Recent advances in Micro Electro Mechanical Systems (MEMS), semiconductor sensors, and actuator chip-based technology, have incorporated many non-standard silicon processing materials in their design. The use of materials such as polymers in conjunction with standard CMOS processing and materials has enabled many new MEMS sensors and actuators to be created. Even though the design enabling flexibility of polymers maybe very high, the processing and implementation of polymers for a given application is often more complex than what is encountered with standard engineering materials due to their ubiquitous qualities. The main focus of this thesis is to investigate both the tensile mechanical properties of Polydimethylsiloxane (PDMS), a material increasingly used in MEMS, and large deflection membrane theory to provide more accurate tensile mechanical material properties and analytical membrane models for MEMS application design with PDMS.