Differential acoustic wave sensors

Acoustic wave sensor device, comprising:

• an interdigitated transducer;
• a first reflection structure arranged on one side of the interdigitated transducer;
• a second reflection structure arranged on another side of the interdigitated transducer;
• a first resonance cavity comprising a first upper surface and formed between the interdigitated transducer and the first reflection structure;
• a second resonance cavity comprising a second upper surface and formed between the interdigitated transducer and the second reflection structure;
• wherein the second upper surface comprises a physical and/or chemical modification as compared to the first upper surface;
• and
• wherein the physical and/or chemical modification comprises a recess of the second upper surface.