The measurement of humidity provides valuable information to a range of industries. Existing hygrometers lack the combination of high sensitivity/low detection-limit, temperature insensitivity, fast response, high robustness and low cost. We present a new design of humidity sensors based on the combination of a polymer-coated multimode fiber interrogated by a light sheet (i.e. thin plane of light) designed to precision excite the optimum group of skew rays for enhanced sensitivity. The sensing mechanism is water absorption of light via evanescent-wave interaction mediated by a polymer-coated multimode fiber. For a 10.0 bilayer poly(diallyldimethylammonium) (PDDA)/poly(styrenesulfonate) (PSS)-coated sensing fiber, we demonstrated a sensitivity of up to 0.14 dB/%RH/cm, a detection limit of 0.007%RH, a temperature cross-sensitivity of less than ˜0.13%/°C, and response/recovery times of 115 ms and 200 ms. The tested dynamic range is between 10%RH and 94%RH. The dependence on the total optical power rather than the phase of light makes such sensors relatively insensitive to temperature while remaining sensitive to humidity. The PDDA/PSS functional coating inherently offers fast response. The use of multimode fibers and power meters make such fiber-optic sensors highly robust and relatively inexpensive, easing the translation to practical applications.

湿度的测量为许多行业提供了有价值的信息。现有的湿度计缺乏高灵敏度/低检测极限，温度不灵敏度，快速响应，高鲁棒性和低成本的组合。我们提出了一种新的湿度传感器设计，该技术基于聚合物涂层的多模光纤的组合，该纤维被光片（即薄光平面）询问，该光片旨在精确激发最佳偏斜射线组以增强灵敏度。感测机制是通过由聚合物涂层的多模光纤介导的e逝波相互作用来吸水。对于10.0双层聚（二烯丙基二甲基铵）（PDDA）/聚（苯乙烯磺酸盐）（PSS）涂层的传感光纤，我们证明了灵敏度高达0.14 dB /％RH / cm，检测极限为0.007％RH，温度交叉-灵敏度小于〜0。13％/°C，响应/恢复时间分别为115 ms和200 ms。测试的动态范围在10％RH至94％RH之间。依赖于总光功率而不是光的相位，使得这种传感器对温度相对不敏感，而对湿度仍然敏感。PDDA / PSS功能涂料固有地提供了快速响应。多模光纤和功率计的使用使此类光纤传感器非常坚固且相对便宜，从而简化了向实际应用的转换。