Speaker
Description
Microelectromechanical systems (MEMS) are a success story of modern engineering with billions of MEMS sensors in automotive, consumer and industrial use. However, despite decades of research, limitations persist. One fundamental aspect of MEMS sensor performance centers on how a MEMS resonator interacts with its environment. These interactions can be highly complex and modelling them has been restricted to slender geometries limiting the available design space. A challenging example is the interaction with a liquid environment which is essential for bio- and fluid sensing. Conventional beam resonators suffer from quality factors well below 100 in liquids severely degrading sensitivity. By developing modeling methods that move beyond the beam paradigm toward non-slender plate geometries while retaining computational efficiency, we show that MEMS plate resonators reach quality factors above 300 in water representing a significant advance for bio and liquid sensing. A second fundamental limitation in MEMS is noise. Cavity optomechanics has shown that thermal and measurement noise can be reduced to the ultimate quantum-mechanical limits. Yet real-world applicability remains constrained by bulky optical components and cryogenic requirements. Our work pursues two strategies to bring these concepts into a scalable MEMS platform. First, the established vacuum-gap capacitor platform for quantum electromechanics is advanced toward higher operating temperatures through niobium as a superconducting material. Second, the electromagnetic cavity is replaced by a mechanical GHz surface acoustic wave (SAW) resonator fabricated with standard MEMS processes. We demonstrate parametric coupling between this SAW mode and low-frequency flexural cantilever modes establishing a mechano-mechanical analogue of cavity optomechanics on a single silicon chip. Our findings demonstrate that MEMS still have not reached their limits and have great potential for groundbreaking future applications.