The rapidly growing demand for humidity sensing in various applications such as noninvasive epidermal sensing, water status tracking of plants, and environmental monitoring has triggered the development of high-performance humidity sensors. In particular, timely communication with plants to understand their physiological status may facilitate preventing negative influence of environmental stress and enhancing agricultural output. In addition, precise humidity sensing at bio-interface requires the sensor to be both flexible and stable. However, challenges still exist for the realization of efficient and large-scale production of flexible humidity sensors for bio-interface applications. Here, a convenient, effective, and robust method for massive production of flexible and wearable humidity sensor is proposed, using laser direct writing technology to produce laser-induced graphene interdigital electrode (LIG-IDE). Compared to previous methods, this strategy abandons the complicated and costly procedures for traditional IDE preparation. Using graphene oxide (GO) as the humidity-sensitive material, a flexible capacitive-type GO-based humidity sensor with low hysteresis, high sensitivity (3215.25 pF/% RH), and long-term stability (variation less than ± 1%) is obtained. These superior properties enable the sensor with multifunctional applications such as noncontact humidity sensing and human breath monitoring. In addition, this flexible humidity sensor can be directly attached onto the plant leaves for real-time and long-term tracking transpiration from the stomata, without causing any damage to plants, making it a promising candidate for next-generation electronics for intelligent agriculture.

在诸如无创表皮传感，植物水状态跟踪和环境监测等各种应用中，对湿度传感的需求迅速增长，引发了高性能湿度传感器的发展。特别是，与植物进行及时的交流以了解其生理状况可能有助于防止环境压力的负面影响并提高农业产量。此外，生物界面的精确湿度感测要求传感器既灵活又稳定。然而，实现用于生物界面应用的柔性湿度传感器的有效和大规模生产仍然存在挑战。在此，提出了一种方便，有效且鲁棒的方法，用于大量生产柔性可穿戴湿度传感器，使用激光直接写入技术生产激光诱导的石墨烯叉指电极（LIG-IDE）。与以前的方法相比，该策略放弃了传统IDE准备过程中复杂且昂贵的过程。使用氧化石墨烯（GO）作为湿度敏感材料，具有低滞后性，高灵敏度（3215.25 pF /％RH）和长期稳定性（变化小于±1％）的柔性电容式GO型湿度传感器获得。这些优越的性能使该传感器具有多功能应用，例如非接触式湿度感测和人类呼吸监测。此外，这种灵活的湿度传感器可以直接连接到植物叶片上，以实时，长期地跟踪气孔中的蒸腾作用，而不会对植物造成任何损害，