Optical Carbon Dioxide Detection in the Visible Down to the Single Digit ppm Range Using Plasmonic Perfect Absorbers

Abstract

To tackle climate change and reduce CO2 emissions, it is important to measure CO2 output precisely. Even though there are many different techniques, no simple and cheap optical method in the visible is available. This work studies plasmonically enhanced optical carbon dioxide sensors in the visible wavelength range. The sensor samples are based on an inert plasmonic perfect absorber, which can be easily and cheaply fabricated by colloidal etching lithography. A CO2-sensitive polyethylenimine (PEI) layer is then spin-coated on top to complete the samples. The samples are examined continuously by microspectroscopy during different CO2 exposures to track spectral changes, particularly the position of the resonance centroid wavelength. The samples exhibit a resonance shift of up to 7 nm, depending on the CO2 concentration and the temperature. The temperature influences the rise time as well as the sensitive concentration range. The concentration dependence of the resonance shift overall follows the shape of a Langmuir isotherm, which includes a nearly linear relation at lower concentrations and elevated temperatures and a saturating behavior at higher concentrations and lower temperatures. The results indicate that a sensitivity in the full range from 100 vol % to below 1 ppm can be achieved. The samples degenerate in a dry inert atmosphere in a matter of days but are useable over multiple weeks when exposed to humidity and CO2. The PEI reacts very selectively to CO2, showing no response to CO, NH3, NO2, CH4, H2, and only a very small response to O2. Overall, polyethylenimine is very promising as a CO2-sensitive material for many practical sensing applications over a wide range of concentrations. An adjustment of the temperature is mandatory to control the sensitivity and response time.

Nanophotonic Chiral Sensing: How Does It Actually Work?

“…For the sensing of “nonchiral” material properties, this is already a well-established technique. Applications include the ultrasensitive detection of biomolecules, − gases, , and much more. − In the past decade, a lot of work, both experimental − and theoretical, ,− has been carried out to utilize the benefits of this technique for the detecion of chiral substances. Different resonator designs have been investigated, ranging from plasmonic antennas − ,, to dielectric nanostructures ,,,, or combinations to so-called “helicity-preserving” cavities. ,− Another promising route is using structures that exhibit resonances in the ultraviolet region, − where natural molecules have particularly large κ values.…”

Tuning of Reciprocal Plasmonic Metasurface Resonances by Ultra-Thin Conformal Coatings

“…Metamaterials with perfect absorption have attracted much attention as they allow the design of novel sensors for the detection of trace gasses [12][13][14][15], are used for increasing the efficiency of solar cells [16,17], and are also used as optical switches [18,19], for instance. In order to achieve perfect absorption, metamaterial designs that rely on heterostructures have shown promising results.…”

“…In order to achieve perfect absorption, metamaterial designs that rely on heterostructures have shown promising results. These materials are composed of multiple, stratified constituents [9,10,[13][14][15][20][21][22][23][24][25][26][27][28].…”

Phonon-Enhanced Mid-Infrared CO2 Gas Sensing Using Boron Nitride Nanoresonators

“…For instance, thin films of polyethylenimine (PEI) polymer were shown to selectively adsorb CO 2 and could be regenerated through thermal desorption . Efficient optical CO 2 detection was demonstrated with PEI deposited on resonant nanostructures surfaces such as metal metasurfaces, , graphene nanostructures, and all-dielectric photonic crystal slab …”

“…For instance, thin films of polyethylenimine (PEI) polymer were shown to selectively adsorb CO 2 and could be regenerated through thermal desorption. 21 Efficient optical CO 2 detection was demonstrated with PEI deposited on resonant nanostructures surfaces such as metal metasurfaces, 22,23 graphene nanostructures, 24 and all-dielectric photonic crystal slab. 25 In this work, we demonstrate phonon-enhanced mid-IR gas sensing using monoisotopic hBN nanoribbon arrays functionalized with a thin CO 2 -adsorbing PEI layer.…”