Surface acoustic wave based humidity sensor apparatus with integrated signal conditioning

A humidity sensor apparatus with integrated signal conditioning, said apparatus comprising:

• a micro-electronic circuit processed on a substrate to provide on-chip signal conditioning internally, wherein said substrate is covered with a protective layer to protect said micro-electronic circuit;
• a film of surface acoustic wave media coated on top of said protective layer to couple with a surface acoustic wave, wherein a thickness of said film is optimized to raise a coupling rate of said surface acoustic wave and to improve a resolution and a sensitivity thereof;
• and
• at least two sets of interdigital transducers and a humidity-sensitive film deposited on top of said film and associated with said micro-electronic circuit, wherein said at least two sets of interdigital transducers comprises a sensing interdigital transducer set and a reference interdigital transducer set and wherein said micro-electronic circuit processes a frequency signal output from said at least two sets of interdigital transducers to thereby eliminate common mode noise from external interference and generate an output signal proportional only to a humidity value tested, thereby providing a single-chip solution with respect to said humidity sensor apparatus that includes a high signal-to-noise, a quick response time, and an enhanced sensing accuracy.

A method of forming a humidity sensor apparatus with integrated signal conditioning, said method comprising:

• providing a substrate;
• configuring a micro-electronic circuit on said substrate to provide on-chip signal conditioning internally;
• covering said substrate with a protective layer to protect said micro-electronic circuit;
• coating a film of surface acoustic wave media on top of said protective layer to couple with a surface acoustic wave, wherein a thickness of said film is optimized to raise a coupling rate of said surface acoustic wave and to improve a resolution and a sensitivity thereof;
• and
• depositing at least two sets of interdigital transducers and a humidity-sensitive film on top of said film and associating said at least two sets of interdigital transducers and said humidity-sensitive film with said micro-electronic circuit, wherein said micro-electronic circuit processes a frequency signal output from said at least two sets of interdigital transducers to thereby eliminate common mode noise from external interference and generate an output signal proportional only to a humidity value tested, thereby providing a single-chip solution with respect to said humidity sensor apparatus that includes a high signal-to-noise, a quick response time, and an enhanced sensing accuracy.