Viscosity Measurement Sensor: A Prototype for a Novel Medical Diagnostic Method Based on Quartz Crystal Resonator

Abstract

Viscosity variation in human fluids, such as Synovial Fluid (SF) or Cerebrospinal Fluid (CSF), can be used as a diagnostic factor; however, the sample volume obtained for analysis is usually small, making it difficult to measure its viscosity. On the other hand, Quartz Crystal Resonators (QCR) have been used widely in sensing applications due to their accuracy, cost, and size. This work provides the design and validation of a new viscosity measurement system based on quartz crystal resonators for low volume fluids, leading to the development of a sensor called “ViSQCT” as a prototype for a new medical diagnostic tool. The proposed method is based on measuring the resonance frequency at the crystal’s maximum conductance point through a frequency sweep, where crystals with 10 MHz fundamental resonance frequency were used. For validation purposes, artificial fluids were developed to simulate SFs and CFs in healthy and pathological conditions as experiment phantoms. A commercial QCR based system was also used for validation since its methodology differs from ours. A conventional rotational viscometer was used as a reference for calibration purposes. ViSQCT demonstrates the capability to measure the sample’s viscosity differentiation between healthy and pathological fluid phantoms and shows that it can be used as a basis for a diagnostic method of several pathologies related to the studied biological fluids. However, some performance differences between both QCR-based systems compared to the reference system deserves further investigation.

Portable Quartz Crystal Resonator Sensor for Characterising the Gelation Kinetics and Viscoelastic Properties of Hydrogels

“…The ViSQCT project of the Bioinstrumentation and Nanomedicine Laboratory (LBN) of the Universidad Politécnica de Madrid (UPM) developed a portable and low-cost sensor based on QCRs ( Figure 7 ) to measure the viscosity of a fluid with a small sample volume (tens of µL) [ 25 , 33 ]. As mentioned above, the most common use of QCRs is as QCMs, whose basis of operation was first established by Sauerbrey’s investigations, which describe the relationship between crystal resonance frequency shift and the added mass [ 34 ].…”

“…QCRs are mostly applied to sense mass, such as the quartz crystal microbalance (QCM) [ 21 , 22 , 23 ]. However, QCRs can also measure fluid viscosity [ 24 , 25 , 26 ]. One can determine the film’s thickness, shear modulus, and viscoelastic phase angle by measuring the dissipation of the acoustic wave in a film adhered to the quartz crystal’s surface [ 27 ].…”

Soft Capsule Magnetic Millirobots for Region-Specific Drug Delivery in the Central Nervous System

“…Prior to use, aCSF was filtered through a 0.22 μm filter. Density of aCSF is typically in the range of 1.008 mg/ml and viscosity is typically 1.01 mPa•s (Miranda-Martínez et al, 2021). MANiACs were then placed at the base of the inclines using a micropipette.…”

Precision Temperature Control System with Low EMI for Applications in Analyzing Thermal Properties of Highly Sensitive Piezoelectric Sensors

“…This allows for external factors to impact the resonant frequency and damping factor of the exposed crystal, which makes it possible to indirectly measure various physical quantities. QCM properties make it suitable for many applications in modern science such as biosensors [ 4 , 5 , 6 , 7 ], vapors and particulate matter sensors [ 8 , 9 , 10 ], systems for characterization of liquids [ 11 , 12 , 13 ], and aerospace [ 14 , 15 , 16 , 17 , 18 ]. Underlying most experiments are indirect measurements of mass changes and viscoelastic properties [ 19 ].…”