Search

The current work reports the room temperature sensing of CO2 by growing Si-incorporated TiO2 thin films on Si-substrate with enhanced sensing response. The study suggests that the incorporation of SiO2 in TiO2 lattice can be used to manipulate its defect states which alter the electrical conductivity of TiO2 from n-type to p-type. The TiO2 and Si-incorporated TiO2 thin films are grown on Si-substrate at 250 °C by VLS method. FESEM images confirm the formation of a continuous film and the XRD analysis of such thin films indicates transformation of crystalline anatase TiO2 to amorphous nature upon Si incorporation. The incorporation of Si within TiO2 also results in the formation of oxygen related vacancy states along with the reduction of Ti related vacancies within the TiO2 lattice. Such defect states have been investigated by performing absorption spectroscopy, room temperature PL measurements and XPS analysis. The 50% Si-incorporated TiO2 thin film is observed to provide a sensing response of 198% at 200 sccm CO2 flow rate which is only 2.54% for TiO2 thin film when measured at room temperature with ~ 47% relative humidity. However, such room temperature sensing response decreases with the increase of relative humidity and found to be 73% when the relative humidity is increased to 85%. Furthermore, such Si-incorporated TiO2 sensors exhibit a fast response and recovery time of 5.7 s and 3.6 s, respectively. Therefore, the 50% Si-incorporated TiO2 thin film-based sensors can be efficiently used for room temperature CO2 sensing by utilizing a simple cost-effective fabrication technique. [ABSTRACT FROM AUTHOR]

This work investigates the capabilities of a platform for nonenzymatic glucose sensing employing a novel 3D printed three‐electrode mask‐embedded design. A reservoir‐on‐mask has been fabricated for smart sample insertion to avoid spillage. Working and counter silver electrodes are modified with three different material combinations such as graphene oxide (GO), poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), and GO + PEDOT:PSS, and their performance comparison is demonstrated. It is observed that the GO + PEDOT:PSS modification shows 94.57 and 71.01% higher sensitivity than GO and PEDOT:PSS, respectively, including a higher linearity compared to its counterparts. Glucose concentrations ranging from 50 to 300 mg dL−1 are detected by employing cyclic voltammetry and electrical impedance spectroscopic technique. Herein, a significantly high sensitivity of 18.8 μAmM−1 cm−2 and low limit of detection ≈ 0.4 mM has been achieved for the proposed sensor. The 3D printed mask structure provides 75% higher sample retention ability, greater reliability in terms of sample placement in the sensor and improved test performances. The proposed sensor can provide a stable and large‐scale deployable solution to future biosensing platforms. [ABSTRACT FROM AUTHOR]

The impedance, capacitance and conductance of deionized water-glucose polar solution is measured by employing impedance spectroscopy and a quasi-oscillatory nature of variation with glucose content in the solution is observed. Such quasi-oscillatory nature is attributed to the randomly distributed water-water, water-glucose and glucose-glucose dipole interactions at the molecular level in the solution. A relevant analytical model is developed on the basis of such random distribution of the molecular dipoles and the experimental data agree well with those obtained from the theoretical model. The electrical parameters are measured in the frequency range of 100Hz to 4MHz for the volume fractions of glucose with respect to water in the range of 0.1 to 0.5. The impedance, capacitance and conductance are obtained to be in the range of 1.03 kΩ – 112 kΩ, 34.9 pF – 1.66 nF, and 8.95 μS – 52.9 μS respectively for the glucose volume fraction range considered.

The current article demonstrates a novel diagrammatic approach for the detection and quantification of polar and non-polar/ionic adulterants in milk by employing electrical impedance spectroscopy (EIS). For such study, some commonly used milk adulterants including melamine, starch, urea, allantoin, cyanuric acid, benzoic acid, ammonium sulphate and sodium bicarbonate are incorporated in a controlled manner in the pure milk sample. The presence of such adulterants in milk is confirmed by Fourier transform mid-infrared (FT-MIR) spectroscopy prior to impedimetric measurements. A Pt/Teflon/SiO2/Si biosensor device is fabricated for EIS measurement where the combination of SiO2 and Teflon layer thicknesses are optimized to obtain an appropriate hydrophobicity/dielectricity for the liquid milk samples. The EIS study shows an opposite trend in the variation of electrical impedance, capacitance and conductance for the polar samples in comparison to non-polar/ionic adulterants, upon their controlled addition from 0.5 to 9 (mg/g). Such results are utilized for detection and quantification of the milk-adulterants by developing a diagrammatic approach based on impedimetric phase angle-modulus mapping. Such diagrammatic impedance spectroscopy provides a generic scheme for a rapid, cost-effective and point-of-care detection and quantification of adulterants in milk which can be further extended to other bio-consumables. • EIS detection scheme to identify polar and non-polar/ionic adulterants in milk. • Pt/teflon/SiO2/Si biosensor device fabricated for EIS measurement of liquid sample. • The device can detect milk adulterant concentration ranging from 0.05 to 0.9% (w/w). • Impedimetric phase angle-modulus diagram can map various adulterants in milk. [ABSTRACT FROM AUTHOR]

Dielectric properties of a living biological membrane play crucial role indicating the status of the cell in pathogenic or healthy condition. A distinct variation in membrane capacitance and impedance was observed for peripheral blood mononuclear cell (PBMC) suspensions for diabetic and diabetic-dyslipidemic subjects compared to healthy control. Low frequency region were explicitly considered in electrical analysis to address complex membrane dielectric factors that alter the system capacitance of a PBMC suspension. Such variation was marked in size, morphology and membrane function of PBMCs for control and diseased cases. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies reveal significant alteration in surface morphology of PBMCs in diseased condition. Side scatter of flow cytometry reveals complexity of PBMCs in diseased condition. Changes in size between groups were not found by SEM and forward scatter. Functional alteration in PBMCs was manifested by significant changes in cell membrane properties like Na + , K + ATPase and Ca 2+ , Mg 2+ ATPase activity, reduced plasma membrane fluidity and changes in intracellular Ca 2+ content, which bear significant correlation in diabetic and diabetic dyslipidemic subjects. Therefore, dielectric parameters of PBMCs in diabetic-dyslipidemic challenges may led to interesting correlation opening the possibility of identifying crucial signature biomarkers. [ABSTRACT FROM AUTHOR]