Surface acoustic wave (SAW) chemical multi-sensor array

Claim 1

A surface acoustic wave, multi-channel sensor which comprises a piezoelectric substrate; a bidirectional surface acoustic wave transducer disposed on the substrate; a plurality of pairs of acoustic sensing and reference channels, each pair member being substantially identical to its corresponding other pair member, the sensing channels being sequentially disposed on the substrate in juxtaposition with one side of the transducer and the reference channels being sequentially disposed on the substrate in juxtaposition with the other side of the transducer; each respective sensing channel and reference channel pair sequentially comprising a thin film whose composition is capable of absorbing a chemical vapor to be monitored, and a metallic surface acoustic wave grating reflector capable of receiving incident surface acoustic waves transmitted by the transducer through the thin film and reflecting them back again into the thin film to the transducer; for each channel pair, the reflector grating and thin film is spaced equidistantly from the center line of the bidirectional transducer such that each respective sensing channel and reference channel pair is a mirror image of the other; an acoustic absorber disposed on the substrate between each sensing channel and each reference channel; means for protecting each of the reference channels from ambient conditions and simultaneously exposing each of the sensing channels to ambient conditions; means for applying an RF signal to the transducer which causes the propagation of an acoustic signal into each of the sensing channels and reference channels; and means for detecting output signals from the transducer.

Claim 11

A method for detecting chemical contamination comprising the steps of: A.) providing a surface acoustic wave, multi-channel sensor which comprises a.) a piezoelectric substrate; b.) a bidirectional surface acoustic wave transducer disposed on the substrate; c.) a plurality of pairs of acoustic sensing and reference channels, each pair member being substantially identical to its corresponding other pair member, the sensing channels being sequentially disposed on the substrate in juxtaposition with one side of the transducer and the reference channels being sequentially disposed on the substrate in juxtaposition with the other side of the transducer; each respective sensing channel and reference channel pair sequentially comprising a thin film whose composition is capable of absorbing a chemical vapor to be monitored, and a metallic surface acoustic wave grating reflector capable of receiving incident surface acoustic waves transmitted by the transducer through the thin film and reflecting them back again into the thin film to the transducer; for each channel pair, the reflector grating and thin film is spaced equidistantly from the center line of the bidirectional transducer such that each respective sensing channel and reference channel pair is a mirror image of the other; d.) an acoustic absorber disposed on the substrate between each sensing channel and each reference channel; e.) means for protecting each of the reference channels from ambient conditions and simultaneously exposing each of the sensing channels to ambient conditions; f.) means for applying an RF signal to the transducer which causes the propagation of an acoustic signal into each of the sensing channels and reference channels; g.) means for detecting output signals from the transducer; and B.) applying an RF signal to the transducer and causing the propagation of an acoustic signal into each of the sensing channels and reference channels; and C.) detecting output signals from the sensing channels and the reference channels via the transducer.

Claim 12

A method for detecting chemical contamination comprising the steps of: A.) providing a surface acoustic wave, multi-channel sensor which comprises a.) a piezoelectric substrate; b.) a bidirectional surface acoustic wave transducer disposed on the substrate; c.) a plurality of pairs of acoustic sensing and reference channels, each pair member being substantially identical to its corresponding other pair member, the sensing channels being sequentially disposed on the substrate in juxtaposition with one side of the transducer and the reference channels being sequentially disposed on the substrate in juxtaposition with the other side of the transducer; each respective sensing channel and reference channel pair sequentially comprising a thin film whose composition is capable of absorbing a chemical vapor to be monitored, and a metallic surface acoustic wave grating reflector capable of receiving incident surface acoustic waves transmitted by the transducer through the thin film and reflecting them back again into the thin film to the transducer; for each channel pair, the reflector grating and thin film is spaced equidistantly from the center line of the bidirectional transducer such that each respective sensing channel and reference channel pair is a mirror image of the other; d.) an acoustic absorber disposed on the substrate between each sensing channel and each reference channel; e.) means for protecting each of the reference channels from ambient conditions and simultaneously exposing each of the sensing channels to ambient conditions; f.) means for applying an RF signal to the transducer which causes the propagation of an acoustic signal into each of the sensing channels and reference channels; g.) means for detecting output signals from the transducer; and B.) applying an RF signal to the transducer and causing the propagation of an acoustic signal into each of the sensing channels and reference channels; and C.) detecting output signals from the sensing channels and the reference channels via the transducer.