Real-time and online large-scale temperature and humidity monitoring is urgently needed in industrial and agricultural production, food and drug storage, and some engineering applications. Since it is difficult to use electrical sensors in building large-scale distributed sensing networks and they have poor stability in some complex and harsh environments, a polyimide-coated (PI-wFBG) weak fiber Bragg grating array based on a drawing tower integrated preparation method is proposed for large-scale distributed humidity sensors. An approximately 4 km-length PI-wFBG array with a coating thickness of 12 mu m and grating spacing of 2 m was prepared, and six consecutive sensors were randomly selected for the determination of the relative humidity sensitivity and verification of the stability, repeatability and accuracy of the method. The experimental results showed that the relative humidity sensitivity of the prepared PI-wFBG array humidity sensor was concentrated at 1.4 +/- 0.1 pm/RH (the RH ranged from 21 RH to 90 RH) and the average sensitivity consistency deviation was within 3 ; the short-term stability fluctuation was within +/- 2.5 RH and the repeatability and accuracy deviations were <= 1.5 RH and <= 2 RH, respectively. Furthermore, the PI-wFBG array prepared by the drawing tower online method had features of adjustable grating spacing and customizable length, enabling it to be more adaptable and flexible in large-scale application scenarios.
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