Real-Time Monitoring of Platelet Activation Using Quartz Thickness-Shear Mode Resonator Sensors

Abstract

In this study, quartz thickness-shear mode (TSM) resonator sensors were adopted to monitor the process of platelet activation. Resting platelets adhering to fibrinogen-coated electrodes were activated by different concentrations of thrombin (1, 10, and 100 U/mL), and the corresponding electrical admittance spectra of TSM resonators during this process were recorded. Based on a bilayer-loading transmission line model of TSM resonators, the complex shear modulus (G' + jG″) and the average thickness (hPL) of the platelet monolayer at a series of time points were obtained. Decrease in thrombin concentration from 100 to 1 U/mL shifted all peaks and plateaus in G', G″, and hPL to higher time points, which could be attributed to the partial activation of platelets by low concentrations of thrombin. The peak value of hPL was acquired when platelets presented their typical spherical shape as the first transformation in activation process. The G' peak appeared 10 ∼ 20 min after hPL peak, when some filopods were observed along the periphery of platelets but without obvious cell spreading. As platelet spreading began and continued, G', G″, and hPL decreased, leading to a steady rise of resonance frequency shift of TSM resonator sensors. The results show high reliability and stability of TSM resonator sensors in monitoring the process of platelet activation, revealing an effective method to measure platelet activities in real-time under multiple experimental conditions. The G', G″, and hPL values could provide useful quantitative measures on platelet structure variations in activation process, indicating potential of TSM resonators in characterization of cells during their transformation.

Non-Destructive Evaluation Device for Monitoring Fluid Viscosity

“…For instance, in the oil and petroleum industry, viscosity measurements play a vital role in determining the oil quality that can affect the pipeline [6]. In the healthcare industry, monitoring blood viscosity is crucial for the treatment of some diseases, such as vascular-related diseases [7]. Standard laboratory viscometers, such as capillary tube and rotating ones, need long measurement times and a large volume sample [8].…”

“…Thus, there is an increasing need for accurate, real-time, and low-cost viscosity measurement devices. Hence, a wide variety of devices have been developed over the years to establish high sensitivity, small size, easy of manufacture and use, real-time measurement, and low-cost [7,[10][11][12]. Modern viscosity measurement devices can be categorized based on their operational principle of monitoring parameters (a) displacement, (b) vibrations, and (c) wave propagation in fluids of different viscosities [4,13,14].…”

“…Lu et al [22] propose a piezoelectric-excited membrane device using the PVDF membrane's resonant frequency and Q factor responses to determine viscosity. Thickness shear mode resonators are other examples which use piezoelectric patches with electrodes on both sides [2,7]. The resonator is excited when an AC voltage is applied to the piezoelectric leads, thus changing the vibration characteristics for the resonator.…”

“…Similarly, quartz thickness-shear mode sensors are adapted to measure viscosity [7]. This sensor, in particular, monitors the process of platelet activation, which leads to thrombus formation (clotting).…”

“…This sensor, in particular, monitors the process of platelet activation, which leads to thrombus formation (clotting). By following the sensors admittance frequency shifts concerning different concentrations of platelet activation, coagulation can be detected [7]. Purohit et al [24] report a radial mode piezo-resonator disc to improve the ultrasonic determination of viscosity in liquids by correlating resonant frequency changes to viscosity.…”