A Miniaturized Quartz Crystal Microbalance (QCM) Measurement Instrument Based on a Phase-Locked Loop Circuit

Abstract

The quartz crystal microbalance (QCM) has been widely used in laboratory settings as an analytical tool for recognizing and discriminating biological and chemical molecules of interest. As a result, recent studies have shown there to be considerable attention in practical applications of the QCM technique beyond the laboratory. However, most commercial QCM instruments are not suitable for off-laboratory usage. For field-deployable applications and in situ detection, the development of a portable QCM measurement system achieving comparable performance to benchtop instruments is highly desired. In this paper, we describe the development of a fully customizable, miniaturized, battery-powered, and cost-efficient QCM system employing a phase-locked loop (PLL) electronic circuit-based QCM measurement system. The performance of this developed system showed a minimum frequency resolution of approximately 0.22 Hz at 0.1 s measurement time. This novel, miniaturized system successfully demonstrated an ability to detect two common volatile organic compounds (VOCs), methanol and dichloromethane (DCM), and the obtained results were comparable to responses from a commercially available benchtop instrument.

Non-invasive biomedical sensors for early detection and monitoring of bacterial biofilm growth at the point of care

“…The possibility of portable QCM sensors has been recently confirmed to detect volatile compounds. 132 Surface acoustic wave (SAW) sensors. Surface acoustic wave (SAW) sensors use SAW to detect the biofilm thickness and biomass (Fig.…”

“…The possibility of portable QCM sensors has been recently confirmed to detect volatile compounds. 132…”

Accurate Multi-Channel QCM Sensor Measurement Enabled by FPGA-Based Embedded System Using GPS

“…Unfortunately, it is well known in the field of time-frequency metrology that attaining higher measurement accuracy necessitates longer measurement times. To mitigate this, QCM systems incorporate a phase-locked loop (PLL) electronic circuit, which reduces the measurement time [20]. Nevertheless, such systems are neither cost-effective nor suitable for developing a multi-channel QCM system.…”

Strategies for the Accurate Measurement of the Resonance Frequency in QCM-D Systems via Low-Cost Digital Techniques

“…Even if many low-complexity and low-cost measurement systems with very good metrological characteristics have been proposed in the literature or are commercially available, which exploit oscillators and measure the frequency of a sine wave produced by a feedback amplifier with the quartz embedded in the loop [ 17 ], or zero-phase lock-in circuits [ 54 ], no relevant low-cost accurate solution has yet emerged regarding the QCM-D technique [ 55 , 56 ].…”