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In this study, the sensing properties of an amorphous indium gallium zinc oxide (a-IGZO) thin film at ozone concentrations from 500 to 5 ppm were investigated. The a-IGZO thin film showed very good reproducibility and stability over three test cycles. The ozone concentration of 60–70 ppb also showed a good response. The resistance change (ΔR) and sensitivity (S) were linearly dependent on the ozone concentration. The response time (T90-res), recovery time (T90-rec), and time constant (τ) showed first-order exponential decay with increasing ozone concentration. The resistance–time curve shows that the maximum resistance change rate (dRg/dt) is proportional to the ozone concentration during the adsorption. The results also show that it is better to sense rapidly and stably at a low ozone concentration using a high light intensity. The ozone concentration can be derived from the resistance change, sensitivity, response time, time constant (τ), and first derivative function of resistance. However, the time of the first derivative function of resistance is shorter than other parameters. The results show that a-IGZO thin films and the first-order differentiation method are promising candidates for use as ozone sensors for practical applications.

This study proposes a magnetic biochip that uses surface-enhanced Raman scattering (SERS) for antigen detection. The biochip was a sandwich structure containing alternating layers of gold and magnetic Fe 2 O 3 nanoparticles. Both single (Au/Fe 2 O 3 /Au) and multilayer (Au/Fe 2 O 3 /Au/Fe 2 O 3 /Au) chips containing Fe 2 O 3 nanoparticles were fabricated to detect bovine serum albumin (BSA). The single-layer chip detected the BSA antigen at a signal-to-noise ratio (SNR) of 5.0. Peaks detected between 1000 and 1500 cm −1 corresponded to various carbon chains. With more Fe 2 O 3 layers, bond resonance was enhanced via the Hall effect. The distribution of electromagnetic field enhancement was determined via SERS. The signal from the single-layer chip containing Au nanoparticles was measured in an external magnetic field. Maximum signal strength was recorded in a field strength of 12.5 gauss. We observed peaks due to other carbon–hydrogen molecules in a 62.5-gauss field. The magnetic field could improve the resolution and selectivity of sample observations.

A highly sensitive array of two-dimensional (2D) WSe2 nanosheets integrated with zero-dimensional (0D) SnS quantum dots was synthesized by combining liquid-phase exfoliation and wet chemical synthesis methods. The characterization results of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) revealed the formation of WSe2/SnS heterostructures, which enable a cyclic and reproducible high gas sensing response. The role allocation of SnS on WSe2 was verified by using density functional theory (DFT) calculations. The result indicates that the top alignment of SnS and the bottom layer of WSe2 act as a gas adsorption layer and carrier conduction layer, respectively. The charge interactions of the heterostructures were systematically explored by monitoring changes in the transferred characteristics at room temperature (27 °C) after introducing 25–100 ppb NO2. The highest sensing response of WSe2/SnS heterostructures toward the NO2 gas was found to be 1.08 at 25 ppb with a LOD of 10.6 ppb. The experimental and simulation results revealed that the charge transfer across the active sites increased after incorporating SnS in the WSe2. The sensing results showed an abrupt and reliable gas response under periodic NO2 gas injection unambiguously achieved by such heterostructures. The sensor also exhibited satisfactory stability and accuracy in selectivity and is not affected by humidity at room temperature. DFT calculations were also used to explain the sensing mechanism and heterojunction for such nanocomposites.