an acoustic wave sensor assembly includes piezoelectric material , a first acoustic wave resonator element structure mounted on the piezoelectric material for interacting with an electrical signal , the acoustic wave resonator element structure being operable to interact with an acoustic wave propagating within the piezoelectric material to produce a first frequency response . further acoustic wave resonator element structures are mounted on the piezoelectric material for interacting with electrical signals , the further acoustic wave resonator element structures being operable to interact with further acoustic waves propagating within the piezoelectric material to produce subsequent frequency responses . the first acoustic wave resonator element structure and further acoustic wave resonator element structures are combined to form a ladder or lattice filter network to produce an overall frequency response . sensitive areas are mounted on the piezoelectric material and associated with the acoustic wave resonator element structures which , if predetermined effects to be sensed or detected are present , are modified thereby to control the nature of the frequency responses with resultant specific perturbations of the combined frequency response and thereby provide information with respect to the predetermined effects to be sensed or detected .