Regensburg 2019 – wissenschaftliches Programm

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VA: Fachverband Vakuumphysik und Vakuumtechnik

VA 4: New Vacuum Gauges - Development and Characterization

VA 4.1: Hauptvortrag

Montag, 1. April 2019, 14:00–14:40, H6

Development of a new wireless SAW-Pirani vacuum sensor with extended range and sensitivity — •Sofia Toto and Juergen Brandner — Karlsruhe Institute of Technology

Vacuum sensors with a broad range are required for a number of applications. Many types of vacuum sensors already exist relying on various operating principles. One of their biggest drawback is their limited sensing range. In light of the recent technology and of the industry requirements, a new sensor aiming to sense a broader vacuum range extending from atmospheric pressure down to high vacuum has been developed. It uses state of the art microelectronics enabling efficient wireless power and signal transfer, resistant and stable materials that prevent outgassing and micromachining that allows a compact stable packaging in vacuum.

The sensor operates based on the Pirani principle and Surface Acoustic Waves (SAW-Pirani principle). A piezoelectric chip located inside a channel inserted in a vacuum environment is heated. The heat loss of the chip to its ambient through gas conduction is proportional to the number of molecules in the vacuum system. Temperature variations of the chip due to pressure changes in the vacuum chamber are detected by the change in frequency values of a crossing surface acoustic wave propagating on the surface of the chip via an interdigitated transducer. An interrogation signal is sent to the Interdigitated Transducer (IDT) and the frequency shift due to the pressure is recorded by the reflected signal. The vacuum pressure can therefore be calculated from the temperature of the heated body.