Preliminary Study of Resonant Mass Sensors Based on Asymmetrically Gapped Cantilevers

Abstract

This paper reports the proof of concept of resonant mass sensors based on asymmetrically gapped cantilevers using a mesoscale prototype. The asymmetrically gapped cantilever structure helps to increase the displacement sensitivity significantly and consequently increases the mass resolution. The body of the mesoscale prototype was machined from an aluminum piece and the displacement sensing element was a lead zirconate titanate (PZT) sheet separated from the bottom mechanical beam. A PEEK (Polyetheretherketone) tubing was wrapped around the resonator for the flow-through measurement of liquid samples. The sensor was characterized with different liquid solutions. A minimum detectable density difference of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$6.0\times 10^{-5}\ {\rm g}\ {\rm cm}^{-3}$</tex></formula> was achieved. With a sample volume of 38 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu{\rm L}$</tex> </formula> , the minimum detectable mass was 2.3 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\mu{\rm g}$</tex></formula> .