Optical Fiber Sensor for Plant Nutrients

The problem: Nutrient concentration has a direct effect on the yield and quality of plants. However, despite their importance, they are frequently over applied and, if their concentration is thought to be incorrect, they are discarded into the environment and replaced with a new solution. This leads to nutrient waste and widespread environmental contamination of aquatic, ground and drinking water that causes blooms of harmful algae that, in turn, produce highly potent toxins. The opportunity: Instrumentation capable of determining the concentration of nutrients in water is either costly, unreliable, inconvenient to use or does not have the capability to determine the concentration of specific nutrients. Project Objectives: It is the objective of this project to develop a rugged, compact, inexpensive and yet easy to use optical fiber sensor that uses lab-on-a-fiber concept and microfluidic volumes of water samples. This is a unique multi point/multi parameter optical fiber sensor that can pack at least 20 sensing points for every 10 cm of optical fiber. Due to its multi point capability, it is highly accurate and specific as it is capable of making multiple independent measurements of same or different nutrients, respectively. Description of the effort: During this grant, the optical fiber sensor demonstrated in Phase I will further improved. Using S & ST's unique side illumination technique of an optical fiber, a multi pronged approach will be used to achieve the desired device. Fluorescent, absorption, colorimetric and scattering based techniques will be tested. Both active and passive optical fiber sensors will be used: the first requires a sensitive coating for the targeted parameter, the second requires no sensitive coating at all but can use spectroscopic techniques that will be adapted to the proposed device. The anticipated results are a low cost optical fiber sensor that is rugged, easy to use and that can make multi parametric measurements at different points along the fiber. This device will find applications in hydroponics crop production, as a monitoring device to determine the soil, the environment and drinking water conditions.