Wearable plant sensors hold tremendous potential for smart agriculture. The United Nations announced that 2020 is the International Year of Plant Health (IYPH), emphasizing the importance of plant health to end hunger, reduce poverty, and protect the environment. According to the Food and Agriculture Organization (FAO), it is estimated that by 2050, the productivity of food needs to be increased by about 60% to feed approximately 10 billion people all over the world. Plant diseases cause around 20 to 40% of global crop loss annually. Plant diseases not only cause notable loss in food production but also reduce species diversity, affect mitigation of people, increase control costs, and pose negative influence on human health and global food security. In this regard, sensor technologies for early disease diagnosis are essential to shorten stakeholder response time, identify threat before pathogen spreads, and reduce pesticide usage by optimizing application timing and choice of pesticides. These sensors contribute significantly to the reduction of pesticide usage by facilitating optimized application timings and targeted pesticide choices. The deployment of wearable plant sensors not only revolutionizes agricultural practices but also signifies a decisive stride towards fortifying global food supplies, preserving ecosystems, and ensuring the vitality of both human and environmental health.
Various techniques have emerged in the field of plant health monitoring, encompassing imaging and spectroscopic methods, bionanosensors, and smartphone-based devices. While these methods offer promising avenues, imaging and spectroscopic sensors stand out as real-time and noninvasive options. However, these imaging methods indirectly assess plant health by analyzing optical characteristics, leading to limitations in sensitivity, selectivity, and intricate processing of the acquired images or spectral data. Alternative strategies, including remote sensing and electrophysiological sensing, have also surfaced for continuous monitoring. Although, remote sensing often lacks spatial precision and fails to target specific diseases. Similarly, electrophysiological sensors have primarily exhibited success in tracking water stress or diurnal plant rhythms. Therefore, the need persists for innovative sensor technologies capable of real-time monitoring and nuanced evaluation of plant health. Such advanced sensors must effectively identify a range of biotic and abiotic stresses, facilitating early pathogen detection, disease prevention, and enhanced plant growth and yield. Wearable electronics have gained substantial attention in research, finding diverse applications ranging from health monitoring and human-machine interaction to soft robotics. An interesting emerging frontier involves wearable electronics designed for plant health monitoring. These adaptable sensor devices can be affixed to various parts of host plants, such as roots, stems, and leaves, to observe the plant’s microenvironment and physiological responses. The growth of each plant hinges on intricate biological processes including photosynthesis, transpiration, respiration, and gas exchange. Central to these processes is the regulation of leaf epidermal pores known as stomata. For an accurate assessment of plant health, it becomes imperative to concurrently examine many of these biological processes and the corresponding environmental conditions. Recent advancements have yielded several multi-functional wearable systems tailored for continuous plant health monitoring. For example, in May 2022, researchers at ACS Applied Materials & Interfaces developed a groundbreaking wearable sensor for plant leaves. This innovation facilitates wireless data transmission to a smartphone app, enabling remote oversight of drought stress in gardens and crops. The device’s data is seamlessly conveyed to the app and a dedicated website. Additionally, through a rapid and straightforward machine learning technique, these data points are effectively translated into a measure of water content lost, indicating the percent of water depletion. The significance of monitoring water content on leaves extends beyond drought concerns. Indirectly, this data provides insights into potential exposure to pests and harmful agents. The efficacy of the plant-wearable system indoors has prompted the researchers to contemplate outdoor testing in gardens and crop fields. By deciphering optimal watering times, this technology holds the promise of conserving resources and elevating yields.
