Electrical impedance measurement system to assess in-situ experiments on epithelia under ELF magnetic fields exposure

Purpose: The development of an electric impedance meter based on the impedance spectroscopy technique, for in vitro and in situ experimentation, with cellular epithelia submitted to extremely low frequency magnetic fields in a controlled environment. Unlike other reported systems, a strength of the one presented here is that it avoids the influence of external factors on the experiment. Materials and methods: The designed system employs the electrical impedance values obtained by the impedance spectroscopy technique to determine the parameters of the simple equivalent electrical model of a cellular monolayer. The Madin-Darby Canine Kidney (MDCK) cell cultures were used as subjects of study in the experimental protocol. Results: The validation was carried out by comparing the transepithelial electrical impedance data of the cell cultures obtained with the developed system and those of the Cellzscope® commercial system used as the standard. Non-significant differences were obtained. Conclusion: It was confirmed that the developed system provides reliable values of transepithelial electrical impedance to experiment with cell cultures and take advantage of the controlled environment to reduce the effects of experimental management.

DC and AC Conductivity, Biosolubility and Thermal Properties of Mg-Doped Na2O–CaO–P2O5 Glasses

Bioactive glasses have recently been extensively used to replace, regenerate, and repair hard tissues in the human body because of their ability to bond with living tissue. In this work, the effects of replacing Na2O with MgO on the electrical, biosolubility, and thermal properties of the target glass 10Na2O–60P2O5–30CaO (in mol%) were investigated. The electrical properties of the glasses were studied with the impedance spectroscopy technique. At 473 K, DC conductivity values decreased from 4.21 × 10−11 to 4.21 × 10−12 S cm−1 after complete substitution of MgO for Na2O. All samples had a similar activation energy of the DC conduction process ~1.27 eV. Conduction mechanisms were found to be due to hop of ions: Na+, Mg2+, and probable H+. FTIR analysis showed that, as the Mg content increased, the Q2 unit (PO2−) shifted towards higher wavenumbers. The proportion of Q3 unit (P2O5) decreased in the glass structure. This confirmed that the replacement of Na+ by Mg2+ was accompanied by concurrent polymerization of the calcium–phosphate glass network. The biosolubility test in the phosphate-buffered saline solution showed that the magnesium addition enhanced the biosolubility properties of Na2O–CaO–P2O5 glasses by increasing their dissolution rate and supporting forming CaP-rich layers on the surface. The glass transition temperature increased, and thermal stability decreased substantially upon substitution of Na2O by MgO.

Crystal structure and electrical properties of Ag6PS5I single crystal

The single crystals of quaternary halogen Ag6PS5I were grown from the solution–melt by means of a vertical zone crystallization method. The crystal structure has been ascertained using the Rietveld method. Investigation of electrical conductivity was carried out using the impedance spectroscopy technique within the frequency range 1·101 – 3·105 Hz and temperature interval 293–383 K on gold contacts applied by chemical deposition from solution. Ionic (1.79·10-3 S/cm) and electronic (1.64·10-6 S/cm) components of electrical conductivity have been determined using the Nyquist plots. The mechanism of ionic conductivity for Ag6PS5I single crystal has been proposed which can be considered as ion diffusion through “channels” Ag2–Ag2.

WEARABLE SWEAT SENSING DEVICE FOR DETECTION OF IBD BIOMARKERS

Introduction Inflammatory Bowel Disease affects 1.2 million in the United States. Flare-up of the disease occurs in a random way and current testing methods lack ability for real-time prediction of a flare up. The levels of cytokines elevate during a flareup. Therefore, we hypothesize that real-time monitoring of cytokine biomarkers can be useful for early detection of flare-ups and provide better patient management. In this context, sweat-based diagnostics can be promising for real-time tracking of IBD biomarkers. Materials and Methods A wearable SWEATSENSER was developed by functionalization of specific affinity capture probes (IL-1β, CRP antibodies) on metal/semiconducting interface deposited on a porous patch substrate. Electrochemical impedance spectroscopy technique was used to detect the interaction between the specific antibody and target analyte. The developed SWEATSENSER was tested on 20 healthy human subjects in compliance with an approved IRB at UT Dallas. Continuous on-body measurements were recorded to report IL-1β, CRP levels in sweat in real-time. Results In this work, a wearable multiplexed sweat sensor for detection of IL-1β, CRP in sweat has been demonstrated. The sensor demonstrates a limit of detection of 1 pg/mL with a dynamic range from 1 pg/mL- 512 pg/mL for both the biomarkers in sweat. The sweat sensor demonstrated excellent correlation with reference ELISA method (Pearson’s r ≥0.95). On-body monitoring using sweat sensor from passively perspired human sweat demonstrated a mean concentration of 28 pg/mL for IL-1β in healthy cohort. Conclusion A wearable sweat sensor was developed to monitor potential IBD markers in sweat. The developed device can be useful in better management of IBD patients.

Functional Energy Accumulation, Photo- and Magnetosensitive Hybridity in the GaSe-Based Hierarchical Structures

We report on the complex GaSe-based hierarchical structures GaSe(CS(NH2)2), GaSe(SmCl3) and GaSe(CS(NH2)2(SmCl3)) synthesized by an intercalation method. The conductive properties of synthesized clathrates and their relation to hierarchical structural complexity were explored by an impedance spectroscopy technique. The impedance response, thermostimulated discharge spectra, and photo- and magnetoresistive effects are reported. Based on the obtained results, the impurity energy spectra were calculated. A strong low-frequency inductive response, observable in the GaSe(SmCl3) clathrate, makes this material promising for the development of gyrator-free nanodelay lines potentially applicable in nanoelectronics. Hierarchical GaSe(CS(NH2)2(SmCl3)) clathrate, on the other hand, reveals hysteresis of the current–voltage characteristics, apparently confirming an accumulation of electric energy at interphase boundaries. A relevant spin battery effect, observable experimentally in stationary magnetic fields, demonstrates a principal possibility of the electric energy accumulation at a quantum level.

Structural, Microstructural and Electrochemical Studies of Co/Mn Derived Oxides as Protective Layers for Intermediate Temperature SOFCs

Designing highly protective and superior electrically conductive coatings from Cobalt-manganese doped/un-doped oxide materials (CMOs) is the main target of this study. The as-prepared nanopowders were synthesized via glycine nitrate process (GNP) at moderate annealing temperature afterword characterized using several techniques including X-rays diffraction (XRD), Field emission scanning electron microscopy (FE-SEM) and electrochemical impedance measurements at room temperature. The XRD results revealed a pure phase of spinel structure with particle size range 75-81 nm for the doped CMO samples. SEM micrographs exhibited morphology with fine aggregate of particles. The incorporation of different ions of Cu, Ni, Fe and Na into the CMOs structure showed a significant increase in the diffusivity of ions and remarkable improvement in the crystallinity. AC electrical conductivity was also measured for the compacted pellets after sintering at 850°C using the electrochemical impedance spectroscopy technique at room temperature. From the obtained results it could be concluded that the polarization resistance of pure and modified CMOs samples show similar behavior ranged from 5 to 6 k Ω.

Electrical Behavior of Liquid Crystal Devices with Dielectric Nanoparticles

Nowadays, the development of new devices based on liquid crystal (LC) materials requires improved tuning characteristics according to the application. One approach for this improvement is the use of nanomaterials with the capability of modifying the effective properties of the doped LC mixture. In this work, we analyze the electrical behavior of a titanium dioxide (TiO2) nanoparticle-doped liquid crystal cell using an equivalent circuit. The circuit parameters have been obtained using the impedance spectroscopy technique and time response measurements. The particularity of the samples designed is that the nanoparticles are not dispersed in the LC. Instead of that, nanoparticles are randomly deposited on one of the electrodes. Measurements show that the presence of the nanoparticles increases the temperature sensitivity of the equivalent cell capacitance and the capacitance difference between switched and nonswitched states. These results could be quite useful in the design of novel liquid crystal electronic devices and sensors.