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There is a growing global interest in transitioning the current agricultural industry to one which is primarily based on precision agriculture (PA), which will require the employment of both advanced sensors and information technology to transform productivity rates in the field.
Since MEMS technology is associated with economical, precise and sensitive advantages, these sensors will undoubtedly play an important role in the rise of PA.
Adversities in Agriculture
Although historical agriculture arose from the transition from hunter-gatherer populations to agricultural societies, modern agriculture has been transformed by the technological advancements that have emerged over the past several centuries.
In addition to improving the overall tasks associated with daily agricultural work, these advancements have also been crucial to ensuring adequate food production to the rapidly growing global population.
Similarly, several methodologies have been utilized for their potential to improve agriculture outputs when certain unavoidable restrictions arise, such as severe changes in the climate, reduced rainfall and drastic temperature fluctuations.
Microelectromechanical systems (MEMS)-based sensors have presented a promising future in their capabilities to directly address these issues within the agricultural industry.
The Mechanism of MEMS Sensors
Since their original introduction into the public marketplace in 1986, millions of different devices based on MEMS sensor technology have been introduced and commercialized. Some of the most common applications of MEMS sensors include those incorporated into the printer heads of ink-jet printers, projection systems, drones, microphones, digital cameras, smartphones, biosensors, optical sensors, accelerometers and gyroscopes.
As inertial sensors, the most basic working principle of any MEMS sensor begins with a tilt that is applied to the small proof mass that is etched onto the silicon surface of the sensor’s integrated surface.
This force then creates a difference to exist within the potential, which is otherwise referred to as its displacement, which is measured by a position measuring interface circuit. Through the use of an analog-to-digital converter (ADC), this measurement is converted into digital signals that are then processed.
Being consistent with Newton’s second law of motion, which states that force is equivalent to mass times acceleration, the tilting, which can otherwise be understood as an applied acceleration, of the MEMS device will create a force that generates the displacement.
An accelerometer is therefore a crucial component of any MEMS sensor, as its function is to accurately measure the capacitance that is generated by the acceleration in relation to the moving small proof mass.
Piezoelectric accelerometers are widely known for their high accuracy and stability, which allows these devices to be independent of temperature and noise variations, while simultaneously consuming less energy.
Although the application of MEMS sensors within the automobile, healthcare and consumer goods industries have significantly increased over the past several years, the utilization of these sensors for agricultural purposes is a fairly new and exciting opportunity for this industry.
MEMS sensors are currently used to improve a number of agricultural conditions including that which involves the soil, environment, weed control, seedling and other components. Furthermore, these sensors are used for sap flow measurements and fruit diameter determinations within the production section of this industry.
MEMS Sensors For Soil
As a vital component of any agricultural project, the quality of the soil determines the productivity and yield of any crop. The most important aspect of this agricultural component that directly plays a role in the conductivity and moisture content of the soil is its pH, which reflects its acidity or basicity.
The ability for agricultural workers to accurately measure pH on a regular basis will regulate fundamental plant processes including photosynthesis, fertilization by pollination as well as various disease states.
A recent study on polymerization of agriculture MEMS sensors found that photocurable polymers, acrylic-based copolymers of both methyl methacrylate (MMA) and methacrylic acid (MAA), terpolymers and superabsorbent copolymers of itaconic acid exhibit pH sensing capabilities.
MEMS Sensors For Monitoring Environments
Solar radiation provides heat and energy to innumerable forms of life on earth to support the metabolic activities of human beings, warm the ocean and propel photosynthesis in plants.
During photosynthesis, the photosynthetically active radiation (PAR) of the sun, which can be in the wavelength range of 400 nanometers (nm) to 700 nm, is crucial. A recent 2018 study discussed the development of a novel PAR sensor based on an array of silicon diodes that accurately measured, recorded and stored information on light intensity, which proved its promising commercial viability in the future.
In addition to PAR, wind velocity can also play an interesting role in determining the productivity of agricultural lands. Whereas traditional wind velocity sensors are often mechanical or ultrasonic in their functioning principle, recent MEMS-based sensors have demonstrated their ability to accurately measure wind speed.
More specifically, cantilever-based MEMS sensors will bend when exposed to wind and obtain velocity measurements through either thermal or mechanical principles. For thermal MEMS sensors, a heated component of the sensor is exposed to air and will experience a certain amount of heat loss in relation to wind velocity.
The different MEMS-based agricultural sensors discussed here offer a promising future for this industry. Notably, the commercialization of these MEMS sensors will need to first overcome several challenges associated with this technology, which include the relatively high cost of MEMS sensors compared to traditional sensors and the power consumption of MEMS-based devices.
Additional concerns that must be addressed prior to the commercialization of these sensors include data reliability, sensitivity, security, scalability and management. While these challenges may be intimidating, they can act as a guiding tool for researchers as they move towards bringing their sensors to the market.
References and Further Reading
Singh, N., & Singh, A. N. (2020). Odysseys of agriculture: Current challenges and forthcoming prospects. Computers and Electronics in Agriculture 171. doi:10.1016/j.compag.2020.105328.
Palaparthy, V. S., Baghini, M. S., & Singh, D. N. (2013). Review of polymer-based sensors for agriculture-related applications. Emerging Materials Research 2(4); 166-180. doi:10.1680/emr.13.00010.
Sharma, N., Pant, B. D., & Mathur, J. (2019). MEMS devices used in agriculture – A review. Journal of Biosensors & Bioelectronics 10(1). doi:10.4172/2155-210.1000267.