Viral aerosol transmission of SARS-CoV-2 from simulated human emission in a concert hall.

The dispersion of aerosols was studied experimentally in several concert halls to evaluate their airborne route and thus the risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spreading. For this, a dummy was used that emits simulated human breath containing aerosols (mean diameter of 0.3 μm) and CO, with a horizontal exhalation velocity of v = 2.

Experimental Investigation of Aerosol and CO Dispersion for Evaluation of COVID-19 Infection Risk in a Concert Hall.

The dispersion of small aerosols in a concert hall is experimentally studied for estimating the risk of infection with SARS-CoV-2 during a concert. A mannequin was modified to emit an air stream containing aerosols and CO. The aerosols have a size distribution with a peak diameter (δ) close to 0.

QEPAS sensor for breath analysis: a behavior of pressure.

The measurement of trace gases has increasingly become a key technique in healthcare and other medical applications. Quartz-enhanced photoacoustic spectroscopy (QEPAS) is a suitable method that can provide the required characteristics in such applications for a comparatively low cost and small size. The quantitative detection and a low detection limit are also required by applications.

LED-Absorption-QEPAS Sensor for Biogas Plants.

A new sensor for methane and carbon dioxide concentration measurements in biogas plants is presented. LEDs in the mid infrared spectral region are implemented as low cost light source. The combination of quartz-enhanced photoacoustic spectroscopy with an absorption path leads to a sensor setup suitable for the harsh application environment.

Detection of molecular oxygen at low concentrations using quartz enhanced photoacoustic spectroscopy.

Molecular oxygen is detected at low concentrations using photoacoustic spectroscopy despite its unfavorable photoacoustic properties. The system consists of a seed laser diode, a tapered amplifier and a quartz tuning fork based spectrophone, thus employing quartz enhanced photoacoustic spectroscopy (QEPAS). With this system a detection limit of 13 ppm is reached with a compact and long term stable setup.

Resonant tuning fork detector for THz radiation.

THz-sensing is an emerging technology that would be advantageous for a variety of applications in industry, biology, biochemistry and security, if small and convenient to use sources and detectors would be readily available. However, most of them are bulky, complicate to operate, and need cryogenic cooling. Here we present a new detection scheme that is versatile enough to detect electro-magnetic radiation within the whole spectrum, can be easily applied to the THz-range, and operates at room temperature.

Photonic sensor devices for explosive detection.

For the sensitive online and in situ detection of gaseous species, optical methods are ideally suited. In contrast to chemical analysis, no sample preparation is necessary and therefore spectroscopic methods should be favorable both in respect of a fast signal recovery and economically because no disposal is needed. However, spectroscopic methods are currently not widely used for security applications.

Evanescent field sensors and the implementation of waveguiding nanostructures.

Conventional fiber optic evanescent-field gas sensors are based on a high number of total reflections while the gas is passing the active bare core fiber and of course a suitable laser light source. The use of miniaturized laser sources for sensitive detection of CO(2) in gaseous and water-dissolved phase for environmental monitoring are studied for signal enhancing purposes. Additionally, the fiber optic sensor, consisting of a coiled bare multimode fiber core, was sensitized by an active polymer coating for the detection of explosive TNT.

Resonant tuning fork detector for electromagnetic radiation.

A mechanical quartz microresonator (tuning fork) is used to detect electromagnetic radiation. The detection scheme is based on forces created due to the incident electromagnetic radiation on the piezoelectric tuning fork. A force can be created due to the transfer of the photon momentum of the incident electromagnetic radiation.

In situ and on-line monitoring of CO in an industrial glass furnace by mid-infrared difference-frequency generation laser spectroscopy.

A compact mid-infrared (MIR) laser spectrometer based on difference-frequency generation (DFG) is applied as a portable and sensitive gas sensor for industrial process control and pollutant monitoring. We demonstrate the performance of such a MIR DFG gas sensor by recording the absorption spectra of the carbon monoxide (CO) P(28) absorption line in the atmosphere of a gas-fired glass melting furnace. For a gas temperature of approximately 1100 degrees C, the CO concentration in the recuperator channel is measured to be 400 parts per million.

Fiber-optic evanescent-field laser sensor for in-situ gas diagnostics.

A compact, rugged and portable fiber-optic evanescent-field laser sensor is developed for the detection of gaseous species in harsh environments such as volcano fumaroles or industrial combustion of glass furnaces. The sensor consists of an optical multi-mode fused silica fiber with jacket and cladding removed and the bare fiber core in direct contact with the surrounding molecules. The beam of a single-mode DFB diode laser with an emission wavelength centered at 1.