Sciospec - Electrical Impedance. At its best.
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Email: info@sciospec.de
Sciospec Scientific Instruments GmbH
Leipziger Straße 43b, 04828 Bennewitz, Germany
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Measuring the viscosity of very small sample volumes is of high interest in many fields especially in miniaturized and micro-fluidic systems. This application note describes an approach using the change of the impedance spectrum of a Thickness Shear Mode Resonator in combination with a sophisticated fitting algorithm. The simple setup of the measuring system enables easy integration in existing micro-fluidic settings with almost no adaption. As validation of the Sciospec ISX-3 a comparison to theoretical values and to a commercially available vector network analyzer on the same setup is provided.
The measurement of the viscosity is very well known for sample volumes larger than a couple milliliters. The standard viscometers use either rotating parts, a flow through, a capillary system or falling spheres. This application note describes an example of measuring smaller sample volumes with no need for mechanical parts.
Online monitoring of deposition or coating processes is highly relevant in a variety of fields including biocompatible coatings for medical implants. As of now mostly “simple” resonance tracking of quartz crystal microbalances is used for these purposes. The joint research project by AG Mayr, Leibniz Institute of Surface Modification Leipzig1 and Sciospec was aiming for more specific insights into the process itself. Especially nano-structural formation and adhesion parameters are of high interest. This application note describes the first step of data acquisition and parameter estimation.
Deep brain stimulation (DBS) is effective for the treatment of patients with Parkinson’s disease (PD), especially in advanced stages which are refractory to conventional therapy. Despite of the regular use in clinical therapy, rodent models for basic research into DBS are not routinely available. The main reason is the geometry difference from rodents to humans, imposing larger problems in the transfer of the stimulation conditions than from primates to humans. For rodents, the development of miniaturized mobile stimulators and stimulation parameters, as well as improved electrode materials and geometry are desirable. The impedance of custom made, cylindrical (contact diameter 200 µm, length 100 µm), platinum/iridium electrodes has been measured in vivo for two weeks to characterize the influence of electrochemical processes and of the adherent cell growth at the electrode surface. During the encapsulation process, the real
part of the electrode impedance at 10 kHz doubled with respect to its initial value after a characteristic decrease by approximately one third at the second day. An outlook is given on further investigations with different electrode designs for long-term DBS.
Deep brain stimulation (DBS) is an invasive therapeutic option for patients with Parkinson’s disease (PD) but the mechanisms behind it are not yet fully understood. Animal models are essential for basic DBS research, because cell based in-vitro techniques are not complex enough. However, the geometry difference between rodents and humans implicates transfer problems of the stimulation conditions. For rodents, the development of miniaturized mobile stimulators and adapted electrodes are desirable. We implanted uni- and bipolar platinum/iridium electrodes in rats and were able to establish chronical instrumentation of freely moving rats (3 weeks). We measured the impedance of unipolar electrodes in-vivo to characterize the influence of electrochemical processes at the electrode-tissue interface. During the encapsulation process, the real part of the electrode impedance at 10 kHz doubled after 12 days and increased almost 10 times after 22 days. An outlook is given on the quantification of the DBS effect by sensorimotor behavioral tests
Unexpected adverse effects on the cardiovascular system remain a major challenge in the development of novel active pharmaceutical ingredients (API). To overcome the current limitations of animal-based in vitro and in vivo test systems, stem cell derived human cardiomyocyte clusters (hCMC) offer the opportunity for highly predictable pre-clinical testing. The three-dimensional structure of hCMC appears more representative of tissue milieu than traditional monolayer cell culture. However, there is a lack of long-term, real time monitoring systems for tissue-like cardiac material. To address this issue, we have developed a microcavity array (MCA)-based label-free monitoring system that eliminates the need for critical hCMC adhesion and outgrowth steps. In contrast, feasible field potential derived action potential recording is possible immediately after positioning within the microcavity. Moreover, this approach allows extended observation of adverse effects on hCMC. For the first time, we describe herein the monitoring of hCMC over 35 days while preserving the hCMC structure and electrophysiological characteristics. Furthermore, we demonstrated the sensitive detection and quantification of adverse API effects using E4031, doxorubicin, and noradrenaline directly on unaltered 3D cultures. The MCA system provides multi-parameter analysis capabilities incorporating field potential recording, impedance spectroscopy, and optical read-outs on individual clusters giving a comprehensive insight into induced cellular alterations within a complex cardiac culture over days or even weeks.
Wound infection status is a relevant diagnostic parameter to enhance wound treatment towards better healing rate. Impedance evaluation is a powerful tool to measure the inflammatory response like the released DNA of neutrophils. In our research we investigated the dielectric behaviour of neutrophils settled on electrodes in vitro. The cells have been stimulated to react in the same way as in a wound infection. The result is a significant impedance deviation of about 50 % with comparable amount of cells like in an infected wound. Microscopic fluorescence verifications acknowledge these findings.