Research on Flexible Wearable Leaf Humidity Sensor and Its Application in Melon Physiological Monitoring

doi:10.16420/j.issn.0513-353x.2025-0586

Acta Horticulturae Sinica ›› 2026, Vol. 53 ›› Issue (9): 2783-2896.doi: 10.16420/j.issn.0513-353x.2025-0586

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Research on Flexible Wearable Leaf Humidity Sensor and Its Application in Melon Physiological Monitoring

WANG Yingli¹, ZHANG Hongliang², AKEBAIERJIANG Kadeer², CHEN Xiansheng¹, BIE Zhilong², HUANG Yuan²^,^*()

¹ College of Engineering， Huazhong Agricultural University， Wuhan 430070， China
² National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops， College of Horticulture and Forestry Sciences，Huazhong Agricultural University， Wuhan 430070， China

Received:2025-06-29 Revised:2026-04-30 Online:2026-09-25 Published:2026-09-20
Contact: HUANG Yuan

Abstract

Abstract:

Using melon（Cucumis melo L.）as experimental material，this study conducted in-situ non-destructive monitoring of leaf water status under different stress conditions using sensors. Based on laser-induced graphene technology，this study developed a flexible wearable leaf moisture sensor for in situ monitoring of melon transpiration. The sensor was fabricated by patterning interdigitated electrodes on polyimide film and modifying the electrode surface with graphene oxide；After optimization，the optimized parameters were selected（7 pairs of interdigitated electrodes，350 μm width，and 100 μm spacing）. Performance tests demonstrated that the sensor exhibited high sensitivity in both capacitance and impedance modes（2.4 nF/% RH and 3.9 kΩ/% RH，respectively），along with robust resistance to temperature，light，and bending interference，while maintaining excellent stability over 20 days（fluctuation < 5%）. Application tests revealed that：（1）sensor attachment for 10 days caused no significant impact on melon leaf health；（2）it effectively identified melon leaf status under abiotic stress conditions，including temperature，low light，water deficit，and salinity；（3）it differentiated healing progress of grafted seedlings during graft union monitoring；（4）sensor capacitance was strongly correlated with transpiration rate and stomatal conductance（R² > 0.9）.

Key words: wearable sensor, leaf humility, laser-induced graphene, transpiration, non-destructive inspection, stress physiology, melon

CLC Number:

S652

WANG Yingli, ZHANG Hongliang, AKEBAIERJIANG Kadeer, CHEN Xiansheng, BIE Zhilong, HUANG Yuan. Research on Flexible Wearable Leaf Humidity Sensor and Its Application in Melon Physiological Monitoring[J]. Acta Horticulturae Sinica, 2026, 53(9): 2783-2896.

Figures/Tables 10

Fig. 1 Schematic diagram of the fabrication of a laser-induced graphene（LIG）based flexible humidity sensor

Fig. 2 Physical characterization of key materials for flexible humidity sensors A：Laser-induced graphene（LIG）interdigitated electrode diagram；B：Scanning electron microscopy（SEM）image of LIG；C：Hydrophilicity analysis of each component of the sensor

Fig. 3 Humidity response of sensors with different interdigital spacings based on capacitance and impedance modes

Fig. 4 Humidity response characteristics of sensors based on capacitance and impedance modes

Fig. 5 Environmental stability test of sensors in capacitance mode A：Different light intensities；B：Different temperatures；C：Different bending angles；D：Long-term capacitance stability under different humidity levels over 20 days. The same below

Fig. 6 Environmental stability test of sensors in impedance mode

Fig. 7 Effect of sensor attachment on the growth of melon leaves

Fig. 8 Capacitance response of melon leaves under different stresses A：Drought stress；B：Temperature stress；C：Under salt（NaCl）stress；D：Light stress. ** P < 0.01. Different lowercase letters indicate significant differences at P < 0.05 according to Duncan’s new multiple range test。The same below

Fig. 9 Monitoring of the graft healing process based on capacitance and leaf area index

Fig. 10 Correlation between sensor capacitance values and key leaf gas exchange parameters

References 36

[1]	Alam T, Saidane F, Al Faisal A, Khan A, Hossain G. 2022. Smart-textile strain sensor for human joint monitoring. Sensors and Actuators A:Physical, 341:113587. doi: 10.1016/j.sna.2022.113587 URL
[2]	Ali M A, Khan M A U, Rao A Q. 2024. Response of tomato plant to abiotic(heat stress)and biotic(tomato leaf curl New Delhi virus,ToLCNDV)factors. International Journal of Phytopathology, 13:99-107. doi: 10.33687/phytopath URL
[3]	Bras T A, Seixas J, Carvalhais N, Jagermeyr J. 2021. Severity of drought and heatwave crop losses tripled over the last five decades in Europe. Environmental Research Letters, 16:065012. doi: 10.1088/1748-9326/abf004
[4]	Chen R, Ren S, Li S, Han D, Qin K, Jia X, Zhou H, Gao Z. 2023. Recent advances and prospects in wearable plant sensors. Reviews in Environmental Science and Bio/Technology, 22:933-968. doi: 10.1007/s11157-023-09667-y
[5]	Chen Z, Lu C. 2005. Humidity sensors:a review of materials and mechanisms. Sensor Letters, 3:274-295. doi: 10.1166/sl.2005.045 URL
[6]	Fang S, Zhao P, Tan Z, Peng Y, Xu L, Jin Y, Wei F, Guo L, Yao X. 2022. Combining physio-biochemical characterization and transcriptome analysis reveal the responses to varying degrees of drought stress in Brassica napus L. International Journal of Molecular Sciences, 23:8555. doi: 10.3390/ijms23158555 URL
[7]	Frey C, Hernández Barriuso A, Encina A, Acebes J L. 2023. Non‐invasive monitoring of tomato graft dynamics using thermography and fluorescence quantum yields measurements. Physiologia Plantarum, 175:e13935. doi: 10.1111/ppl.v175.3 URL
[8]	Gebbers R, Adamchuk V I. 2010. Precision agriculture and food security. Science, 327:828-831. doi: 10.1126/science.1183899 pmid: 20150492
[9]	Gu Y, Zhang T, Chen H, Wang F, Pu Y, Gao C, Li S. 2019. Mini review on flexible and wearable electronics for monitoring human health information. Nanoscale Research Letters, 14:263. doi: 10.1186/s11671-019-3084-x pmid: 31372771
[10]	Heo J S, Eom J, Kim Y-H, Park S K. 2018. Recent progress of textile-based wearable electronics:a comprehensive review of materials,devices,and applications. Small, 14:1703034. doi: 10.1002/smll.v14.3 URL
[11]	Howell T A. 2001. Enhancing water use efficiency in irrigated agriculture. Agronomy Journal, 93:281-289. doi: 10.2134/agronj2001.932281x URL
[12]	Jayathilaka W A D M, Qi K, Qin Y, Chinnappan A, Serrano Garcia W, Baskar C, Wang H, He J, Cui S, Thomas S W, Ramakrishna S. 2019. Significance of nanomaterials in wearables:a review on wearable actuators and sensors. Advanced Materials, 31:1805921. doi: 10.1002/adma.v31.7 URL
[13]	Jiang H, Li Z, Jiang X, Qin Y. 2021. Effects of salt stress on photosynthetic fluorescence characteristics,antioxidant system,and osmoregulation of coreopsis tinctoria Nutt. HortScience, 56:1066-1072. doi: 10.21273/HORTSCI15956-21
[14]	Kamienski C, Soininen J P, Taumberger M, Dantas R, Toscano A, Cinotti T S, Maia R F, Neto A T. 2019. Smart water management platform:IoT-based precision irrigation for agriculture. Sensors, 19:276. doi: 10.3390/s19020276 URL
[15]	Kim J, Sempionatto J R, Imani S, Hartel M C, Barfidokht A, Tang G, Campbell A S, Mercier P P, Wang J. 2018. Simultaneous monitoring of sweat and interstitial fluid using a single wearable biosensor platform. Advanced Science, 5:1800880. doi: 10.1002/advs.v5.10 URL
[16]	Li Mingyan. 2018. Physiological and ecological response mechanisms of four common temperate tree seedlings to water and other ecological factors[Ph. D. Dissertation]. Jinan: Shandong University. (in Chinese)
	李明燕. 2018. 暖温带四种常见乔木幼苗对水分等生态因子的生理生态学响应机制[博士论文]. 济南: 山东大学.
[17]	Li Z, Mao H, Li L, Wei Y, Yu Y, Zhao M, Liu Z. 2024. A flexible wearable sensor for in situ non-destructive detection of plant leaf transpiration information. Agriculture, 14:2174. doi: 10.3390/agriculture14122174 URL
[18]	Liu H, Wang L, Lin G, Feng Y. 2022. Recent progress in the fabrication of flexible materials for wearable sensors. Biomaterials Science, 10:614-632. doi: 10.1039/D1BM01136G URL
[19]	Liu J J, Zhang Y C, Niu S C, Hao L H, Yu W B, Chen D F, Xiang D Y. 2023. Response of dahlia photosynthesis and transpiration to high-temperature stress. Horticulturae, 9:1047. doi: 10.3390/horticulturae9091047 URL
[20]	Liu Xin. 2021. Analysis of JJF 1101-2019 Calibration specification for temperature and humidity parameters of environmental testing equipment. Brand & Standardization,(2):99-101. (in Chinese)
	刘鑫. 2021. JJF 1101-2019《环境试验设备温度、湿度参数校准规范》探析. 品牌与标准化,(2):99-101.
[21]	Miner G L, Ham J M, Kluitenberg G J. 2017. A heat-pulse method for measuring sap flow in corn and sunflower using 3D-printed sensor bodies and low-cost electronics. Agricultural and Forest Meteorology, 246:86-97. doi: 10.1016/j.agrformet.2017.06.012 URL
[22]	National information and documentation standardization technical committee. 2010. Documentations-part 4:Non-book materials:GB/T GB/T 6999-2010. (in Chinese)
	全国信息与文献标准化技术委员会. 2010. 文献著录第4部分非书资料:GB/T 6999-2010.
[23]	Saneoka H, Moghaieb R E A, Premachandra G S, Fujita K. 2004. Nitrogen nutrition and water stress effects on cell membrane stability and leaf water relations in Agrostis palustris huds. Environmental and Experimental Botany, 52:131-138. doi: 10.1016/j.envexpbot.2004.01.011 URL
[24]	Song Bohua, Gao Ge, Gao Shan, Sun Linlin, Li Bingxue. 2022. Overview of the methods for sap flow measurement of standing tree based on thermal technology. Journal of Zhejiang A & F University, 39:456-464. (in Chinese)
	宋博华, 高歌, 高珊, 孙琳琳, 李冰雪. 2022. 基于热技术的活立木液流测量方法综述. 浙江农林大学学报, 39:456-464.
[25]	Sun W, Guo Z, Yang Z, Wu Y, Lan Y, Liao Y, Wu X, Liu Y. 2022. A review of recent advances in vital signals monitoring of sports and health via flexible wearable sensors. Sensors, 22 (20):7784. doi: 10.3390/s22207784 URL
[26]	Tan Zuojun, Cai Xia, Akebaierjiang Kadeer, Yu Fan, Lei Hongwei, Gao Ziyi, Yang Shuo, Huang Yuan. 2023. Nondestructive detection of graft union healing status in cucurbit seedlings using hyperspectral fluorescence tracing. Transactions of the Chinese Society of Agricultural Engineering, 39:276-282. (in Chinese)
	谭佐军, 蔡霞, 阿克拜尔江 · 卡德尔, 余帆, 雷红伟, 高子艺, 杨硕, 黄远. 2023. 高光谱荧光示踪无损检测瓜类作物嫁接苗愈合状态. 农业工程学报, 39:276-282.
[27]	Wan Xianchong, Meng Ping. 2007. Physiological and ecological mechanisms of long-distance water transport in plants. Chinese Journal of Plant Ecology, 31:804-813. (in Chinese) doi: 10.17521/cjpe.2007.0102
	万贤崇, 孟平. 2007. 植物体内水分长距离运输的生理生态学机制. 植物生态学报, 31:804-813. doi: 10.17521/cjpe.2007.0102
[28]	Wu S, Li Y, Wang Q, Cai Y, Teng P, Li W, Zhang F, Xu L, Wang S. 2025. Wearable plant sensing devices for health monitoring. Wearable Electronics, 2:100-115. doi: 10.1016/j.wees.2025.03.002 URL
[29]	Wu S, Xu C, Zhao Y, Shi W, Li H, Cai J, Ding F, Qu P. 2023. Recent advances in chitosan-based hydrogels for flexible wearable sensors. Chemosensors, 11 (1):39. doi: 10.3390/chemosensors11010039 URL
[30]	Xie Huayun, Ai Huijian, Hong Rixin, Qin Wu, Qin Sihua, Ye Yunfeng, He Yi, Li Guifen, Huang Jinyan, Liu Tangjing, Li Tianyan, Wei Zhengguang. 2021. Histological observation on the healing process of grafted rootstock and scion of thin skinned Cucumis Melo. Fujian Agricultural Science and Technology, 52 (9):59-63 (in Chinese)
	解华云, 艾辉建, 洪日新, 覃武, 覃斯华, 叶云峰, 何毅, 李桂芬, 黄金艳, 柳唐镜, 李天艳, 韦正光. 2021 薄皮甜瓜嫁接砧穗愈合过程组织学观察. 福建农业科技, 52 (9):59-63.
[31]	Yang H, Li Y, Wu M, Zhang Z, Li L, Wan S. 2011. Plant community responses to nitrogen addition and increased precipitation:the importance of water availability and species traits. Global Change Biology, 17:2936-2944. doi: 10.1111/gcb.v17.9 URL
[32]	Yang Yuzhen, Zhang Zhihao, Li Juan. 2018. Photosynthetic characteristics of oil peony‘Fengdan’and their relationship with environmental factors under different intercropping patterns. Chinese Journal of Ecology, 37:2905-2912. (in Chinese)
	杨玉珍, 张志浩, 李娟. 2018. 不同间作模式下油用牡丹‘凤丹’光合特性及其与环境因子的关系. 生态学杂志, 37:2905-2912.
[33]	Yan X, Pang Y, Niu K, Hu B, Zhu Z, Tan Z, Lei H. 2025. Wearable sensors for plants:status and prospects. Biosensors, 15:53. doi: 10.3390/bios15010053 URL
[34]	Yuan Y, Liu B, Li H, Li M, Song Y, Wang R, Wang T, Zhang H. 2022. Flexible wearable sensors in medical monitoring. Biosensors, 12 (12):1069. doi: 10.3390/bios12121069 URL
[35]	Zhang Zhenxing, Sun Jin, Guo Shirong, Tong Hui. 2011. Effects of supplemental calcium on the photosynthetic characteristics and fruit quality of watermelon under salt stress. Acta Horticulturae Sinica, 38 (10):1929-1938. (in Chinese)
	张振兴, 孙锦, 郭世荣, 童辉. 2011. 钙对盐胁迫下西瓜光合特性和果实品质的影响. 园艺学报, 38 (10):1929-1938.
[36]	Zhang Zhihong, Cheng Lin, Li Shuling, Peng Jiyong, Fang Wensong. 2015. Effects of dry-hot wind weather on physiology of winter wheat. Chinese Journal of Ecology, 34:712-717. (in Chinese)
	张志红, 成林, 李书岭, 彭记永, 方文松. 2015. 干热风天气对冬小麦生理的影响. 生态学杂志, 34:712-717.

Research on Flexible Wearable Leaf Humidity Sensor and Its Application in Melon Physiological Monitoring

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