Inductor–capacitor (LC) resonant sensors can provide low-cost, contactless measurement in closed environments. In this work, three fabrication methods to produce flexible LC sensors are compared: screen-printed pastes, etched copper-coated polyimide, and wound metal wires. The LC sensors were interrogated by near-field coupled antennas driven by a vector network analyzer. The sensor response was analyzed by extracting the resonant frequency (MHz) and the peak-to-peak amplitude (dB) of the $S_{21}$ scattering parameter. For screen-printed resonators, varying parameters such as print feature size (250 to $500\mathrm{\mu }\mathrm{m}$), conductive paste silver content (DuPont PE825 and 5028 for low and high silver content, respectively), curing condition (convection oven temperature and curing time), and paste viscosity (7.20–20.05​ Pa$\cdot$s) were explored. An empirical model was fit to this data to allow for prediction of required sensor line thickness needed to meet an application’s required step-off distance. The screen-printed resonant sensors were then compared to copper-etched and wound metal wires to evaluate the cost and performance tradeoff of the three fabrication approaches. Finally, a use case of the flexible, screen-printed resonant sensors was demonstrated by contact-free measurement of fluid level of in a closed, curved container.

电感电容（LC）谐振传感器可以在封闭环境中提供低成本，非接触式测量。在这项工作中，比较了生产柔性LC传感器的三种制造方法：丝网印刷浆料，蚀刻铜涂层聚酰亚胺和缠绕金属线。LC传感器被矢量网络分析仪驱动的近场耦合天线询问。通过提取传感器的谐振频率（MHz）和峰峰值幅度（dB）来分析传感器响应。${\mathrm{小号}}_{21}$ 散射参数。对于丝网印刷谐振器，各种参数（例如印刷特征尺寸（250至$500\mathrm{\mu }\mathrm{米}$），导电浆料的银含量（杜邦PE825和5028分别用于低和高银含量），固化条件（对流烤箱温度和固化时间）以及浆料粘度（7.20–20.05$\cdot$s）进行了探索。将经验模型拟合到此数据，以便预测满足应用程序所需的步距所需的所需传感器线宽。然后将丝网印刷的谐振传感器与铜蚀刻和缠绕的金属线进行比较，以评估三种制造方法的成本和性能之间的权衡。最后，通过非接触式测量密闭弯曲容器中的液位，演示了柔性，丝网印刷共振传感器的使用案例。