Mass Sensitivity Of Quartz Crystal Microbalance Research Articles

Advances in the Mass Sensitivity Distribution of Quartz Crystal Microbalances: A Review.

A quartz crystal microbalance (QCM) is a typical acoustic transducer that undergoes a frequency shift due to changes in the mass of its surface. Its high sensitivity, robustness, small size design, and digital output have led to its widespread development for application in the fields of chemistry, physics, biology, medicine, and surface science. Mass sensitivity is one of the vital parameters and forms the basis for quantitative analysis using QCMs. This review firstly introduces the importance, definition, calculation, and measuring method of the mass sensitivity and then focuses on reviewing the influence of electrode parameters (including electrode shape, electrode diameter, electrode thickness, electrode material, etc.) on the mass sensitivity distribution of QCMs. Finally, the effect of the operating frequency on the mass sensitivity of QCMs is also analyzed.

Effect of Surface Modified Quartz Crystal Microbalance (QCM) on Detection Sensitivity for Prostate Specific Antigen (PSA)

In this work, the surface-modified quartz crystal microbalance (QCM) was utilized for prostate cancer biomarker detection. The electroplating method was highly utilized to modify the QCMs. The influence of electroplating time, corresponding nanostructure formation and surface-modified electrode sensitivity are investigated. The estimated frequency shift for unmodified QCM is 39 Hz, 30-minute modified QCM is 213 Hz, and 60-minute modified QCs is 483 Hz. This method is practically convenient to improve the mass sensitivity of the PSA detector. The mass sensitivity of QCM increased with electroplating time.

The Effect of Electrode Thickness on Mass Sensitivity of QCM Cannot Be Ignored.

Quartz crystal microbalance (QCM) has been widely used in various fields. The mass sensitivity of QCM that means the ratio between the resonant frequency shift and the mass change on the surface of the crystal wafer is a significant parameter. The accuracy of the mass sensitivity value can greatly affect the data analysis, which in turn affects the repeatability of the QCM-related experiment. Meanwhile, we noticed that most companies that provide QCMs do not give out specific electrode thickness values but a wide range of 400-10 000Å. In this letter, we quantitatively studied the effect of electrode thickness on mass sensitivity of QCM through theoretical calculation and experiment. The result shows the mass sensitivity of QCM with 10 000-Å thickness is 1.46 times and 2.08 times that of 1000- and 400-Å thickness, respectively. Obviously, the uncertainty in electrode thickness values provided by companies inevitably brings large experimental errors, which lead to inaccuracy and poor repeatability of QCM experiment. Therefore, we suggest that the companies providing QCMs should give the specific value of the electrode thickness, and then the researchers should also consider the influence of the electrode thickness when analyzing the data to improve the accuracy and repeatability.

Ultrasensitive quartz crystal microbalance enabled by micropillar structure

We report a method to significantly enhance the mass sensitivity of a quartz crystal microbalance (QCM) device in which Polymethyl Methacrylate (PMMA) micropillars were fabricated on QCM surface to form a two-degrees-of-freedom vibration system. PMMA micropillars were fabricated using nanoimprinting lithography technology. The QCM-micropillar coupled system exhibits a unique resonant frequency, near which the mass sensitivity of QCM can be enhanced by several orders of magnitude. Both numerical simulation and theoretical analysis were conducted to understand this improvement. Thereafter, ultrahigh sensitivity of the QCM-micropillar system was demonstrated by detecting a 1H, 1H, 2H, 2H-perfluorooctyl-trichlorosilane single monolayer film.

Wireless-electrodeless quartz-crystal-microbalance biosensors for studying interactions among biomolecules: A review

The mass sensitivity of quartz-crystal microbalance (QCM) was drastically improved by removing electrodes and wires attached on the quartz surfaces. Instead of wire connections, intended vibrations of quartz oscillators were excited and detected by antennas through electromagnetic waves. This noncontacting measurement is the key for ultrahigh-sensitive detection of proteins in liquids as well as quantitative measurements. This review shows the principle of wireless QCMs, their applications to studying interactions among biomolecules and aggregation reactions of amyloid β peptides, and the next-generation MEMS QCM, the resonance acoustic microbalance with naked embedded quartz (RAMNE-Q).