Experimental detection of chlorpyrifos by MoS2 coated planar polymer waveguide sensor utilizing common path interferometric principle

Abstract

A common path Mach-Zehnder interferometer is fabricated using a planer polymer waveguide having MoS2 as an adlayer for chlorpyrifos detection. The dispersion characteristic and cutoff condition of proposed waveguide are obtained theoretically and hence the cutoff film thickness is optimized to get TE0 and TM0 propagating modes. Variations between the phase shift of propagating modes with the concentration of pure chlorpyrifos and its commercial sample are obtained. A good linear variation between phase shift and concentration of chlorpyrifos is obtained in our fabricated waveguide for all considered temperatures. The obtained maximum sensitivity, minimum limit of detection, and limit of quantification of chlorpyrifos are 5.66 degree/μM, 1.57 μM, and 5.24 μM respectively, at 45° C. The capability of the fabricated sensor to generate distinct response for a pure and commercial sample of chlorpyrifos at different concentration and temperature were confirmed by principal component analysis. Since the response of sensor is better for commercial samples at a lower temperature, therefore it is recommended that the concentration of chlorpyrifos in commercial samples should be measured at low temperatures.