Detection of G-Type Nerve Agent Simulants Based on a Double Reflection DBR Porous Silicon Interferometer

Abstract

Distributed Bragg re ector (DBR) porous silicon (PSi) chips with two re ection peaks were fabricated by electrochemical etching in an aqueous ethanolic HF solution and were used to detect of chemical nerve agent simulants. Dimethyl methylphosphonate (DMMP) is a simulant for G-type nerve agents. The manufactured DBR PSi chips exhibit two sharp photonic bands, 560 and 717 nm, with narrow full widths at half maximum (FWHM) of 15 and 20 nm, respectively. The detection method involved the shift of the DBR re ection peaks in the re ectivity spectra under exposure to vapors of the analyte. Rapid detection was achieved in few seconds in situ and the observed red shift of the DBR peaks resulted from an increase in the refractive indices in DBR PSi. When the DBR PSi chips were exposed to vapor of DMMP, the two re ection peaks from DBR PSi were red-shifted by 22 and 32 nm, respectively. Real-time detection for the stimulant indicated that the detection measurements were reversible. Detection of other analytes, such as triethyl phosphate (TEP) and diethyl ethylphosphonate (DEEP), has been also achieved.