High Fundamental Frequency (HFF) Monolithic Resonator Arrays for Biosensing Applications: Design, Simulations, and Experimental Characterization

Miniaturized, high-throughput, cost-effective sensing devices are needed to advance lab-on-a-chip technologies for healthcare, security, environmental monitoring, food safety, and research applications. Quartz crystal microbalance with dissipation (QCMD) is a promising technology for the design of such sensing devices, but its applications have been limited, until now, by low throughput and significant costs. In this work, we present the design and characterization of 24-element monolithic QCMD arrays for high-throughput and low-volume sensing applications in liquid. Physical properties such as geometry and roughness, and electrical properties such as resonance frequency, quality factor, spurious mode suppression, and interactions between array elements (crosstalk), are investigated in detail. In particular, we show that the scattering parameter, S
₂₁
, commonly measured experimentally to investigate crosstalk, contains contributions from the parasitic grounding effects associated with the acquisition circuitry. Finite element method simulations do not take grounding effects into account explicitly. However, these effects can be effectively modelled with appropriate equivalent circuit models, providing clear physical interpretation of the different contributions. We show that our array design avoids unwanted interactions between elements and discuss in detail aspects of measuring these interactions that are often-overlooked.