TNT Vapor Detection Based on a Lab-on-a-Fiber: Achieving a Millimeter-Scale Sensing Element on Fiber

Abstract

In this paper, we discuss in detail the lab-on-a-fiber (LOF) concept that we proposed earlier (Ma et al., Proc. 4th Eur. Workshop Opt. Fiber Sens., 2010, vol. 7653, PP. 76531E-76531E-4), and present a specific example of this platform intended for trace vapor TNT detection. We show how we arrive at the current LOF design by examining the performance, technical difficulties, and complexities of various possible architectures. In the design solution adopted in our example, the sensing section occupies a space measuring only 1.6 1.6 0.8 mm, but contains several optical and chemical components/functions including a transmission/reflection mirror and TNT sensory film coated on a segment of the side wall of the fiber core. The fiber itself thus serves as the film substrate and when coated with the film becomes an evanescent-wave form fluorescent emission power collector. Its tiny dimensions notwithstanding, the LOF performs several simultaneous functions, including power density tuning and stray excitation light blocking. In addition, this LOF platform features ease of system construction and polymer film application. We demonstrate its fast response to TNT vapor, in the form of a 29% signal drop after 10 s of exposure.Index Terms-Fluorescence spectroscopy, optical fiber transducers, thin films, TNT explosive detection. are with the Centre de recherche en photonique, Département d'informatique et d'ingénierie,Université du Québec en Outaouais,

Fiber-Optic Sensors for Explosives Detection

“…For example, a FOS with a mini sensing element directly attached to the fiber has much more to offer in terms of real applications than its bulkier counterparts. In recognition of this fact, we have proposed the lab-on-a-fiber (LOF) concept [1][2][3] as a specific category restricted to FOSs featuring millimeter-scale sensing elements. One or more regular laboratory functions or components could be downsized to fit into the tiny space of an LOF to meet the needs of a specific application.…”