| abstract |
The present disclosure describes an acoustic wave based apparatus (100, 220, 340, 460) which includes a number of piezoelectric substrates (101, 201, 301, 401), a plurality of acoustic wave devices (102, 222, 341, 402) each formed on a surface of at least one of the number of piezoelectric substrates, and a first layer (104-1, 225-1, 345-1) including a reversibly oxygen-binding compound formed on the surface of one of the number of piezoelectric substrates in association with at least a first acoustic wave device (102-1, 222-1, 341-1, 402-1). The apparatus includes circuitry (108, 109, 111, 208, 209, 211,311) configured to determine a level of ambient oxygen gas (O 2 ) based upon a differential in output frequencies (107-1, 107-2, 228-1, 228-2, 347-1, 347-2) between the first acoustic wave device (102-1, 222-1, 341-1, 402-1) and a second acoustic wave device (102-2, 222-2, 341-2, 402-2) caused by binding of the ambient O 2 to the reversibly oxygen-binding compound. |