Silicone MEMS for fluidics

Citation

Grosjean, Charles (2001) Silicone MEMS for fluidics. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/j98f-v013. https://resolver.caltech.edu/CaltechETD:etd-09162005-105347

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. In this thesis, silicone rubber was integrated with standard silicon based micromachining processes to allow fabrication of large deflection actuators. Taking advantage of the low Young's modulus and resulting flexibility of silicone rubber, several different devices for fluidic control were demonstrated. A novel self-releasing process for defining large actuators on silicon substrates irrespective of backside opening size was developed and used to generate micro balloon actuators used for delta wing control. When deployed near the separation line on the rounded leading edge of a delta wing, significant aerodynamic moments were generated allowing flight control at high angle of attack. To allow more flexibility in spatial actuation, a flexible metal substrate actuator "skin" was also developed and tested on flight models. With vertical actuations of 2 mm, rolling moment coefficients up to 0.012 were obtained at high angle of attack, comparable to conventional flaps. The low durometer and flexibility of silicone rubber membranes were exploited to fabricate a peristaltic pump. Taking advantage of the low dead volume and good sealing afforded by membranes combined with form-fitting chambers, a self-priming pump capable of pumping gas and liquid with high particle immunity was demonstrated. Due to the planar nature of the device, it is straightforward to construct integrated systems of reservoirs, channels, valves, and pumps. Standalone operation without an external pneumatic source was achieved using thermopneumatic actuation with air as the working fluid. To achieve low power consumption and reasonable operational frequency, a suspended silicon island heater process was also developed. Flow rates up to 6.3 [...]/min at 291 mW power consumption were achieved with thermopneumatic actuation and flow rates above 100 [...]/min can be easily obtained with external pneumatic operation. Using technology developed for the peristaltic pump, a diaphragm pump topology suitable for complex fluidic systems was developed. By using a plurality of active valves and a single pumping chamber, fluids can be pumped from any input to any output. This can significantly reduce the number of pumps necessary for anything other than the simplest flow system. Using an improved thermopneumatic actuator, integrated flow systems can be constructed.

Thesis Files