Development and Optimization of a Mid-Infrared Hollow Waveguide Gas Sensor Combined with a Supported Capillary Membrane Sampler

Abstract

A gas sensor for application in water analysis was developed by combination of a mid-infrared (MIR) hollow waveguide with a Fourier transform infrared (FT-IR) spectrometer and coupling of the hollow waveguide gas sensor module to a supported capillary membrane sampler (SCMS) for continuous liquid-gas extraction. Different hollow waveguides have been characterized in this study for developing an optimized optical configuration. Analysis of industrially relevant compounds has been performed, investigating chlorinated hydrocarbons (CHCs), such as dichloromethane and chloroform, representing highly volatile analytes, and 1,4-dioxane as an example of target compounds with low volatility. The suitability of this spectroscopic IR sensing system for industrial applications is demonstrated under simulated real-world conditions with limits of detection in the ppb (v/v) and ppm (v/v) concentration range for CHCs and 1,4-dioxane, respectively.

Optoelectronic Capillary Sensors in Microfluidic and Point-of-Care Instrumentation

“…with the inner wall surface coated with a reflecting layer of Ag/AgI showed excellent light transmission in mid-infrared range with an attenuation of 0.1 dB/m at 10.6 μm and functioned both as optical waveguides and gas cells. They were used for gas detection in conjunction with SiC globar light sources and FTIR spectrometers down to ranges of ppb for chlorinated hydrocarbons and ppm for 1,4 dioxane [35]. In conjunction with a supported capillary membrane those capillaries were used to detect the concentration of volatile organic compounds in water down to ppm level [36].…”

Midinfrared sensors meet nanotechnology: Trace gas sensing with quantum cascade lasers inside photonic band-gap hollow waveguides

“…Hollow waveguides 11,12 consisting of a glass structural tube coated at the inside with a reflective layer were used as capillary gas cells in many configurations [13][14][15][16][17][18][19] showing moderate improvements in sensitivity and response time compared to other gas sensing techniques, such as open path gas analysis and multipass gas cells. Hollow waveguides 11,12 consisting of a glass structural tube coated at the inside with a reflective layer were used as capillary gas cells in many configurations [13][14][15][16][17][18][19] showing moderate improvements in sensitivity and response time compared to other gas sensing techniques, such as open path gas analysis and multipass gas cells.…”

Peer Reviewed: Mid-IR Fiber-Optic Sensors

“…Figure 2b schematically illustrates that radiation transported inside the waveguide by reflection at the walls (dark gray) interacts with gaseous analytes inside the hollow core of the fiber. Provided there are appropriate gas inlet/outlet modules, volatile analytes present in the gas phase or after liquid/gas extraction are readily detected inside the hollow waveguide capillary (Figure 3b) (28,29). Another strategy for detecting volatile organic compounds in water is based on pre-enrichment from the sample solution directly flowing through an internally polymer-coated hollow waveguide (30,31).…”