Synergistic Integration of Chemo‐Resistive and SERS Sensing for Label‐Free Multiplex Gas Detection

Abstract

Practical sensing applications such as real‐time safety alerts and clinical diagnoses require sensor devices to differentiate between various target molecules with high sensitivity and selectivity, yet conventional devices such as oxide‐based chemo‐resistive sensors and metal‐based surface‐enhanced Raman spectroscopy (SERS) sensors usually do not satisfy such requirements. Here, a label‐free, chemo‐resistive/SERS multimodal sensor based on a systematically assembled 3D cross‐point multifunctional nanoarchitecture (3D‐CMA), which has unusually strong enhancements in both “chemo‐resistive” and “SERS” sensing characteristics is introduced. 3D‐CMA combines several sensing mechanisms and sensing elements via 3D integration of semiconducting SnO2 nanowire frameworks and dual‐functioning Au metallic nanoparticles. It is shown that the multimodal sensor can successfully estimate mixed‐gas compositions selectively and quantitatively at the sub‐100 ppm level, even for mixtures of gaseous aromatic compounds (nitrobenzene and toluene) with very similar molecular structures. This is enabled by combined chemo‐resistive and SERS multimodal sensing providing complementary information.

Surface enhanced Raman scattering of adsorbates on Au–CsPbIBr2 perovskite-based nanocomposites: charge-transfer and electromagnetic enhancement

“…Since the sputtered gold nanofilm has a smooth surface and a small specific surface area, the observed SERS enhancement is weak, so the SERS enhancement observed by this method mainly comes from chemical enhancement. According to references with organic–inorganic hybrid perovskite reported previously, 31–33,47–49 it has been pointed out that the enhancement of the perovskite substrate mainly comes from the CT effect between probe molecules and the perovskite substrate, which is similar to the chemical contribution of inorganic semiconductors in SERS enhancement. The band gap, valence band and conduction band of all-inorganic perovskite CsPbIBr 2 were measured by UV-vis and UPS to draw the energy level diagram (Fig.…”

Challenges and Opportunities of Chemiresistors Based on Microelectromechanical Systems for Chemical Olfaction

“…Consequently, sensing signal decreases or drifts from one sensing cycle to the next can be appropriately controlled. More than that, some regular 3D structures with localized surface plasmon resonance (SPR) effects can also greatly improve light-activated carrier transport and enhance the gas-sensing performance by hot electron generation. , …”

“…More than that, some regular 3D structures with localized surface plasmon resonance (SPR) effects can also greatly improve light-activated carrier transport and enhance the gas-sensing performance by hot electron generation. 60,61 Although considerable progress has been made in preparing the elementary building blocks illustrated in Figure 2, remains a great pressure to rationally assemble them into good functionally oriented architectures with locked chemical composition. As such, searching for optimal sensing materials is a multidimensional problem, where many "descriptors" connecting the microscopic parameters (for example, band structure, formation thermodynamic stability, defect energies, or density of states) and macroscopic properties of the materials (for example, operating temperature, charge mobility, or adsorption−desorption capacity) should be known at the same time.…”

Enhanced Surface Plasmon by Clusters in TiO2-Ag Composite

“…Surface plasmon-related observations in nanostructures have recently attracted many researchers due to both the theoretical importance and the wide applications [ 4 ]. In the view of the classic physics [ 5 , 6 ], the coherent movements of the electrons driven by the electromagnetic field of incident light carry significant energy, which can be delivered to their surroundings by the relaxation process, resulting in the local energy enhancement around the nanostructures [ 7 , 8 ].…”