Design and Fabrication of a Conductometry System for Fast Detection of Pathogenic Bacteria in Human Urine

Background: Common methods for identifying the infectious bacteria in human urine are mainly time-consuming and costly. Therefore, the most reliable method for detecting the urinary tract infections is the urine culture, which requires at least 48 hours to identify infectious factors. Objectives: It is important to detect the bacteria in urine rapidly, simply, and accurately. Materials and Methods: In this work, the variations in the electrical conductivity and dielectric coefficient of the urine sample due to changes in the concentration of infectious bacteria have been studied. Furthermore, an appropriate measurement system was prepared for impedancemetry and conductometry. Results: We showed that the detection time was reduced to about an hour. Finally, the accuracy of the device for diagnosis and precision of measurement were evaluated and compared by the detection method for bacterial culture. Conclusion: In this work, the detection time was reduced to about 1 hour.

Effect of Metallization on the Electromechanical Properties of Microfluidically Synthesized Hydrogel Beads

This investigation demonstrates that metallization can be used to tailor the electromechanical properties of polymer beads. Rigid ion exchange resin beads and softer microfluidically synthesized polyionic liquid hydrogel beads were metallized using an ion exchange process. Metallization increased bead stiffness and dielectric coefficient while reducing resistivity in all beads examined here. Gold-filled beads were preferable over platinum-filled beads as they generated greater changes in electrical properties with smaller increased stiffness. These properties could be further altered by performing multiple metallization steps, but diminishing returns were observed with each step. Ion exchange resin beads were always stable after multiple metallization steps, but polyionic beads would often rupture when repeatedly compressed. Polyionic beads with higher ionic liquid (IL) content were more fragile, and beads synthesized from monomer solutions containing 1% IL were mechanically robust after three metallization steps. These 1% IL beads delivered similar electrical properties as the IONAC beads that also underwent three metallization steps at a significantly reduced stiffness.

Relative dielectric constants and selectivity ratios in open ionic channels

We investigate the effects of the relative dielectric coefficient on ionic flows in open ion channels, using mathematical analysis of reasonably general Poisson-Nernst-Planck type models that can include the finite sizes of ions. The value of the relative dielectric coefficient is of course a crucial parameter for ionic behavior in general. Using the powerful theory of singularly perturbed problems in applied mathematics, we show that some properties of open channels are quite insensitive to variation in the relative dielectric coefficient, thereby explaining such effects seen unexpectedly in simulations. The ratio between the total number of one ion species and that of another ion species, and the ratio between the flux of one ion species and that of another ion species do not depend significantly on the relative dielectric coefficient.

Inverse Analysis for Inhomogeneous Dielectric Coefficient of Pavement Material Based on Genetic Algorithm

The key of ground penetrating radars application lies in the calculation of dielectric coefficient. The pavement materials are inhomogeneous medium in fact, the particle surface can induce the scatter and diffraction of electromagnetic wave. The inhomogeneous dielectricity can change the characteristics of reflected wave. It may even cause background noise of reflected signal, which will lead to mistakes in signal interpretation. Therefore it is necessary to analyze the inhomogeneous dielectric coefficients by GPR. This paper proposes the solutions of inverse analysis for inhomogeneous dielectric coefficients of pavement materials used GPR data. Two examples are given to assess the validity of genetic algorithms in inversion of pavement materials inhomogeneous dielectricity. The results show that genetic algorithm can converge into true solutions well. The backcalculated inhomogeneous dielectric coefficients can help to evaluate pavement properties further.