INTRODUCTION Recently developed prototypes of zirconium dioxide and NASICON-based micro solid-state electrolyte oxygen (O2) and carbon dioxide (CO2) sensors were tested for their potential suitability in rebreathers. The O2 sensor has a quasi-indefinite lifetime, whilst that of the CO2 sensor is approximately 700 h. This is a preliminary report of a new technological application. METHODS The ...

Understanding of the processes that control CO2 concentrations in the aquatic environment has been hampered by the absence of a direct method to make continuous measurements over both shortand long-term time intervals. We describe an in situ method in which a non-dispersive infrared (NDIR) sensor is enclosed in a water impermeable, gas permeable polytetrafluoroethylene (PTFE) membrane and deplo...

Introduction Previously we proposed construction of a miniaturized metabolic monitor that could be taken aboard the space station to monitor the physiological response of the body in a microgravity environment. The prototype consisted of an on airway non-dispersive infrared (NDIR) CO2 sensor and a luminescencequenching O2 sensor to measure gas concentrations, and differential pressure ports to ...

We report a prototype CO2 gas sensor based on a simple blackbody infrared source and a spectrally narrow quantum cascade detector (QCD). The detector absorption spectrum is centered at 2260 cm−1 (4.4 μm) and has a full width at half maximum of 200 cm−1 (25 meV). It covers strong absorption bands of two spectrally overlapping CO2 isotopomers, namely the P-branch of CO2 and the R-branch of CO2. A...

Measuring gases for environmental monitoring is a demanding task that requires long periods of observation and large numbers of sensors. Wireless Sensor Networks (WSNs) and Unmanned Aerial Vehicles (UAVs) currently represent the best alternative to monitor large, remote, and difficult access areas, as these technologies have the possibility of carrying specialized gas sensing systems. This pape...

This publication reports the derivation and the implementation of a simulation model that describes non-resonant photoacoustic gas sensors. The photoacoustic effect is modelled in detail for the successive steps of radiation emission, stimulation of molecules, collisional relaxation processes and finally the pressure formation in a closed gas cell. The photoacoustic effect offers great potentia...

A series of SnO2-ZnO composite nanostructured (thin) films with different amounts of SnO2 (from 0 to 50 wt %) was prepared and deposited on a miniaturized porous alumina transducer using the sol-gel and dip coating method. The transducer, developed by our research group, contains Au interdigital electrodes on one side and a Pt heater on the other side. The sensing films were characterized using...

A versatile gas sensor for use in gravitational studies and/or long-term monitoring of biological systems in space is described. The sensor combines two diode lasers in a compact, low power package for quantitative, simultaneous measurements of oxygen, carbon dioxide and potentially, water vapor. Wavelength modulation spectroscopy(WMS) combined with digital signal processor (DSP) control allows...

The sensing of carbon dioxide (CO2) at room temperature, which has potential applications in environmental monitoring, healthcare, mining, biotechnology, food industry, etc., is a challenge for the scientific community due to the relative inertness of CO2. Here, we propose a novel gas sensor based on clad-etched Fiber Bragg Grating (FBG) with polyallylamine-amino-carbon nanotube coated on the s...

This work describes the implementation and the modeling of an infrared gas sensor with pulse delta-sigma sensing architecture. Beyond the conventional technique of constant periodic heating of infrared light source, our proposed delta-sigma architecture with closed-loop feedback system is built with the hybrid combination of a CO2 infrared sensor with a specific wavelength filter, an infrared M...