A sensor arrangement for ascertaining physical properties of a liquid is proposed, having electro-acoustical converters (6) on a substrate (5) which are wettable with the liquid and are suitable for generating and detecting acoustical surface waves with predetermined wave modes. A Y-rotated quartz slice is used as the substrate (5), and above the substrate (5) is a waveguide layer (16); the standard of the Y rotation of the quartz slice and the material of the waveguide layer (16) are selected such that an extensive temperature compensation within the range of temperature of the liquid to be investigated is obtained.