Compact Mid-Infrared Gas Sensing Enabled by an All-Metamaterial Design

Abstract

The miniaturization of mid-infrared optical gas sensors has great potential to make the “fingerprint region” between 2 and 10 μm accessible to a variety of cost-sensitive applications ranging from medical technology to atmospheric sensing. Here we demonstrate a gas sensor concept that achieves a 30-fold reduction in absorption volume compared to conventional gas sensors by using plasmonic metamaterials as on-chip optical filters. Integrating metamaterials into both the emitter and the detector cascades their individual filter functions, yielding a narrowband spectral response tailored to the absorption band of interest, here CO2. Simultaneously, the metamaterials’ angle-independence is maintained, enabling an optically efficient, millimeter-scale cavity. With a CO2 sensitivity of 22.4 ± 0.5 ppm·Hz–0.5, the electrically driven prototype already performs at par with much larger commercial devices while consuming 80% less energy per measurement. The all-metamaterial sensing concept offers a path toward more compact and energy-efficient mid-infrared gas sensors without trade-offs in sensitivity or robustness.

Tunable absorber embedded with GST mediums and trilayer graphene strip microheaters

“…Within the context, it is worth mentioning that the red-shifts in absorption peak are linearly scaled for a larger GST layer thickness. Since most of the environmental gas sensors operate in the mid-IR regime, this property remains desirable for designing tunable optical gas sensors 51 .…”

Recent advances in cellulose-based membranes for their sensing applications

“…Similarly, electrochemical sensors have the advantages of accuracy, reliability, rapidity and high sensitivity (Wang et al 2020a , b ). However, the optical sensors are based on the reactions between the measured gas and the sensitive layer, which result in changes of absorbance, fluorescence and color (Lochbaum et al 2020 ).…”

Deterministic Inverse Design of Lithography-Free, Wavelength-Selective Tamm Plasmon Thermal Emitters

“…The inverse design protocol is based on stochastic gradient descent (SGD) that allows for the individual layer thicknesses of the DBR, as well as the carrier density (thus the dielectric function) of CdO to be optimized efficiently (minutes on a consumer-grade desktop) with deterministic design capabilities. Experimentally, we realize several such inversely designed TPP-WS-EMs targeting narrow-band thermal emission at singleor dual-frequencies for various applications, including filterless nondispersive infrared sensing (NDIR 3,18,19 ) and high-Q emitters in the long-and mid-wave infrared (LWIR, MWIR), with all structures exhibiting excellent agreement between experiments and simulations. Furthermore, we illustrate precise spectral control of CdO-based TPP-WS-EMs by matching frequencies, lineshapes and amplitudes of arbitrarily shaped spectra across the entire spectral range from the LWIR to telecommunication bands (1550 nm), including the ability to individually define the frequency and Q-factors (27 -10,127).…”