UBC Theses and Dissertations

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UBC Theses and Dissertations

Development of a pneumatic PDMS MEMS actuator using a closed loop controller for endoscopic applications Moallemi, Ali


Gastrointestinal (GI) cancer is one of the most significant public health issues globally. Early diagnosis results in increasing the probability of surviving GI cancers. However, it is difficult to develop diagnostic tools for early GI cancer detection. One of the challenges is to design an endoscope with adequate optical quality. This thesis demonstrated a pneumatic miniaturized PDMS (Polydimethylsiloxane) MEMS (Microelectromechanical Systems) actuator with high stability to improve optics. Theoretical, experimental, and simulation methods were used to characterize the actuator. An electronic platform with a PID (Proportional–Integral–Derivative) controller was designed to control the actuator. A feedback control mechanism was designed to eliminate disturbances, and provide a stable position for the actuator. A trial-and-error method, the Matlab® PID Tuner, and Genetic Algorithm were used to find and verify the PID parameters. To demonstrate the functionality of the actuator, a confocal system was used to obtain images of paper fiber and onion epidermis. The actuator shows an axial resolution of 1.12 μm and the optical resolution of 21.5 μm. The actuator designed in this study has several advantages, such as ease of miniaturization and stability that make it attractive for further development.

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