Femtogram mass sensing platform based on lateral extensional mode piezoelectric resonator

This letter introduces a resonant mass sensor that is based on a lateral extensional mode piezoelectric resonator and has a minimum detectable mass of 10-15 g at room temperature and atmospheric pressure. The resonator with size of about 200×50×1 μ m3 has a quality factor (Q) of >1400 at 60 MHz, and as small as 0.1 ppm shift of its resonant frequency can be detected. The 0.1 ppm detection capability corresponds to a mass uncertainty of only about 4.6 fg. We have experimentally demonstrated a minimum detectable frequency shift of ∼1.6 ppm due to absorption of isopropanol vapor (73 fg) on the sidewalls of the parylene-coated lateral extensional mode piezoelectric resonator.