Wearable Plant Sensors

The future of agriculture

By Jacob Kim

Introduction

In addition to modern conflict, looming climate change and natural disaster serves as another key motivator of hunger within the exponentially exploding human population. The United Nations claims that if we do not reach net-zero carbon emissions by 2050, we will face grave natural disaster, resulting in environmental deterioration. Such environmental impacts will continue to fuel the rise of hunger and must be stifled in order to accomplish Zero Hunger.

A key method to reduce the impacts of environmental atrophy is proper utilization of future-facing technology. Named by the World Economic Forum as one of 2023's top 10 emerging technologies, Wearable Plant Sensors are the future of agriculture.

What is it?

Wearable plant sensors are revolutionary flexible electronics made of plastic polymers that act as data collection tools that will allow for waste reduction, yield optimization, and increased efficiency during the agricultural production process. Sensors constantly collected by plant's physiology and ambient conditions. The data is then wirelessly transmitted, often using low-power protocols like Bluetooth, Zigbee, LoRaWAN etc. This data can be accessed through applications, cloud platforms or integrated with AI/ML models.

AI can then analyze this multi-parameter sensor data, along with other data like weather, soil conditions, images etc. to detect biotic and abiotic stresses, nutrient deficiencies, water requirements and presence of diseases or pests.

Various information that may be collected and analyzed falls into two general categories: phenotype analysis, and environmental monitoring.

Function

Phenotyping

Phenotyping is the analysis of observable characteristics. A key characteristic often analyzed with plant wearables is elongation. Flexible wearable plant sensors are most optimal in gauging plant elongation as it omits any chance of the loss of optical vision that time-lapse cameras often face when new branches or leaves grow. Plant wearable however, attach onto plants and analyze tensile strain, rather than providing visual data. The tensile strain that is gathered is translated into the length of which the analyzed plant grew over a period of time. In order to gain this data however, these plant sensors must be flexible enough to obtain proper data and prevent any plant growth inhibition. Plant growth data will allow farmers to analyze whether certain cultivating techniques or specific fertilizers are more effective than others in achieving maximum growth or growth rate.

Temperature is another key piece of information that can be collected by these revolutionary devices. The benefit of wearable plant sensors detecting both plant and environmental temperature is that it can contribute to deciding whether or not a plant is under water stress. Plants undergoing water stress could result in the production of reactive oxygen species which cause grave damage to biomolecules. Such damage will result in respiration reduction, photosynthesis reduction, and as a result: growth reduction. Particular plant wearables, shaped similar to paper clips, contain functions that both detect plant and environmental temperature. Through real applications on pumpkins and melons, researchers have found that the difference between exterior and plant temperature and water stress levels were negatively correlated. Such information will allow for farmers to immediately detect water stress, allowing them to adapt and reduce water usage or provide excess shelter from precipitation.

Wearable plant sensors have also revolutionized the method in which water content is tracked in plants. Current tracking methods such as thermal imaging are only applicable in laboratories, making wearable plant sensors a more effective way to analyze water content. The real-time monitoring provided by such plant wearables determines transpiration rates and water distribution within the plant by attaching them to leaves, stems, or branches. The least harmful way of applying such sensors is through the medium of a non-toxic adhesive tape. Moisture and resistance sensors embedded within such adhesive tape provides the ultimate device to analyze water content and distribution within plants. Ensuring that plants are properly hydrated will allow for proper photosynthesis and respiration, allowing for bountiful yields to attack hunger.

Stress response is an essential statistic that must be tracked in order to optimize agricultural activities. Wearable plant sensors containing this function are extremely crucial as they can detect early biotic or abiotic stresses such as pathogen and disease. Prior to the invention of such sensors, disease such as Phytophthora infestans which causes plant late blight were could never be detected early as it was often identified visually, and often too late. The gas sensor array with gold nanoparticles and graphene oxide on the plant wearable can detect volatile organic compounds approximately 100 hours prior to any symptoms emerge. Such early detection allows for early intervention and prevent further infection within fields. Alternative stress response sensors comprised of conductive polymer electrodes can detect other stressors such as Ultra ViolentA radiation and ozone stress. Real-time detection of such symptoms will allow for farmers to immediately ratify poor situations as quick as possible in order to boost agricultural productivity.

Phenotyping with the assistance of wearable plant sensors will expedite the process of agriculture, allowing for farmers to surge agricultural production.

Phenotyping with the aid of wearable plant sensors has the potential to revolutionize agricultural practices, accelerating the path towards sustainable intensification of crop production. By harnessing the power of these innovative sensing technologies, farmers gain unprecedented insights into the intricate physiological processes and environmental interactions that govern plant growth and development. Wearable sensors offer a continuous stream of real-time data, enabling precise monitoring of crucial parameters surrounding the plant.

Ultimately, the integration of wearable plant sensors into phenotyping practices presents a transformative opportunity to surge agricultural production while promoting resource-efficient and sustainable farming practices. By bridging the gap between cutting-edge technology and traditional agricultural wisdom, these sensors empower farmers to unlock the full potential of their crops, paving the way for a future where food security and environmental stewardship go hand in hand.

Environmental Monitoring

Wearable plant sensors offer a comprehensive monitoring capability, simultaneously acquiring data not only from the plant itself but also from the dynamic environmental conditions that encompass and influence its growth and development.

Environmental humidity plays a critical role in plant health and growth. Humidity directly influences the opening and closing of stomata, which regulates the transpiration rate. Optimal humidity levels are essential for facilitating proper water absorption, transpiration, and transport of mineral nutrients within the plant. However, humidity extremes can be extremely deteriorating. Excessively low humidity can cause wilting and leaf detachment as the plant attempts to conserve water, while excessively high humidity increases susceptibility to pest infestations, foliar diseases, and root diseases. Maintaining an ideal humidity range tailored to the specific plant's needs is crucial for creating an optimal growing environment.

A prime example of a wearable sensor designed to monitor environmental humidity is the ultralight, butterfly-shaped, flexible multi-sensor platform shown in Fig. 7Ai. This innovative sensor platform incorporates a humidity sensor with an interdigital design, utilizing polyimide (PI) as the sensing element. The capacitance of the PI sensor exhibits a high sensitivity to humidity, increasing proportionally with rising humidity levels. When conformably installed on a plant leaf (Fig. 7Aii), this sensor can facilitate real-time monitoring of the environmental humidity. By continuously tracking humidity data, farmers and horticulturists can make informed decisions to maintain optimal conditions, ensuring proper stomatal function and facilitating an ideal transpiration rate for the plant's growth and development.

Pesticides can be extremely dangerous to plant health and its negative impact can be limited with the implementation of proper plant wearables. Current pesticide residue detection relies on slow costly methods such as gas chromatography which is not extremely beneficial or practical. When tested, sensors such as Serpentine 3-electrode LIGs synthesized on a PI film and transferred to a PDMS substrate, immediately detected pesticides and communicated the results to a mobile device (shown in the figure on the right.) Immediate remediation will be possible with the help of such technology, preventing large contamination, ruining potentially fruitful yields.

Similar issues of unreliable existing methods of tracking pesticide residue are present when attempting to detect toxic gas. Gas sensor arrays based on SWCNT channels and graphite electrodes however, present an efficient solution. When DMPP gas or nitrogen dioxide gas had been exposed to such sensors, the sensor almost immediately detected the gasses and responded with greater intensity as the quantity of the gasses increased.

Plan and Process

If I could source the necessary materials, I would create a flexible plant wearable using a nickel electrode for its durability and conductivity. The electrode would wirelessly transmit data to an app on my phone, where I could monitor the plant's hydration in real time. This would ensure optimal moisture levels, conserving water and promoting plant health. Additionally, tracking hydration can indicate if the plant is free of toxins or pests, as proper moisture levels often correlate with overall well-being. This system would combine technology and sustainability to efficiently monitor plant health.

If the sensor proved to be effective within the variable group and proved to be the optimal situation for these plants I would then apply the sensor to a larger scale, such as the vegetable and fruit gardens that I had created in the Hope of the Mission homeless center in Northridge, CA. In a location where maximizing food production and minimizing waste is essential, wearable plant sensors would be extremely beneficial in the shelter's efforts to feed the unhoused.

Initially, I would test out the effectiveness of the plant sensor by utilizing it in a variable group of plants, such as green onions, and compare it to a control group without the sensor. Within the control group I would monitor and water the plant by eye, but with the variable group my brother would carefully follow the monitor and adjust my actions according to the sensor. The reason why I am not conducting both the variable and control group is to prevent my bias from experience with the variable or control group to manipulate my actions with the other group, thereby skewing the results.

Benefit

Production Optimization

Wearable plant sensors provide data that allows for precise irrigation management, effectively optimizing water usage and reducing water wastage. Water waste reduction is an essential mission we as a population must aim to accomplish. As of 2022, the United Nations stated that 2.2 billion people lacked safely managed drinking water. To negate this issue, we must properly utilize clean water, particularly in agriculture.

Farms in the United States currently waste approximately 21% to 33% of water. As food demand increases with exponentially increasing population, more water will continue to be wasted if proper measures are not put in place. The use of plant wearables with hydration level monitoring will allow for farmers to continuously monitor a plant's water content and deduce whether it is being under or over watered. The key to efficient water management is not applying nutrients or performing irrigation evenly on the whole field, but only in the amount that is required and in the areas that require it. Informed farmers will be equipped to make better decisions and optimize their water usage into areas that truly need it. Contemporary agricultural practices are plagued by inefficiencies that contribute to the widespread squandering of precious resources, with water and food being among the most significant casualties of unsustainable farming methods.

16% of the aforementioned waste of food occurs at the source: farmland. Proper agricultural practices with the help of constant and accurate data, farmers will be able to minimize waste due to poor hydration, temperature, pesticides, etc. Crops often suffer from such conditions due to the lack of information farmers have been plagued with for centuries. An experiment conducted by the Indian Institute of Technology Bombay practiced precision agriculture by using wearable plant sensors to measure soil moisture levels presented extremely promising results: 25% water reduction and 10% increase in yield.

In a world grappling with the dual challenges of a growing population and the pressing need for environmental stewardship, the adoption of technology-driven agricultural practices represents a crucial step towards a more sustainable and food-secure future. By harnessing the power of wearable sensors and precision agriculture, the agricultural sector can pave the way for a paradigm shift, where food waste is minimized, resource efficiency and yield is maximized, and the delicate balance between human needs and environmental preservation is restored.

Plant- Based Diets

The waste reduction and yield optimization is not the only benefit of wearable plant sensors: they push plant based life styles.

Plant-based diets should be the most common diet in the world yet only approximately 18.55% of the population have plant-based diets. The benefit of the diet has been acknowledged and confirmed by world renown universities such as Harvard and Yale. The analysis done by such universities have found that plant-based diets produce 75% less heat-trapping gas, generate 75% less water pollution, and use 75% less land than meat-rich diets. Currently, raising livestock for human consumption generates nearly 15% of total global greenhouse gas emissions, which is greater than all the transportation emissions combined. It also utilizes close to 70% of agricultural land and demands more water and fertilizer compared to any other food group, leading to deforestation, biodiversity loss, and water pollution. By opting to consume plant-based meals more regularly, individuals can significantly reduce greenhouse gas emissions and minimize land wastage.

Plant-based diets are also just as beneficial to the world as much as the individual. The MD Anderson Cancer Center at the University of Texas state that reduced risk for cancer, heart disease, stroke, diabetes, and mental health illnesses are heightened with the implementation of plant-based diets. They also have found that due to the increased consumption of fiber, a plant-based eater will have stabilized blood sugar and improved bowel movement. The complex nutrition content in vegetation allows for improved gut health which as a result will improve one's immune system and reduce inflammation.

If such environmental and personal health benefits do not convince and individual to become plant-based, price will. An additional benefit accompanied by the optimized production of food caused by plant wearable utilization is lowered prices. The University of Colorado Boulder states that when food loss/waste is reduced by 50 percent, price drops offset between one-half to two-thirds of that amount—along with the predicted environmental benefits. In a society where obesity and other health issues are prominent- particularly in America- access to healthy food is often the primary source of blame. Lowered prices will eliminate such blame, allowing for greater access to nutritious, environmentally-friendly, and delicious food.

The aforementioned environmental benefits of precision agriculture with sustainable plant wearables may be further reaped by attracting throngs of humans to practice plant-based consumption, further pushing the objectives of the United Nation's Sustainable Development Goals.

Not only do the impacts of wearable plant sensors promote sustainability, the sensor itself is sustainable. As they are designed to be lightweight, low-power, and have long operational lifetimes to minimize resource consumption and electronic waste, they present minimal environmental downside. Biodegradable and renewable materials like certain bioplastics, paper, wood, etc. are also being utilized to make the sensor substrates more eco-friendly.

Urgency

Wearable plant sensors represent a transformative technological advancement that will propel agriculture into a new era of unprecedented efficiency and sustainability. As the world's population continues its inexorable growth, coupled with the intensifying challenges posed by climate change and resource scarcity, the need for precision agriculture has never been more urgent. Wearable sensors offer a powerful solution, enabling farmers to optimize inputs precisely when and where they are needed, maximizing yields while minimizing waste and environmental impact.

The ability to continuously monitor plant health, stress levels, and microclimate conditions in real-time provides farmers with invaluable data-driven insights. This granular understanding empowers them to make informed decisions, precisely targeting interventions such as water, fertilizers, and pest management. By eliminating the guesswork and inefficiencies of traditional broad-scale practices, precision agriculture facilitated by wearable sensors promises to unlock new frontiers of resource efficiency and sustainability.