Paper Title
NEW TRENDS ON SENSORS FOR NPK NUTRIENT MEASUREMENTS: A REVIEW

Abstract
Abstract - This paper presents a review of articles that address the development of nitrogen, phosphorus and potassium (NPK) sensors published in the literature between 2015 and January 2021. This review was carried out in order to encompass studies that use different techniques and point out future perspectives area, these being the main contributions of this article. The research included works published in the IEEE Xplore, Web of Science and Science Direct databases. Each work that referred to NPK detection techniques through the use of sensors was analyzed individually to identify its objective, methodology and results. Based on the analysis of selected works, several of these proved useful for NPK sensing. However, there are certain aspects that still require attention, such as increasing the accuracy of sensors and the development of more versatile sensors, which directly perform NPK sensing in both liquid and solid media. Finally, through this review, it can be stated that more research is needed for the development of NPK detection techniques, as well as for the improvement of the developed sensors. Keywords - NPK, Sensor, Revision