纺织基底无芯片RFID 湿度传感器

研制了一种无湿敏材料的纺织基底无芯片RFID 湿度传感器用于检测环境湿度。通过射频仿真软件 HFSS,获得谐振频率在2. 45 GHz 具有较高品质因数的纺织基底谐振器模型,对以谐振频率偏移量作为灵敏度指标 的检测原理进行了仿真。利用丝网印刷工艺和刻绘工艺分别在不同类型纺织物上制作了无芯片RFID 湿度传感器, 系统研究了制作工艺、纺织品类型和厚度对传感器湿敏特性的影响。结果表明,0. 5 mm 厚度下不同基底类型湿度传 感器的灵敏度由高至低依次为:棉基底、亚麻基底、聚酯纤维基底,恢复特性呈相反顺序,其中棉基底传感器在高湿 范围内平均灵敏度达3. 8 MHz/ %RH,聚酯纤维基底传感器恢复度达86%;相同类型的棉纺织基底下基底厚度越大, 平均湿度灵敏度越高,恢复特性越差。传感器稳定性测试表明传感器具有较好的中长期稳定性。对纺织基底湿度 传感器的感湿机理进行了分析,纺织纤维中的亲水基团与水分子间形成氢键,改变了基底的介电参数,传感器的湿 敏特性与组成纺织品的纤维成分、纤维细度、编织方式有关。

Chipless RFID Humidity Sensor Based on Textile Substrate

In this paper, a chipless RFID humidity sensor based on textile substrate without humidity sensitive material is developed to detect environmental humidity. The model of textile substrate resonator with high quality factor at resonance frequency of 2. 45 GHz is obtained by using HFSS, and the detection principle with resonance frequency offset as sensitivity index is simulated. The chipless RFID humidity sensors are fabricated on different types of textiles by screen printing and engraving processes respectively. The effects of manufacturing process, textile type and thickness on the humidity sensing property are systematically studied. The results show that the sensitivity of different substrate types of humidity sensors with the thickness of 0. 5 mm is in the order of cotton substrate, flax substrate and polyester fiber substrate, and the recovery characteristics are in the reverse order. The average sensitivity of cotton substrate sensor is 3. 8 MHz/ %RH in the high humidity range, and the recovery of polyester fiber substrate sensor is 86%. The greater the thickness of the same type of cotton textile substrate, the higher the average humidity sensitivity and the worse the recovery characteristics. The sensor stability test shows that the sensor has good medium and long-term stability. The moisture sensing mechanism of textile substrate humidity sensor is analyzed. The hydrogen bond between hydrophilic groups in textile fiber and water molecules changes the dielectric parameters of the substrate. The humidity sensitive characteristics of the sensor are related to the fiber composition, fiber fineness and knitting mode of the fabric.