An Amplitude Analysis-Based Magnetoelastic Biosensing Method for Quantifying Blood Coagulation

Abstract

Blood coagulation tests are crucial in the clinical management of cardiovascular diseases and preoperative diagnostics. However, the widespread adoption of existing detection devices, such as thromboelastography (TEG) instruments, is hindered by their bulky size, prohibitive cost, and lengthy detection times. In contrast, magnetoelastic sensors, known for their low cost and rapid response, have garnered attention for their potential application in various coagulation tests. These sensors function by detecting resonant frequency shifts in response to changes in blood viscosity during coagulation. Nevertheless, the frequency-based detection approach necessitates continuous and precise frequency scanning, imposing stringent demands on equipment design, processing, and analytical techniques. In contrast, amplitude-based detection methods offer superior applicability in many sensing scenarios. This paper presents a comprehensive study on signal acquisition from magnetoelastic sensors. We elucidate the mathematical relationship between the resonant amplitude of the response signal and liquid viscosity, propose a quantitative viscosity measurement method based on the maximum amplitude of the signal, and construct a corresponding sensing device. The proposed method was validated using glycerol solutions, demonstrating a sensitivity of 13.83 V^-1/Pa^0.5s^0.5Kg^0.5m^-1.5 and a detection limit of 0.0817 Pa^0.5s^0.5Kg^0.5m^-1.5. When applied to real-time monitoring of the coagulation process, the resulting coagulation curves and maximum amplitude (MA) parameters exhibited excellent consistency with standard TEG results (R² values of 0.9552 and 0.9615, respectively). Additionally, other TEG parameters, such as R-time, K-time, and α-angle, were successfully obtained, effectively reflecting viscosity changes during blood coagulation.

Keywords: blood coagulation; clot strength; magnetoelastic sensors; thromboelastography (TEG); viscosity measurement.

Figure 1

Schematic illustration of magnetoelastic liquid viscosity measurement.

Figure 2

Magnetoelastic measurement device. (A) Block diagram of the device; (B) fabricated circuit board; (C) sensitive element, sample pool, and solenoid coil (serving as the coupling coil). During measurement, the sensitive element is positioned within the sample pool, which is secured at the center of the coil.

Figure 3

Frequency scanning response of glycerol solution measurement. (A) Numerical simulation results; (B) experimental measurement results.

Figure 4

Linearity analysis of resonant voltage amplitude under varying viscosity damping conditions.

Figure 5

Frequency scanning response during coagulation: the red point indicates the maximum point of the corresponding response curve (the data were randomly selected from repeated experiments).

Figure 6

Coagulation profiles derived from example results. (A) Change curve of the reciprocal of the magnetoelastic sensor response amplitude (the results were calculated from the data in Figure 5); (B) TEG trace obtained simultaneously using the TEG 5000 hemostasis analyzer.

Figure 7

Comparison of quality control sample results: maximum amplitude (MA) from TEG analyzer vs. maximum viscous damping value from magnetoelastic measurement.

Figure 8

Linear regression analysis and validation between maximum amplitude and maximum viscous damping value.

Figure 9

Comparison of the TEG trace converted from magnetoelastic measurement results with that measured by the TEG analyzer (showing only the top half), and extraction of R, K, α-angle, and MA parameters.