Development of a chlorophyll sensor based on absorbance and fluorescence measurers

Abstract

An optical chlorophyll sensor has been developed by employing its unique light absorption and fluorescence properties . Characteristic absorption peaks of chlorophyll a and b occur at 430 nm and 453 nm in blue region and at 665 nm and 642 nm in red region respectively and fluorescence emission peaks occur at 680 nm and 750 nm. LEDs with peak emission wavelength at 405 nm, 435 nm, 525 nm and 680 nm were used as wavelength selective light sources and Hamamatsu s5972 photodiode together with optical filters ( 5 40AESP short pass and 670AF30 band pass filters ) were used as detectors. It is found that there is a good l inear relationship between the chlorophyll concentration (in arbitrary units) and the natural logarithm of the blue and red absorption intensities (