Abstract
The impedance quartz crystal microbalance (QCMI) is a versatile and simple method for making accurate measurements of the QCM sensor electrical parameters. The QCM sensor provides access to the physical parameters of the sample beyond the mass per unit area by measuring the dissipation factor, or another equivalent, ensuring a detailed analysis of the surface. By establishing a cooperative relationship between custom software and modular configurable hardware we obtain a user-defined measurement system that is called a virtual instrument. This paper aims primarily to improve and adapt existing concepts to new electronics technologies to obtain a fast and accurate virtual impedance analyzer (VIA). The second is the implementation of a VIA by software to cover a wide range of measurements for the impedance of the QCM sensor, followed by the calculation of the value of lumped electrical elements in real time. A method for software compensation of the parallel and stray capacitance is also described. The development of a compact VIA with a decent measurement rate (192 frequency points per second) aims, in the next development steps, to create an accurate impedance analyzer for QCM sensors. The experimental results show the good working capacity of QCMI based on VIA.
Highlights
The main advantages of quartz crystal microbalance (QCM) are the simplicity and versatility of the method [1], described more than 60 years ago
Considering label-free biosensing in liquids, surface plasmon resonance (SPR) spectroscopy [15] has a limit of detection lower than the QCM
This work presented a QCM based on virtual impedance analyzer (VIA) and the most important results are compreThis work presented a QCM based on VIA and the most important results are comhensively shown
Summary
The main advantages of quartz crystal microbalance (QCM) are the simplicity and versatility of the method [1], described more than 60 years ago. The QCM sensor based on AT-cut quartz crystals can be used in liquid medium [2,3] and passive interrogation at resonance is currently the basic method [4,5,6]. One of the most suitable acoustic biosensors for real-time monitoring is the QCM sensor, commonly used as a direct label-free detection tool. The limit of detection of the QCM sensor is lower in comparison with surface acoustic wave (SAW) sensors [13], as in electronic nose applications [14]. Considering label-free biosensing in liquids, surface plasmon resonance (SPR) spectroscopy [15] has a limit of detection lower than the QCM sensor. The QCM sensor provides access to the physical parameters of the sample beyond the mass per unit area by measuring the dissipation factor, or another equivalent, ensuring a detailed analysis of the surface
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