Scientists have developed a soil moisture sensor to optimize irrigation technology. In this respect informs Press service of King Abdullah University of Science and Technology.
Water is a scarce resource for many southern countries, especially if it is required for irrigation. Plants need a certain level of soil moisture to grow, and excess moisture is simply evaporated or absorbed without any benefit, even if it does not harm growth. For metered irrigation, you must have an instrument that measures soil moisture.
Saudi scientists led by Mohamed Eddaudi decided to make sensors based on a metal-organic framework (MOF). MOFs are highly porous synthetic materials with a reticulated internal structure that can be adapted to accommodate certain small molecules, including water. “Because of their modular porous structure and simplicity, MOFs are excellent materials for making sensors,” the scientists explain.
The selection of the MOF type for these purposes was based on their hydrolytic stability, water capacity and water absorption. “We investigated several different MOFs, including the highly porous Cr-soc-MOF-1 developed at our university that can absorb twice its own weight in water,” explains one of the authors.
The team applied the MOCs to an inexpensive interdigitated microsensor that can be produced using inkjet printing or laser etching. When the assembly was immersed in moist soil, the air in the MOC was replaced by water, which changed the electrical capacitance. In contrast, the change in capacitance was recorded by the electrodes and the connected chip.
The device has been tested in clay and loamy sandy soil, which can vary significantly in texture and water holding capacity. “The soil moisture sensor coated with Cr-soc-MOF-1 showed the highest sensitivity – about 450% in clay soil, with a response time of about 500 seconds,” the scientists wrote.
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