Parylene MEMS technology for adaptive flow control of flapping flight

This thesis is the culmination of research work in developing a parylene MEMS technology to fabricate MEMS wings and large-area parylene actuator skins for real-time adaptive flow control for flapping flight applications.; In this thesis, the novel MEMS-based wing technology is presented using titanium-alloy metal (Ti-6Al-4V) as wingframe and parylene-C as wing membrane. With this technology, the ability to produce light, yet robust, 3-D wings can be achieved. The use of MEMS technology enables systematic research in terms of repeatability, size control, weight minimization, and mass production of the wings. By fabricating the wing with the photolithography and etching techniques, fast turnaround time of various wing designs can be easily obtained. The wings are optimized to utilize the flow separation to achieve a high lift coefficient, C_L, as large as five times that of the fixed-wing aircraft. The aerodynamic tests are performed in a high quality low-speed wind tunnel with velocity uniformity of 0.5% and speeds range from 1 to 10 m/s. The wind-tunnel test results are presented and discussed.; As part of the investigation to integrate MEMS actuators onto the wings for real-time adaptive flow control, the MEMS technology is developed to fabricate the first large-area wafer-sized, flexible parylene MEMS electrostatic actuator skins. The technology is first developed to fabricate parylene actuator diaphragm on a silicon chip. The actuator diaphragm is made of two metallized layers of parylene membranes with offset vent holes. Without electrostatic actuation, air can move freely from one side of the skin to the other side through the vent holes. With actuation, these vent holes are sealed and the airflow is controlled. The membrane behaves as a complete diaphragm. This function is successfully demonstrated using a 2-mm x 2-mm parylene diaphragm electrostatic actuator valves.; Finally, this technology is applied to fabricate large area wafer-sized actuator skins. The skins contain only parylene and metalized electrodes and have no bulk silicon as a structural component. Plate and check-valved skin types are fabricated and both are integrated onto the MEMS wings for aerodynamic flow control. The integration of micro-valved actuators has shown significant effect on the aerodynamic performance of the flapping flight. The wind-tunnel test results are analyzed and discussed in detail in this thesis.