Porous Silicon Interferometric Sensors for the Detection of NerveAgent Mimics Using Various Light Sources

Abstract

Various detection methods using nanostructured materials, such as distributed Bragg reflectors (DBRs), for sensing G-type nerve agent mimics have been developed. For DBRs, the versatile porous silicon (PSi) is prepared by electrochemical etching through applied square current waveform. The manufactured DBR exhibits unique optical properties providing the reflection of a specific wavelength in the optical reflectivity spectrum. The detection methods involve the shift of DBR in the reflectivity spectra under exposure to vapors of nerve agent mimics. Rapid detection has been achieved within 5 sec, in situ, and has been observed through the red-shift of the reflection peak caused by an increase in the refractive indices in PSi. Real-time detection for the nerve agent gases indicates that the measurement is reversible. The detection efficiency for nerve agent mimics is also increased when a light-emitting diode (LED, λem = 520 nm) or laser (λem = 530 nm) is used as an incident light source instead of a tungsten-halogen lamp.