Baron, Sergio DanielThis thesis demonstrates the design, fabrication and testing of a platform for in situ stress/strain measurement in lithium ion battery electrodes. The platform - consisting of a Microelectromechanical System (MEMS) chip containing an electrochemical cavity and an optical sensing element, a custom electrochemical package and an experimental setup - was successfully developed. Silicon was used as an active electrode material, and a thin-film electrochemical stack was conceived and tested. Finally, multiple experiments showed correlation between the active material volume change inside the battery and a signal change in the optical sensing element. The experimental results, combined with the MEMS implementation of the sensing element provide a promising way to evaluate electrochemical reaction-induced stress monitoring in a simple and compact fashion, while experiments are carried out in situ.ThesisElectrical engineeringBatteryIn situLithiumMEMSSiliconStress