LETI announces protoype of low-cost photo-acoustic sensors for gas detection
Leti, a research institute of CEA Tech, has announced prototype development of highly miniaturized, portable optical sensors for chemical detection of gas.
The next-generation, centimetre-size photo-acoustic sensors are based on mid-infrared photonic integrated circuits (MIR PICs). These silicon PICs, created by integrating optical circuits onto millimetre-size silicon chips, make extremely robust miniature systems, in which discrete components are replaced by on-chip equivalents. This makes them easier to use and reduces their cost dramatically, expected at least by a factor of 10.
Developed by the European Commission’s REDFINCH Project headed by CEA-Leti, the prototype photo acoustic sensors were fabricated on a CMOS line in a miniaturized silicon photo-acoustic cell, which allows extreme integration.
In demonstrations, the sensors match the performance of bulky commercial gas-sensing systems commonly available today. They are targeted at applications such as process gas analysis in refineries, gas leak detection in petrochemical plants and pipelines, and protein analysis in liquids for the dairy industry.
An invited paper on the breakthrough, “Photo-acoustic cell on silicon for mid-infrared QCL-based spectroscopic analysis”, won Best Paper Award at Photonics West 2019.
The sensors aims to consume less than 10W in continuous operation. They can be operated in a slow pulse-burst mode for infrastructure monitoring and when leaks are detected, the pulse frequency of the sensor automatically increases. This keeps average power consumption very low so the sensors can be battery-operated for more than a year or powered by an ambient energy harvester, e.g. a solar cell.
“The big picture is that the miniaturization of photo-acoustic spectroscopy based on quantum cascade lasers (QCLs) is entering the stage of mass production,” said Jean-Guillaume Coutard, an instrumentation engineer at Leti, who coordinate the project.
To develop these chemical sensors, the REDFINCH consortium overcame the challenge of implementing their capabilities in the important mid-infrared region, where many important chemical and biological species have strong absorption fingerprints.
“This allows both the detection and concentration measurement of a wide range of gases, liquids and biomolecules,” Coutard said. “This is crucial for applications such as health monitoring and diagnosis, detection of biological compounds and monitoring of toxic gases.”
“This project is a perfect fit for mirSense’s development roadmap. Our mission is to democratize QCL usage,” said Mathieu Carras, CEO of mirSense, which participated in the project. “mirSense is ready to produce these state-of-the-art integrated QCL-based components and do a similar job on electronics and software to bring the value of this technology to the market.”
The consortium members and contributions include:
• Cork Institute of Technology (Ireland) – PIC design & fabrication, hybrid integration
• Université de Montpellier (France) – Laser growth on Si, photodetector growth
• Technische Universität Wien (Austria) – Liquid spectroscopy, assembly/test of sensors
• mirSense (France) – MIR sensor products, laser module integration
• Argotech a.s. (Czech Republic) Assembly/packaging of PICs
• Fraunhofer IPM (Germany) – Gas spectroscopy, instrument design/assembly
• Endress+Hauser (Germany) Process gas analysis and expertise, testing validation.
