• Optics and Precision Engineering
  • Vol. 31, Issue 22, 3279 (2023)
Guoyi KANG1, Yisheng ZHONG1, Jiaxin JIANG2, Xianruo DU1, and Gaofeng ZHENG1,*
Author Affiliations
  • 1Department of Instrumental and Electrical Engineering, Xiamen University, Xiamen36000, China
  • 2School of Mechanical and Automotive Engineering, Xiamen University of Technology, Xiamen361000, China
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    DOI: 10.37188/OPE.20233122.3279 Cite this Article
    Guoyi KANG, Yisheng ZHONG, Jiaxin JIANG, Xianruo DU, Gaofeng ZHENG. Low-temperature direct writing fabrication of flexible humidity sensors[J]. Optics and Precision Engineering, 2023, 31(22): 3279 Copy Citation Text show less

    Abstract

    The low-temperature, high-bonding direct writing of three-dimensional conductive structures poses a challenge to the manufacturing of flexible electronic composite devices. Based on the silver-ammonia complexation mechanism, a particle-free direct writing solution suitable for forming three-dimensional conductive structures has been developed in this study. The problem of metal particle aggregation was overcome, achieving long-term stability. Under low-temperature sintering conditions at 50 °C, the conductive fibers prepared using the silver-ammonia complex solution exhibit excellent conductivity, with resistance as low as 365 Ω/mm, surpassing those made with silver nanoparticle solutions. The fiber structures produced using the silver-ammonia complex solution have strong adhesion to flexible substrates and possess good self-stacking characteristics. By adjusting the number of fiber stacking layers from 10 to 50, the resistance of the conductive fibers can be controlled within the 6.7-34.1 Ω/mm range. A humidity sensor designed based on the silver-ammonia complex solution was tested in different saturated salt solutions to establish humidity environments. The sensor demonstrated excellent humidity responsiveness, with hysteresis as low as 3.2%, and exhibited ideal real-time response even under high humidity conditions. The particle-free direct writing solution holds promising prospects in the fabrication of flexible electronic products and finds wide applications in fields such as motion detection and health management.
    RT=1(σA)-1+RC(1)

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    response=R0-RR0×100%(2)

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    Guoyi KANG, Yisheng ZHONG, Jiaxin JIANG, Xianruo DU, Gaofeng ZHENG. Low-temperature direct writing fabrication of flexible humidity sensors[J]. Optics and Precision Engineering, 2023, 31(22): 3279
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