Chemical sensor based on the colorimetric response of porous silicon photonic crystal

Abstract

In this article, the authors performed computer simulations and experimentally investigated the application of the colorimetric approach based on CIE1931 color space for characterization of the optical response of porous silicon (PS) based photonic crystals (PC). The colorimetric parameters as dominant wavelength (λdom) and excitation purity (EP) were determined and compared with conventional PC parameters as Bragg peak position λ0 and FWHM. The colorimetric parameters were obtained for PC with different sets of porosity values of bi-layers and the position of Bragg peak λ0(air). The PS sensor structures were fabricated by the method of electrochemical anodization of Si wafer. The colorimetric sensitivity of the PC sensors is higher for structure with smaller refractive indexes. Colorimetric parameters characterize the modification of the entire complex spectrum of the optical sensor as opposed to the conventional parameter as the Bragg peak position. The time dependences of colorimetric parameters on PC parameters during adsorption/desorption of ethanol are determined. The colorimetric approach for sensor characterization is preferable to develop the rapid not dispersive sensor systems as artificial tongue/nose with coordinate-dependent parameters of the spectrum.