Department of Information Engineering, University of Brescia, 25123 Brescia, Italy.
INO-CNR (National Institute of Optics-National Research Council), Via Branze 45, 25123 Brescia, Italy.
Biosensors (Basel). 2023 May 23;13(6):572. doi: 10.3390/bios13060572.
A passive flexible patch for human skin temperature measurement based on contact sensing and contactless interrogation is presented. The patch acts as an RLC resonant circuit embedding an inductive copper coil for magnetic coupling, a ceramic capacitor as the temperature-sensing element and an additional series inductor. The temperature affects the capacitance of the sensor and consequently the resonant frequency of the RLC circuit. Thanks to the additional inductor, the dependency of the resonant frequency from the bending of the patch has been reduced. Considering a curvature radius of the patch of up to 73 mm, the maximum relative variation in the resonant frequency has been reduced from 812 ppm to 7.5 ppm. The sensor has been contactlessly interrogated by a time-gated technique through an external readout coil electromagnetically coupled to the patch coil. The proposed system has been experimentally tested within the range of 32-46 °C, giving a sensitivity of -619.8 Hz/°C and a resolution of 0.06 °C.
提出了一种基于接触式传感和非接触式询问的被动式柔性人体皮肤温度测量贴片。该贴片作为一个 RL 谐振电路，嵌入一个用于磁耦合的感应铜线圈、一个作为温度传感元件的陶瓷电容器和一个额外的串联电感器。温度会影响传感器的电容，从而影响 RL 电路的谐振频率。由于增加了电感器，因此贴片弯曲对谐振频率的依赖性已降低。考虑到贴片的曲率半径可达 73 毫米，谐振频率的最大相对变化已从 812ppm 降低至 7.5ppm。通过外部读取线圈的时间门控技术，通过与贴片线圈电磁耦合的方式对传感器进行非接触式询问。在所研究的 32-46°C 范围内，对所提出的系统进行了实验测试，其灵敏度为-619.8Hz/°C，分辨率为 0.06°C。
