A novel highly sensitive SAW strain sensor with in-built temperature measurement

In this contribution, we describe a novel temperature-compensated SAW strain sensor for remote sensing. Temperature is the most important disturbance variable in SAW sensors, and this motivates the search for methods to suppress the temperature influence. The sensor design proposed consists of two SAW structures each comparable to a delay line and exploits electrical loading and multiple-transit signals. The interdigital transducers (IDTs) are connected in a way that leads to a sensor signal with a frequency spectrum showing a certain number of minima depending on the distances between the IDTs. The frequencies of these minima are influenced by both strain and temperature. Their evaluation allows to extract a temperature compensated strain signal with a resolution of about 10 ppm.