DBR porous silicon chip을 이용한 화학신경제 탐지

Abstract

Recently, organophosphorus nerve agents have been a matter of international concern. 'Nerve agent' or 'nerve gas' represents a generic name for a class of highly toxic compounds. Some organophosphorus compounds (e.g., sarin, soman, tabun, DFP, organophophorus surrogates) displaying extremely toxic activity are widely used as chemical nerve agent weapons and pesticide toxins. Many studies have been done for determination and safe destruction of several nerve agents. Nevertheless, the best way is under process. Here, we discovered the easy way to find nerve agents using the DBR(Distributed Bragg Reflectos) porous silicon chip and fabricated nerve agents vapor sensing device. DBR PSi were prepared by an electrochemical etch of P^(++)-type silicon wafer of resistivity between 0.1mcm with square wave current density, resulting two different refractive indices. Etched DBR PSi samples exhibit different kinds of pores and depths. We are able to control the pore size and depth from a few nanometer to several micron by changing the variety of parameters such as etch current, etch time, and the concentration of HF solution. Optical characteristics of DBR PSi were investigated by Ocean Optics 2000 spectrometer. DBR PSi samples have been shown unique optical properties, providing the reflection of specific wavelength in the optical reflectivity spectrum. Thus, the existence of nerve agents by reading of the shifts of reflection wavelength could be easily recognized in the reflectivity spectrum. For instance, when the surface of DBR PSi has been derivatized with copper(Ⅱ)-TMEDA catalyst, organophosphorus surrogates(DMMP, DEEP, TEP) are ready to adsorb though coordination bonding between the oxygen of phosphorous and catalyst of the surface of PSi. When DBR PSi chips are exposed to the vapor of organophosphorus, the reflectivity spectra exhibit a red shift in the reflectivity, indicating that the pore layer of DBR PSi chips filled with organophosphorus vapors affects the refractive indice. Also, we have fabricated simple and portable sensing device, which are able to detect the chemical nerve agents. Optical changes in the presence of chemical nerve agents are converted to a digital readout as a signal output.