A Mass-Position Sensing Scheme Using a Geometrically Adjustable Resonator With Low-Order Modals for Detecting Multiple Analytes

Mechanical resonators are widely used to detect small quantities of adsorbed single mass without position information through shifts in oscillation frequency while there have been always facing with urgent needs and severe challenges around synchronously sensing mass and position of multiple analytes. A mass-position synchronous sensing scheme is therefore proposed using a length-adjustable single cantilever with low-order modes (i.e., the first two ones) for multiple analytes in this article. A theoretical expression is derived to elucidate the relationship between mass and position of multiple spheres and modal frequencies of the cantilever with different lengths, and a corresponding algorithm is programed to synchronously sense mass and position of multiple spheres. Compared to that of the multimodal one (i.e., more than three), the position detection error of the proposed scheme is decreased to about 50% and 47 % in the cases of two and three spheres, respectively. The number of detectable spheres is unlimited by changing modal frequencies with adjusting cantilever length in the proposed scheme while that is limited by the measurable modes in the multimodal one. It is observed that the mass-position detection accuracy is improved by enlarging the interval among the adsorbable positions both in analytical and experimental studies.