Multiplexing surface acoustic wave sensors with delay line coding

A surface acoustic wave (SAW) device, comprising:

• a piezoelectric substrate;
• and
• a plurality of SAW sensors attached to the piezoelectric substrate and arranged on a surface of the piezoelectric substrate, the plurality of SAW sensors including
• a first SAW sensor comprising a first delay line configured to propagate a first surface acoustic wave,
• wherein the first SAW sensor comprises a transducer positioned on the substrate and a first reflector and a second reflector, each positioned on the substrate opposite the transducer,
• wherein the transducer transmits the first surface acoustic wave along the first delay line, and the transducer receives the first surface acoustic wave after the first surface acoustic wave reflects off at least one of the first and second reflectors and propagates along the first delay line twice,
• wherein the first delay line comprises a guiding layer on the first delay line that confines propagation of the first surface acoustic wave and a sensitive layer on the guiding layer of the first delay line of each of the plurality of SAW sensors,
• wherein the guiding layer comprises at least one of a polymer, SiO2, or ZnO, and the sensitive layer attaches to or reacts with at least one analyte, and
• wherein the guiding layer extends along at least a portion of the first delay line;
• a second SAW sensor comprising a second delay line configured to propagate a second surface acoustic wave, wherein the second SAW sensor comprises a second transducer positioned on the substrate, wherein a length of the first delay line is greater than a length of the second delay line,
• wherein each of the plurality of SAW sensors is configured to simultaneously receive an excitation signal;
• and
• one or more processors in communication with each of the plurality of SAW sensors, the one or more processors configured to generate a receiving signal based on a signal received from the plurality of SAW sensors,
• wherein the receiving signal comprises a compressed pulse train having a plurality of pulses, each pulse corresponding to a respective one of the plurality of SAW sensors.