Microbar sensor

An apparatus for detecting the presence of a predetermined vapor phase chemical in a monitored atmosphere comprising:

• a piezoelectric transducer having at least one cantilevered spring element secured thereto, said spring element having an area portion along substantially the entire length thereof coated with a chemical having an affinity for said predetermined vapor phase chemical;
• oscillator means for stimulating said transducer at or about the resonant vibrational frequency of said cantilevered spring element;
• and,
• vibration detection means for measuring a vibrational frequency change in said spring element due to a change in the vibrated mass of said spring element.

A method for detecting the presence of a predetermined vapor phase chemical in a monitored atmosphere comprising the steps of:

• fabricating a cantilever spring element having a structural base secured to a piezoelectric transducer;
• coating a surface portion of said spring element along substantially the entire length thereof with a chemical having an affinity for said predetermined vapor phase chemical;
• electrically driving said transducer at or near a resonance frequency of said spring element.
• exposing said coated and driven cantilever spring element to a monitored atmosphere,
• measuring a vibrational frequency change of said cantilever spring element over a predetermined time period in said monitored atmosphere;
• and
• relating said vibrational frequency change to a concentration value of said predetermined vapor phase chemical in said monitored atmosphere.