Remote and in situ sensing products in chemical reaction using a flexible terahertz pipe waveguide

Borwen You, Ja Yu Lu

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)


The feasibility of remote chemical detection is experimentally demonstrated by using a Teflon pipe as a scanning arm in a continuous-terahertz wave sensing and imaging system. Different tablets with distinct mixed ratios of aluminum and polyethylene powders are well distinguished by measuring the power reflectivities of 0.4 THz wave associated with their distinct terahertz refractive indices. Given its refractive index sensitivity and fast response, the reflective terahertz sensing system can be used to real-time trace and quantitatively analyze the ammonium-chloride aerosols produced by the chemical reaction between hydrochloric acid and ammonia vapors. With a tightly focusing terahertz beam spot, the spatial and concentration distributions of the generated chemical product are successfully mapped out by the 1D scan of the flexible pipe probe. In consideration of the responsitivity, power stability, and focused spot size of the system, its detection limit for the ammonium-chloride aerosol is estimated to be approximately 165 nmol/mm2. The reliable and compact terahertz pipe scan system is potentially suitable for practical applications, such as biomedical or industrial fiber endoscopy.

Original languageEnglish
Pages (from-to)18013-18023
Number of pages11
JournalOptics Express
Issue number16
Publication statusPublished - 2016 Aug 8

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics


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