In this presentation we will explore the phenomenon of resonance in electrical, mechanical, optical and acoustic domains for sensing applications. The field of micro and nano sensors has rapidly evolved over the last couple of decades with many of the highest performance devices exploiting the phenomenon of resonance for sensing. Micro and nano scale resonator designs, fabrication, and integration of new materials offer unique opportunities for innovative, novel, and robust configurations impacting all aspects of sensor systems. The methods of coupling the resonator to the measurand will be discussed and example sensors for stress, infrared, and rotation (gyroscopic) applications will be presented. Important design considerations such as resonator geometry, the Q-factor, nonlinear behavior, power consumption and packaging will be analyzed. Furthermore, piezoelectric microelectromechanical systems (MEMS) resonant sensors are well known for their excellent mass resolution and have been studied for many applications, including DNA hybridization, protein–ligand interactions, and immunosensor development. And more recently, optical resonant microsensors with high sensitivity have been successfully demonstrated. These advances have allowed for miniaturization and cost-effective manufacturing of such optical resonant sensor devices. Furthermore, chip-scale integration of microfluidics with optics has enabled analyte preparation and delivery for optical interrogation by such sensing structures. The feedback mechanism based on microring, microtoroid and microdisk have been employed for shaping resonant transmission or reflection spectrum to improve spectral resolution. The presentation will conclude with a review the operation and performance of the first MEM-based zero-power wake-up receiver are described. This device uses the high quality factor of a MEM-device to achieve extremely low power sensitivity (-60 dBm at 750 MHz) without consuming power.