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Measurement Method for Aesthetic Medicine
Published in P. Arpaia, U. Cesaro, N. Moccaldi, I. Sannino, Non-Invasive Monitoring of Transdermal Drug Delivery, 2022
P. Arpaia, U. Cesaro, N. Moccaldi, I. Sannino
Strictly speaking, a tissue is a collection of similar cells specialised to fulfil a specific function. The cells lie in a supporting framework, called matrix, made of materials produced also by surrounding cells. The physiological behaviour of a cell is defined both by internal elements and parameters, as well as by external factors, namely the extracellular fluid. The fluid is often secreted by cells to provide a constant environment for cellular operations; thus, it has the same composition of intracellular fluid, but with a different concentration. This fluid is circulated throughout the body along with the blood, in the spaces between blood vessel and tissues, where material exchange occurs by diffusion. The body fluid is mainly a water solution with ions and other substances [144]. Therefore, a human tissue can be approximated to an electrolyte solution containing a large amount of cells. In conductometry, the quantity of a conductive substance (solute) dissolved in a solution can be estimated from the variation of solution resistance. In fact, the equivalent conductance of the solution also depends on how much solute is actually present.
Nanobiosensors
Published in Vinod Kumar Khanna, Nanosensors, 2021
What electrochemical techniques have been used for biomolecule sensing? Various electrochemical techniques have been used for sensing of biomolecules. Some common techniques are voltammetry (an analytical technique for the detection of minute quantities of substances by measuring the currents generated or the substances deposited on electrodes placed in electrolytic solutions, when known voltages are applied), amperometry (the measurement of current at a single applied potential), potentiometry (measurement of potential under the conditions of zero current flow), impedometry (analysis of a sample by impedance measurements), and conductometry (determination of the quantity of a material present in a mixture by measurement of its effect on the electrical conductivity of the mixture).
Electrochemical Composition Measurement
Published in John G. Webster, Halit Eren, Measurement, Instrumentation, and Sensors Handbook, 2017
Michael J. Schöning, Arshak Poghossian, Olaf Glück, Marion Thust
In addition to potentiometry, conductometric analysis represents the most important nonfaradaic method. Conductometry is based on the measurement of the electrical conductance of an electrolyte solution, which directly depends on the number of positively and negatively charged species in the solution. This analysis method is limited due to its nonselective nature, because all ions in the solution will contribute to the total conductance. Nevertheless, direct conductance measurements play an important role in the analysis of binary water/electrolyte mixtures, for example, in chemical water monitoring. The technique can also be applied to ascertain the endpoint detection in conductometric titrations for the determination of numerous substances.
Progress on electrochemical sensors for the determination of heavy metal ions from contaminated water
Published in Journal of the Chinese Advanced Materials Society, 2018
Xiangzi Dai, Shuping Wu, Songjun Li
At present, electrochemical methods of heavy metal detection mainly include voltammetry,[21–24] potentiometry [25–27] and conductometry.[28,29] Voltammetry is actualized through analyzing the current-potential or potential-time curve. The principle of stripping voltammetry for detecting heavy metals is that the heavy metals are concentrated at the negative electrode under negative voltage, and then the reverse electrode potential is used to extract the heavy metal ions. The heavy metal is quantitative misanalysed based on voltammetric curves obtained during dissolution. Due to its wide application range and high sensitivity for the determination of heavy metal ions in solution, the anodic stripping voltammetry has become the most mature and most commonly used electrochemical detection method and could be used for almost all of the common heavy metal detections. Recently, antimony film electrodes have been developed for anodic stripping voltammetry of heavy metal ions in environmental and biological samples.[30] Tesarova et al. have prepared an antimony film carbon paste electrode (SbF-CPE) based on the carbon paste substrate electrode as a ‘mercury-free’ electrochemical sensor for measuring some selected trace heavy metals with square-wave anodic stripping voltammetry.[31] The newly developed sensor revealed highly linear behavior in the examined concentration range from 5 to 50 mu g/L, with limits of detection (LOD) of 0.8 mu g/L for Cd(II), and 0.2 mu g/L for Pb(II). Potentiometry is the determination of electromotive force or electrode potential under the condition that the battery current is zero, so that the concentration of the determined is measured by the nexus between the electrode potential and the concentration. Compared with the voltammetry, it is an attractive feature of potentiometry that the equipment is rather inexpensive and simple. A new sulfur-containing macrocyclic diamide was synthesized by Shamsipur et al. with an active component for fabrication of PVC-based polymeric membrane (PME), coating graphite (CGE) and silver wire electrodes (CWE) for sensing Cd(II) ion.[32] The CGE was used as a proper detection system in flow-injection potentiometry with a linear Nernstian range of 32 nM to 0.14 M (LOD = 13 nM). Furthermore, conductometry is another method of measuring the ionic concentration in a solution by gauging electrolytic conductivity of the solution. Conductometry has important applications in analytical chemistry, and is often applied to determine the total conductance of the sample or to analyze the end point of titrations that include ions.[33,34]