Abstract
Due to the influence of liquid load, the equivalent resistance of in-liquid quartz crystal microbalance (QCM) increases sharply, and the quality factor and resonant frequency decreases. We found that the change in the resonant frequency of in-liquid QCM consisted of two parts: besides the frequency changes due to the mass and viscous load (which could be equivalent to motional inductance), the second part of frequency change was caused by the increase of motional resistance. The theoretical calculation and simulation proved that the increases of QCM motional resistance may indeed cause the decreases of resonant frequency, and revealed that the existence of static capacitance was the root cause of this frequency change. The second part of frequency change (due to the increases of motional resistance) was difficult to measure accurately, and may cause great error for in-liquid QCM applications. A technical method to reduce the interference caused by this effect is presented. The study contributes to the accurate determination of the frequency and amplitude change of in-liquid QCM caused by liquid load, which is significant for the QCM applications in the liquid phase.
Highlights
Quartz crystal microbalance (QCM) has been used for a long time in vacuum and gaseous environments as an ultrasensitive mass sensor, especially for film thickness monitoring [1,2], humidity sensors [3,4,5], proximity sensors [6,7], and various gas sensors [8,9,10]
The liquid QCM resonant frequency change is comprised of two parts: the frequency change ∆ caused in-liquid QCM resonant frequency change is comprised of two parts: the frequency change ∆ f L caused by the added equivalent motional inductance
For in-liquid QCM applications, the liquid load was equivalent to a mass loading (L3 ) and
Summary
Quartz crystal microbalance (QCM) has been used for a long time in vacuum and gaseous environments as an ultrasensitive mass sensor, especially for film thickness monitoring [1,2], humidity sensors [3,4,5], proximity sensors [6,7], and various gas sensors [8,9,10]. With varying mass attached to one side of the electrode, the QCM resonant frequency changes . Since Nomura and Okuhara [13] showed that a QCM completely immersed in a liquid could be excited to stable oscillation [14]—which marked the beginning of the QCM’s applications in liquid phase—QCM has often been applied as electrochemistry sensors [15,16,17], biosensors [18,19,20,21], and immunosensors [22,23,24,25]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
