Development of a microchip metal ion sensor using dinitro-azocalix[4]azacrown

A microchip metal ion sensor based on absorption of a novel 1,3-alternate calix[4]azacrown having a dinitro-azo-chromophoric pendent group, which was synthesized in this group, was manufactured and its performance was discussed. The microchip optical sensor was composed of light emitting diode (LED, 516.6 nm peak max.) as a light source, photodiode detector, and polydimethyl siloxane (PDMS) microchannel copied from a master of Si wafer. It turns out that dinitro-azocalix[4]azacrown (DAC) can make a complex with various metal ions, such as Na+, Ca2+, Cu2+, and Fe2+, based on the fundamental study of spectrochemical properties for optical sensing. The absorption signal was stable and dependent upon concentration of metal ions. Limit of detection for Na+ was obtained to be 78.4 ng/mL with relative standard deviation of 2.24%.