This CD lab researches piezoelectric microelectromechanical sensors and actuators (PiezoMEMS). The aim is to significantly improve the sensitivity of PiezoMEMS by examining noise sources in piezoelectric materials and components and to significantly improve the responsivity of PiezoMEMS by examining non-linear bi-stable architectures with mechanical deflections of several tens of micrometers.

Microelectromechanical systems (MEMS) are one of the hidden pillars of our modern data and information-driven world. MEMS are microscopic devices with the ability to measure or capture observable quantities of their environment, interpret and analyze the measurements (e.g. with integrated electronics to provide a certain level of intelligence), and influence their environment in specific ways. This bidirectionality of MEMS, on the one hand perceiving the environment and on the other hand influencing it, is expressed by two different terms: sensors and actuators.

Silicon-based MEMS enable, for example, pressure sensors in automotive applications, motion sensors in game consoles and smartphones or cochlear implants. The latest developments currently penetrate application areas such as autonomous vehicles, real-time monitoring of chemical processes, remote surgery, augmented reality and many more. A major challenge here is the use under a wide range of environmental conditions and increasing miniaturization.

Piezoelectric MEMS (PiezoMEMS) use the change in electrical polarization and thus the appearance of an electrical voltage on solids when they are elastically deformed. Aluminum nitride (AlN)-based PiezoMEMS typically feature a simple, cost-effective design and deliver robust behavior even in difficult environments such as liquids.

This CD lab therefore aims to answer fundamental research questions inspired by the limitations of PiezoMEMS to bridge the gap between scientific knowledge and applications.

Especially with regard to miniaturization, MEMS sensors require extremely low intrinsic noise in their electrical output signal in order to achieve high signal-to-noise ratios. Intrinsic noise sources are not sufficiently understood, particularly in PiezoMEMS sensors, and are closely linked to the microstructure of the piezoelectric material. Therefore, this CD lab seeks to develop a better understanding of noise sources in AlN-based piezoelectric MEMS sensors by studying the relationship between material properties, fundamental noise mechanisms and dissipative energy loss mechanisms.

Miniaturization also leads to very small mechanical deflections in the sub-µm range, especially in PiezoMEMS. Therefore, a further focus is to investigate the nonlinear dynamic-mechanical behavior of bi-stable PiezoMEMS actuators with exceptionally high deflections in the range of several 10 µm.

The results will stimulate the research and development of new PiezoMEMS devices in the MEMS semiconductor industry, so that both MEMS manufacturers and of course consumers will benefit from the groundbreaking research in this CD laboratory.