Fraunhofer Institute for Silicon TechnologyDr. Fabian Stoppel
Surface acoustic wave sensors
Sensors based on the modulation of surface acoustic waves (SAW) can be used to measure various physical phenomena: In addition to mass absorption, elastic, viscoelastic or electrical effects can be exploited. Dedicated functional layers allow a wide range of applications with pressure, humidity, electric field, vibration, gas, bio or magnetic field sensors.
Motivation
A special feature common to all SAW sensors is that they are suitable for measuring both static and rapidly changing states. Based on the SAW technology platform, ISIT is currently developing a high performance current sensor with a dynamic range of 6 orders of magnitude and a bandwidth of up to 20 MHz in cooperation with the Christian-Albrechts-Universität zu Kiel and the Fraunhofer Institute for Applied Solid State Physics. This sensor is designed to precisely measure the very fast switching processes (~kA/ns) of modern switched-mode power supplies and thus enable highly efficient power conversion. The functional layer of this sensor consists of a magnetostrictive layer that causes a field-dependent modulation of the SAW wave by changing the elastic modulus.
Technology
The special feature of the SAW sensor technology at ISIT is that it is not based on volume crystals such as quartz. Instead, ISIT's SAW sensor elements are manufactured entirely in CMOS and MEMS-compatible silicon technology. This is only made possible by the use of the high-performance piezoelectric thin-film material AlScN. In addition to the high technology compatibility, further advantages are a higher process flexibility with regard to the integration of functional layers, a reduced chip size as well as the possibility to fuse different sensors on one chip.
Applications
- Efficient energy conversion:
- Electromobility
- Renewable energies
- Lighting
- Feedback and control:
- Smart Home
- Motors
- Industry
- Data center monitoring
Functional diagram of a surface acoustic wave sensor
