A sub-ppbv-level Acetone and Ethanol Quantum Cascade Laser Based Photoacoustic Sensor – Characterization and Multi-Component Spectra Recording in Synthetic Breath

An inexpensive UV-LED photoacoustic based real-time sensor-system detecting exhaled trace-acetone

“…The UV acetone sensor can basically be divided into two parts, i.e., the optical system and the photoacoustic cell which is connected to the gas flow. By means of a magnetic flange and dowel pins, the optics can be separated from the measuring cell in a modular way, allowing to connect our standard measuring cell (see [11] , [12] , [31] ) to the light source in a simple and reproducible way. The UV-LED (a) already incorporates a hemispherical lens to reduce the numerical aperture.…”

“…Moreover, Kidavu et al applied an UV laser, a Mid-IR QCL and a THz source yielding acetone detection limits of 5.05 ppbV, 7.92 ppbV and 15.3 pptV using a Helmholtz photoacoustic cell, respectively [30] . Our group recently achieved a sub-ppbV detection limit of 0.25 ppbV by applying a lock-in time constant of 10 s at laboratory conditions with a QCL-PAS setup at 8.26 µm [31] . As a cost-effective alternative, Weigl et al developed a measurement system based on a modulated UV LED with a limit of detection (LoD) (3σ) of 20 ppbV under controlled laboratory conditions [12] .…”