A Real-Time Method for Improving Stability of Monolithic Quartz Crystal Microbalance Operating under Harsh Environmental Conditions

Abstract

Monolithic quartz crystal microbalance (MQCM) has recently emerged as a very promising technology suitable for biosensing applications. These devices consist of an array of miniaturized QCM sensors integrated within the same quartz substrate capable of detecting multiple target analytes simultaneously. Their relevant benefits include high throughput, low cost per sensor unit, low sample/reagent consumption and fast sensing response. Despite the great potential of MQCM, unwanted environmental factors (e.g., temperature, humidity, vibrations, or pressure) and perturbations intrinsic to the sensor setup (e.g., mechanical stress exerted by the measurement cell or electronic noise of the characterization system) can affect sensor stability, masking the signal of interest and degrading the limit of detection (LoD). Here, we present a method based on the discrete wavelet transform (DWT) to improve the stability of the resonance frequency and dissipation signals in real time. The method takes advantage of the similarity among the noise patterns of the resonators integrated in an MQCM device to mitigate disturbing factors that impact on sensor response. Performance of the method is validated by studying the adsorption of proteins (neutravidin and biotinylated albumin) under external controlled factors (temperature and pressure/flow rate) that simulate unwanted disturbances.

Quartz Crystal Microbalance with Impedance Analysis Based on Virtual Instruments: Experimental Study

“…The use of the QCM sensor in experimental conditions characterized by temperature and flow gradients is subject to uncertainty. Uncertainty is determined by some intrinsic effects related to sensor configuration, such as mechanical stress exerted by the measuring cell or electronic noise of the passive interrogation system, as well as external factors such as temperature, humidity, vibration or pressure can strongly affect the stability of the sensor [26], masking the signals of interest and degrading the limit of detection. Isolating the QCM sensor response from these factors is not trivial and the growing complexity and cost of testing equipment hinders the development of portable tools for real-time applications.…”

Advanced Impedance Spectroscopy for QCM Sensor in Liquid Medium

“…An ideal configuration, from which both internal and external factors that disturb the stability of the QCM sensor are eliminated, cannot be achieved experimentally because it is impossible to make portable equipment for large-scale applications of the QCM sensor. Temperature changes [ 16 ] mostly affect the behavior of the QCM sensor, and active temperature control can in turn become a noise source. If the liquid medium is biological, then the working temperature is imposed by it, and its stabilization usually involves significant experimental resources.…”

Design of a Novel Nanosensors Based on Green Synthesized CoFe2O4/Ca-Alginate Nanocomposite-Coated QCM for Rapid Detection of Pb(II) Ions

“…The sensor is very sensitive and is based on quartz crystals. For the very sensitive and precise detection of heavy metal ions in aqueous environments, several QCM sensors have been designed and coated with layers of tiny molecules [ 14 , 15 , 16 , 17 , 18 ]. However, the drawbacks of using tiny molecules in fabrication devices make it difficult to design QCM sensors for use in continuous media.…”