INGENIOUS Sensor Differentiates BTX Gases Without Pre-filtering

The joint EU-Russian Innovative nanostructured optochemical sensors (INGENIOUS) project has demonstrated a new ultrasensitive sensor that detects and differentiates benzene, toluene and xylene gases. Because the new sensor can detect the gases at low concentrations and without pre-filtering, it could enable smaller, cheaper and more portable systems for monitoring these gases.

Benzene, toluene and xylene – known as BTX gases – are industrially important products particularly in the petrochemical industry. However, they also pose environmental, health and explosion risks. For example, exposure to benzene is known to increase the risk of cancer, and its effects are cumulative – building up in the body over time. Meanwhile, the less toxic toluene has been linked to “sick building syndrome.” Hence exposure to all three BTX gases is strictly regulated, with particularly low limits for benzene.

Applying these regulations and protecting people from the dangers of BTX gases requires monitoring systems capable of detecting the gases at very low concentrations. To date, this has required gas mixtures to be pre-filtered – making monitoring systems bulky and expensive.

The INGENIOUS project was launched in 2009 to address this issue. It has developed several cutting-edge technologies to push down the detection limits for BTX gases. These include the development of a novel fluorescent compound. This fluorophore forms a reversible complex with the BTX gases, fluorescing at different wavelengths accordingly. The color of the light emitted indicates the gases present, while the intensity reflects the concentration.

To create a solid-state sensor based on this concept, the INGENIOUS team integrated fluorophore-doped materials into a plastic waveguide a few microns thick on foils with LEDs and photodiodes. A demonstrator was shown to be capable of the reversible detection of toluene and xylene at concentrations down to 0.25 ppm, and benzene at concentrations as low as 0.5 ppm without pre-filtering.

Response and recovery times for the detection of all three gases were of the order of a few minutes. Moreover, the demonstrator was able to differentiate BTX gases in the presence of other volatile organic compounds (VOCs) such as hexane and ethanol, which are commonly found in the environments where BTX gas detection is required. While further development and validation of the sensor is still required, the relative simplicity and limited cost of the system could enable its widespread use and enhanced safety for the groups at risk of BTX exposure.

About INGENIOUS
Now officially closed, the INGENIOUS project was a joint EU-Russian initiative that received funding under the EU’s Seventh Framework Programme (FP7). The consortium comprised:
• Holst Centre, the Netherlands
• University of Vigo, Spain
• University of Aarhus, Denmark
• Central Institute for Labor Protection – National Research Institute, Poland
• Russian Academy of Science
• Photochemical Centre
• N. S. Enikolopov Institute of Synthetic Polymeric Materials
• Institute of Macromolecular Compounds
• Institute for Physics of Microstructures