Response of a quartz crystal microbalance to a liquid deposit

Abstract

Thec. ry has been developed for predicting the loss of response of a QeM to a liquid deposit due to viscous effects in the deposit. The lO~5 of response is expressed by a response factor, equal to the response of the OeM to a liquid film divided by its re::;ponsp. to a solid film of the same mass per unit area. The theory assumes a droplet-type deposit morphology. and considers the influence oC droplet distribution parameters. Experiments have heen conducted to examine the validity of the theory, using DC 704 silicone oil. as the subject deposit material. Experiments were made in two series -one with constant deposit mass and variable temperature. the other with variable deposit mass and constant temperature. Satisfactory agreement with the theory was found. Interpretation of the data using the theory has enabled information on droplet area coverage and number density to be deduced.

Humidity-sensing properties of a ZnO nanowire film as measured with a QCM

“…Another effect that leads to a deviation from the Sauerbrey equation may arise as a result of liquid deposits growing by condensation on the coated quartz crystal. In this case, after an initial decrease of the frequency shift, a subsequent increase can be observed due to the liquefaction of the adsorbed product [22]. After considering these issues, the positive frequency shift of our ZnO nanowires under varying relative humidity conditions can reasonably be ascribed to changes in the mechanical stiffness of the ZnO nanowire film on the QCM electrodes as a result of the interaction between water molecules (from the humid vapor conditions) and the ZnO nanowires.…”

“…(1) shows a linear relationship between mass uptake and frequency shift without considering the physical properties of the deposited solid film on the quartz crystal and describes negative frequency shifts occurring with increasing mass uptake into a rigid film on the quartz crystal. However unusual frequency shifts (i.e., positive and/or both positive and negative shifts) have been observed in the literature [20][21][22]. In fact, nonlinear or positive shifts in the reso- nance frequency of a quartz crystal arise from some perturbations in the physical and mechanical properties of the deposited film or material on the quartz crystal.…”

“…In environments of high humidity, condensation of water droplets inside or on the surface of a ZnO nanowire film structure is another possible process, which would effectively cause a positive shift in frequency as seen in Ref. [22].…”

Investigation of humidity sensing properties of ZnS nanowires synthesized by vapor liquid solid (VLS) technique

“…While the frequency shift decreases, Sauerbrey equation does not give any information about physical properties of the deposited solid film onto quartz crystal. But the large mass which was adsorbed onto ZnS nanowires coated quartz crystal can change the elastic properties of the ZnS nanowires and can cause to positive frequency shift [11,12]. The Sauerbrey equation is not valid for this condition and a different equation can be derived for considering the physical properties of the deposited solid film onto quartz.…”

The principles and applications of nano-diagnosis system for a nano-biosensor

“…Several applications have been published, including determination of ions, immunoassays, liquid chromatography and an electrochemical application. The frequency shift of the quartz crystals in contact with liquids has been studied [74][75][76][77][78][79][80]. Kanazawa et al [61] derived the following equation for ∆F from the equations of the shear stress relationship in the quartz crystal and for the liquid.…”