High-frequency bulk acoustic resonant microbalances in liquid

In this paper, we present two types of high-frequency bulk acoustic resonant microbalances based on (1) film bulk acoustic resonator (FBAR) and (2) high-tone bulk acoustic resonator (HBAR). Both resonators are operating at about 900 MHz, hundred times higher than a typical quartz crystal microbalance (QCM). Mass sensitivities of the FBAR and HBAR microbalances are measured to be 782.7 (50 times larger than that of QCM) and 9.3 cm²/g, respectively. The minimum detectable frequency changes for the FBAR and HBAR are measured to be about 2 and 0.1 kHz, respectively. Based on the mass sensitivities and minimum detectable frequency changes, the minimum detectable mass change for the FBAR and HBAR are estimated to be 4 ng/cm² (comparable to that of QCM) and 10 ng/cm², respectively