Micro-electro-mechanical systems (MEMS) are playing an increasingly pivotal role in manifold applications, fostering advancements in key technologies such as 5G and the Internet of Things (IoT). In particular, piezoelectric resonators are extensively adopted as building blocks of both sensor and RF filters due to their high quality factor and small footprint. In this thesis, we illustrate the design, fabrication, and measurement of Leaky Surface Acoustic Wave (LSAW) resonators that leverage the shear-horizontal acoustic mode present in the YZ 0° X-cut lithium niobate substrate. Through numerical simulations, we highlight the features that make them attractive especially for sensing applications, and optimize their electrode structure in order to maximize their main figures of merit: the electromechanical coupling and the quality factor.