Reduced Graphene Oxide/Polydimethylsiloxane as an Over-Coating Layer on Quartz Tuning Fork for Sensitive Light-Induced Thermoelastic Spectroscopy

A novel near-infrared light-induced thermoelastic spectroscopy (LITES) based on a multilayer surface-coated quartz tuning fork (QTF) is proposed for gas detection. Thin-film of reduced graphene oxide (rGO) and polydimethylsiloxane (PDMS) is successively coated on the surface of QTF to improve the laser absorption and thermoelastic conversion efficiency, respectively. NH
₃
is selected as the target analyte for the measurements. The experimental results indicate that introducing a thin layer of PDMS-rGO composite allows a maximum gain factor of 8.64 and 5.53 for the signal amplitude and signal-to-noise ratio (SNR), respectively, compared to a commercial standard QTF. A minimum detectable concentration of 8.98 ppmv was obtained, improved by 5.12 times than that of a bare QTF, and a normalized noise equivalent absorption coefficient (NNEA) of
${1.53}\times {10}^{-{9}}\,\text {cm}^{-{1}} \cdot \text {W} \cdot \text {Hz}^{-\text {1/2}}$
was achieved. The results of Allan deviation analysis show that the detection sensitivity reaches 2.63 ppmv when the averaging time is 555 s. The research work and related results have laid a good foundation for trace gas detection by the cost-effective and easy-to-operate infrared sensor.