The purpose of this study was to develop a new apparatus for in vitro studies applying low frequency electrical fields to cells without interfering side effects like biochemical reactions or magnetic fields which occur in currently available systems. We developed a non-invasive method by means of the principle of transformer-like coupling where the magnetic field is concentrated in a toroid and, therefore, does not affect the cell culture. Next to an extensive characterization of the electrical field parameters, initial cell culture studies have focused on examining the response of bone marrow-derived human mesenchymal stem cells (MSCs) to pulsed electrical fields. While no significant differences in the proliferation of human MSCs could be detected, significant increases in ALP activity as well as in gene expression of other osteogenic markers were observed. The results indicate that transformer-like coupled electrical fields can be used to influence osteogenic differentiation of human MSCs in vitro and can pose a useful tool in understanding the influence of electrical fields on the cellular and molecular level.
The electrocaloric effect of 0.92 Pb(Mg1/3Nb2/3)O3‐0.08 PbTiO3 (PMN‐8 PT) bulk ceramics and multilayer ceramic (MLC) structures is reported. The results are compared to lead‐free, barium‐titanate‐based materials. Phase transition temperature and electrocaloric temperature change could be altered by targeted doping and this is discussed with the help of dielectric and electrocaloric measurements. By reduction of single layer thickness in MLCs, electrical loads and thus electrocaloric temperature changes of PMN‐8 PT based multilayers could be increased. Simulations that outline the intrinsic cooling performance of electrocaloric MLC components in dependence of the multilayer design and operation frequency for two different modes of heat transfer are presented. The performance of the fabricated MLC layout for a driving frequency of 1 Hz is discussed in detail and an optimum layout by varying of design parameters derived. Additionally, the effect of driving frequency on the electrocaloric cooling power is investigated.
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