Optical Fiber Sensor for Plant Nutrients

Nutrient concentrations in greenhouse crops have a direct effect on the yield and quality of flowering plants. Nutrients are often applied on a rule of thumb basis and the level of nutrients and salinity "in the bag" is controlled by leaching with the salinity level measured with a salinity sensor in the leachate water. However, specific nutrient measurement is expensive and often requires wet chemistry. Two different approaches have been used so far: Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) and Ion Selective Electrodes (ISE). The ICP method is very sensitive and selective however, it is also expensive: on the order of tens of thousands of dollars. The ISE method is portable and cost effective but suffers from interference from other species, is subjected to electromagnetic interference and requires constant maintenance. It is the purpose of this project to develop a unique, low cost multi point/multi parameter optical fiber sensor to monitor the primary nutrients (nitrate, phosphate and potassium ions), in hydroponics solution. This is a real time single strand optical fiber that has an active cladding sensitive to the targeted species.