quad-rotor configuration for simpler maneuverability and control. The military’s method to gather surveillance, reconnaissance and intelligence could be transformed given a MEMS rotary-wing robot’s diminutive size and multi-role capabilities