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Here we report a simple approach to increase the stability performance of all-solid-state electrochemical sensors by improving the interfacial bonding between the ion selective membrane and electrode through cold atmospheric plasma surface treatment.

The problematic combination of a rising prevalence of skin and soft tissue infections and the growing rate of life-threatening antibiotic resistant infections presents an urgent, unmet need for the healthcare industry. These evolutionary resistances originate from mutations in the bacterial cell walls which prevent effective diffusion of antibiotics. Gram-negative bacteria are of special consideration due to the natural resistance to many common antibiotics due to the unique bilayer structure of the cell wall. The system developed here provides one solution to this problem through a wearable therapy that delivers and utilizes gaseous ozone as an adjunct therapy with topical antibiotics through a novel dressing with drug-eluting nanofibers (NFs). This technology drastically increases the sensitivity of Gram-negative bacteria to common antibiotics by using oxidative ozone to bypass resistances created by the bacterial cell wall. To enable simple and effective application of adjunct therapy, ozone delivery and topical antibiotics have been integrated into a single application patch. The drug delivery NFs are generated via electrospinning in a fast-dissolve PVA mat without inducing decreasing gas permeability of the dressing. A systematic study found ozone generation at 4 mg/h provided optimal ozone levels for high antimicrobial performance with minimal cytotoxicity. This ozone treatment was used with adjunct therapy delivered by the system in vitro. Results showed complete eradication of Gram-negative bacteria with ozone and antibiotics typically used only for Gram-positive bacteria, which showed the strength of ozone as an enabling adjunct treatment option to sensitize bacteria strains to otherwise ineffective antibiotics. Furthermore, the treatment is shown through biocompatibility testing to exhibit no cytotoxic effect on human fibroblast cells.

The demand for the development of chemiresistive sensors for the detection of acetaldehyde has been rapidly increasing, as its concentration needs to be continuously monitored in many industries. Also, exposure to acetaldehyde beyond a permissible limit leads to various health complications including nausea, irritation, headache, and respiratory tract complications. In this context, acetaldehyde-sensing properties of tungsten-doped ZnO thin films deposited using the Successive Ionic Layer Adsorption and Reaction (SILAR) technique by varying the tungsten-dopant concentration from 2 to 10 mM are reported. XRD patterns of both the undoped and tungsten-doped ZnO films divulge the formation of hexagonal wurtzite structure with a preferential plane orientation of (0 0 2). Formation of clustered tiny nanobeads composed of spherical nanograins was observed for undoped ZnO thin film, and the formation of spherical nanoaggregates with dimensions less than ~ 1 μm was observed for the films deposited with tungsten concentrations of 2–8 mM. At 10 mM, formation of homogeneously distributed elongated nanobead-like morphology was observed. Room-temperature vapor-sensing properties of undoped and W-doped ZnO thin films were investigated. Undoped ZnO thin film was selective towards ammonia, whereas the doped ZnO thin films showed a better response towards acetaldehyde. In particular, the film deposited at 10 mM W-doped ZnO exhibited a sensing response of 947 towards 100 ppm of acetaldehyde. The response and recovery times were found to be 53 and 5 s, respectively, with a minimum detection limit of 10 ppm.

Over the past decades, many materials like metal oxides, conducting polymers, carbon nanotubes, 2D materials, graphene, zeolites and porous organic frameworks (MOFs and COFs) have been explored for chemo-sensing applications owing to their unique properties. One such 2D material in the center of attraction in recent years is graphitic polymeric carbon nitride, g-CN (so-called g-C3N4). It has emerged as a potential candidate for chemo-sensing applications due to its facile synthesis, physicochemical properties, and tunable electronic structures. Though there are a few reports and reviews available for various other sensing principles of g-C3N4, such as photo-electrochemical, electrochemiluminescence, electrochemical and fluorescence-based ion-sensing and bio-sensing, it is difficult to find a comprehensive review solely on the chemi-resistive gas sensing signatures of g-C3N4. This stood out as our first and foremost inspiration to compile this review by focusing on chemi-resistive sensors reported using g-C3N4 and its composites. In this review, the humidity and VOC sensing applications of g-C3N4 & its composites have been accentuated. A detailed sensing mechanism, along with the specific rationales for selective detection, has been presented. Along with the specific figures of merit of the g-C3N4 based chemo-sensors, a futuristic perspective of carbon nitride-based hybrid materials and key strategies to improve the sensing characteristics are presented. Thus, this progress in the recently booming g-C3N4 and its hybrid-based chemo-sensors paves a way to further fabricate different forms of g-C3N4 based sensors for the challenges ahead in the field of energy and environment, especially IoT based futuristic sensing platforms.

Topical lidocaine patches are commonly used to relieve pain and suffering in various clinical and household settings. Despite its extensive use, excessive skin absorption during numbing or pain reduction procedures can cause systemic toxicity, which can lead to life-threatening conditions. Rapid and reliable monitoring of escalating levels of lidocaine in the blood could help management/prevention of lidocaine overdose and its associated complications. To address this need, here we have developed a disposable point-of-care (POC) diagnostic platform composed of an integrated graphene-based electrochemical sensor with paper-based microfluidics for rapid detection of lidocaine levels in serum and blood samples. The fabrication process takes advantage of advanced, scalable manufacturing techniques, including printing, laser processing, and nondestructive near infrared (NIR) drying. The sensitivity tests of the platform revealed a sensitivity of ∼0.2 μA μM

The growing pervasiveness of opioid-based drugs such as fentanyl and its analogs represent a foremost hazard to the civilian population and burden on the first responders and clinicians. Thus, to enable a rapid and low-cost surveillance system to detect fentanyl in a non-ideal environment, we demonstrate the use of laser-induced nano-porous carbon structures directly onto commercially available polyimide sheets for rapid and cost-effective manufacturing of electrochemical sensors for fentanyl detection. The porous carbon surface instigated by various laser energy densities was analyzed towards morphological, vibrational, and fentanyl sensing properties. The results showed that laser carbonized electrode (LCE) prepared with 31 J/cm

In recent years, there is a massive demand for the development of high-performance sensing technologies to curtail the effect of environmental pollutions. One such primary ecological concern is water pollution, where the major risk factor is associated with the concentrations of the chemical residues (hydrogen peroxide [H2O2]) in drinking water. Keeping this in view, we have demonstrated a non-enzymatic electrochemical probing of H2O2 in water employing microwave-assisted TiO2-ZrO2-HfO2 ternary nanocomposite for the first time. Structural analysis revealed the formation of monoclinic phases of ZrO2 and HfO2 along with anatase phased TiO2. Dynamic sensing characteristics of the TiO2-ZrO2-HfO2 nanocomposite were studied by varying the concentration of H2O2 from 1 to 19 µM where the sensor showed linearity up to 9 µM. The LOD and LOQ of the sensor were found to be 0.32 and 1.06 µM respectively along with the sensitivity of 6.71 $$\mu \mathrm{A}\bullet\upmu {\mathrm{M}}^{-1}$$ . The dominant signal change of Zr4+ ions in the TiO2-ZrO2-HfO2 nanointerface upon interacting with H2O2 has significantly inhibited the Hf4+ ions from taking part in the redox reaction, which refers to the sacrificial behavior. The reaction hierarchy was observed as ZrO2 (Eo = − 1.23 V) > TiO2 (Eo = − 1.15 V [suppressed peak]) > HfO2 (no redox peaks observed sacrificial). The real-time recovery study was carried out using the tap water, field water, and urban river water samples with repeatable and reproducible characteristics. Thus, our study provokes a new dimension in exploring many ternary nanointerfaces in the near future for the electrochemical sensing of different analytes.

ZnO thin films were deposited onto the glass substrates using successive ionic layer adsorption and reaction (SILAR) technique by varying the deposition cycles from 25 to 100 in steps of 25 cycles. The effect of deposition cycles on the structural, morphological, optical and electrical properties was investigated and reported. Structural analysis revealed the formation of the hexagonal wurtzite crystal structure of ZnO with the preferential plane orientation of (1 0 0) for all deposition cycles. For the film deposited at 25 cycles alone, we observed the meagre diffraction peak at 2θ = 21.27° corresponds to (1 0 1) plane of the orthorhombic phased zinc sulphate, which indicated the incomplete formation of zinc ammonium complex from the precursor. Morphological analysis revealed the formation of nanorod-like morphology for the deposition cycles of 25 and 50, whereas it was found to be deformed at 75 and 100 cycles. The optical bandgap of the deposited thin films was decreased as a function of deposition cycles. However, at 75 deposition cycles, the bandgap was increased to 3.2468 ± 0.0026 eV, and it could be attributed to the variation in the density of states near the conduction band. The significant variations in the electrical parameters namely, carrier concentration, mobility, electrical resistance as a function of deposition cycles were investigated. The variations in the refractive index and static impedance characteristics as a function of deposition cycles were also studied and reported.

Microwave irradiation technique provides a simple and quick synthesis route for nanomaterials at controlled experimental conditions. In this view, nanostructures of rGO, ZrO2, and rGO–ZrO2 composite were synthesized using microwave synthesis technique. Herein, we experimented the preparation of rGO using optimized conditions using convection mode at 373 K in a commercial microwave oven. Structural properties revealed the formation of mixed phases of the orthorhombic and rhombohedral crystal structure of ZrO2. The preferential plane orientation was found to be in c-axis (002) for rGO–ZrO2 nanocomposite, which revealed the predominance of rGO in the nanocomposite. Morphology of the prepared nanostructures exhibited agglomerated sheets, denser nanograins and randomly aggregated nanosheets for rGO, ZrO2, and mixed nanocomposite respectively. Room temperature gas sensing properties of the prepared nanostructures were investigated and reported. rGO showed responses of 5.3 and 5.2 towards 200 ppm of trimethylamine (TMA) and methanol. ZrO2 nanostructure showed a response of 35 towards 200 ppm of ammonia with response–recovery times of 91 and 6 s.