From August 22 to 26, 2022, ACHEMA will once again be the meeting place for the global process industry. In addition to the trade fair, technology providers, users and researchers will be organizing an extensive congress program in Frankfurt in order to master future challenges facing the process industry.
In the session “Instrumentation, control and automation techniques – Sensor Connectivity and Protection” on Aug. 23, 2022, Dr. Heike Wünscher from the CiS Research Institute will report in her presentation “Passivation of silicon based MEMS flow sensors” on passivation options for MEMS sensors as flow sensors in harsh environmental conditions.
Sensors for mechanical quantities require mechanical contact with the measurand. However, direct media contact is usually problematic because the media resistance of the sensor cannot always be guaranteed. In order to take full advantage of miniaturization, corrosion protection was applied at the chip level. The sensor developed consists of four piezoresistive strain-sensitive measurement resistors interconnected to form a Wheatstone bridge.
With a focus on long-term stability of the protective coatings against body fluids or extreme pH-value spreads, various passivation coatings were evaluated, differing in their chemical composition, application areas and technology. At the same time, the resistance of silicon, as the basis of various piezoresistive pressure sensors, was increased by doping adjustments. This enables the use in more demanding environments such as aqueous solutions, in medical applications without additional protective structures. The performance of the sensors is not impaired in the process.
The research and development work in the project “Long-term stable passivation of piezoresistive sensors for demanding sensor environments” (PassDru) was funded by the German Federal Ministry for Economic Affairs and Climate Action.
Funding code: 49MF170089