Department of Physics & IUTA, University of Oviedo, Campus de Viesques, 33203 Gijón, Spain.
Department of Electrical Engineering, University of Oviedo, Campus de Viesques, 33203 Gijón, Spain.
Sensors (Basel). 2023 Feb 21;23(5):2372. doi: 10.3390/s23052372.
We demonstrate how resonant planar coils may be used as sensors to detect and quantify magnetic nanoparticles reliably. A coil's resonant frequency depends on the adjacent materials' magnetic permeability and electric permittivity. A small number of nanoparticles dispersed on a supporting matrix on top of a planar coil circuit may thus be quantified. Such nanoparticle detection has application detection to create new devices to assess biomedicine, food quality assurance, and environmental control challenges. We developed a mathematical model for the inductive sensor response at radio frequencies to obtain the nanoparticles' mass from the self-resonance frequency of the coil. In the model, the calibration parameters only depend on the refraction index of the material around the coil, not on the separate magnetic permeability and electric permittivity. The model compares favourably with three-dimensional electromagnetic simulations and independent experimental measurements. The sensor can be scaled and automated in portable devices to measure small quantities of nanoparticles at a low cost. The resonant sensor combined with the mathematical model is a significant improvement over simple inductive sensors, which operate at smaller frequencies and do not have the required sensitivity, and oscillator-based inductive sensors, which focus on just magnetic permeability.
我们展示了如何使用共振平面线圈作为传感器来可靠地检测和量化磁性纳米粒子。线圈的共振频率取决于相邻材料的磁导率和介电常数。因此，散布在平面线圈电路顶部的支撑基质上的少量纳米粒子可以被定量检测。这种纳米粒子检测可应用于创建新设备，以评估生物医学、食品质量保证和环境控制挑战。我们开发了一种用于射频感应传感器响应的数学模型，从线圈的自共振频率获得纳米粒子的质量。在该模型中，校准参数仅取决于线圈周围材料的折射率，而不取决于单独的磁导率和介电常数。该模型与三维电磁模拟和独立的实验测量结果进行了比较。该传感器可以在便携式设备中进行缩放和自动化，以低成本测量少量的纳米粒子。与简单的感应传感器相比，共振传感器和数学模型是一个重大改进，简单的感应传感器在较小的频率下运行，不具备所需的灵敏度，而基于振荡器的感应传感器则仅关注磁导率。
