Events such as the Port of Rizhao gas plant explosion in China that killed 173 people and injured hundreds of others in 2015; the explosion at the U.S.’s third largest refinery in Texas City, Texas, in 2005; and the Buncefield oil storage explosion in Hertfordshire, England, in 2005 can devastate communities, leaving a mark for generations.
By using autonomous patrolling robots, photonic integrated circuits (PICs), and photoacoustic gas sensors, European researchers are using light and sound together to prevent similar mishaps.
The REDFINCH (mid-infraRED Fully INtegrated CHemical sensors) team is fitting autonomous robots with tiny chemical sensors that listen to the sounds coming off gases to instantly detect the sensitivity of the wavelength fingerprint of a gas.
The consortium is made up of eight research institutes and companies: CEA-Leti, Cork Institute of Technology, the University of Montpellier, mirSense, Argotech, Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung, Endress+Hauser Process Solutions GmbH, and Technische Universität Wien.
REDFINCH project dissemination manager David Williams told Photonics Media that current gas detection technology using IR systems is often large, bulky, and slow, and detectable wavelengths are restricted.
“For onsite process gas analysis, gas chromatographs are still the most commonly used technique. These can take up to eight minutes to complete each measurement,” he said. “The REDFINCH sensors can return results in milliseconds. And due to their compact size and relatively low cost, it is possible to deploy more of them at different points in the plant. This provides faster, more comprehensive monitoring of the process, and allows more efficient control of process parameters.”
The REDFINCH team is combining PICs and microphotoacoustic sensors as part of a wireless network to continuously monitor pipelines. The devices can identify petroleum, hydrogen sulphide, and a number of toxic gases before alerting operatives in an oil rig or chemical plant.
The ultimate target for REDFINCH is three different demonstrator PICs.
“The material systems will include quantum cascade and intraband cascade lasers bonded onto the silicon substrate, GaSb-based lasers grown directly on silicon, and hybrid photonic crystal lasers using patterned nanostructures,” said Williams. “The lasers will be coupled into one or a few output waveguides, providing an extremely flexible laser source module for gas-sensing applications.”
Potentially, the REDFINCH product would include up to 30 lasers, and will be capable of selectively tuning across a wide 3- to 8-μm range. The starting basis for this module is a QCL-based product currently offered by REDFINCH partner company mirSense.
“By integrating all the components, such as the laser, the detector, and the sensing chamber all onto one single chip, we reduce the possible points of failure and more importantly, the ‘noise’ ratio to improve the sensing capabilities.”
The MIR REDFINCH devices are designed to be, as much as possible, compatible with CMOS production technologies, meaning that they can be scaled up to volume production with a minimum of difficulty.
Photonics techniques are inherently noninvasive and particularly attractive for sensing applications. Essentially they just shine a light through the gas, eliminating danger of contamination of the gas or liquid being measured.
The REDFINCH techniques and devices could potentially be used in a huge range of sensor applications down the road, including environmental monitoring, drone-mounted sensing, automotive sensing and emissions monitoring, and in health care through breath analysis.