New fluorescent sensors based on Calix[4]arene-biscrown-6 containing an extended courmarin as fluorophore were synthetized and their photophysical studies were characterized. These compounds display intense absorption and emission spectra in visible region thanks to an extension of the coumarin system. The complexation properties of these ligands were reported and the Calix-COU-Benz-CN ligand was shown to be able to selectively detect cesium ion in an organoaquous solvent. Upon addition of cesium, a blue shift in absorption spectra and an enhancement of emission spectra was observed. This ligand was incorporated in a microfludic device for the detection of Cs+ ions and showed detection limit of 1.4 M for these ions.