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  • Author: Jakub Szałatkiewicz x
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Open access

Marcin Słoma, Małgorzata Jakubowska and Jakub Szałatkiewicz

Abstract

Superior electrical properties of carbon nanotubes were utilized by the authors in the fabrication of printed resistors. In common applications such as electrodes or sensors, only basic electrical and mechanical properties are investigated, leaving aside other key parameters related to the stability and reliability of particular elements. In this paper we present experimental results on the properties of printed resistive layers. One of the most important issues is their stability under high currents creating excessive thermal stresses. In order to investigate such behavior, a high direct current stress test was performed along with the observation of temperature distribution that allowed us to gain a fundamental insight into the electrical behavior at such operating conditions. These experiments allowed us to observe parametric failure or catastrophic damage that occurred under excessive supply parameters. Electrical parameters of all investigated samples remained stable after applying currents inducing an increase in temperature up to 130 °C and 200 °C. For selected samples, catastrophic failure was observed at the current values inducing temperature above 220 °C and 300 °C but in all cases the failure was related to the damage of PET or alumina substrate. Additional experiments were carried out with short high voltage pulse stresses. Printed resistors filled with nanomaterials sustained similar voltage levels (up to 750 V) without changing their parameters, while commonly used graphite filled polymer resistors changed their resistance value.

Open access

Jakub Szałatkiewicz, Roman Szewczyk, Mateusz Kalinowski, Juhani Kataja, Peter Råback, Juha Ruokolainen and Maciej Kachniarz

Abstract

Microwave devices are widely used in the industry and in the specialized laboratory analyses. Development of such devices requires the possibility of modeling of microwave energy distribution in the specific resonant chambers. Until now, such modeling was possible only with the use of commercial software or was limited to specific cases. The paper presents an open-source module for ELMER software for solving timeharmonic Maxwell’s equations, allowing modeling of microwave waveguide lines. Three test cases of different resonant chambers are investigated at 2.45 GHz frequency. Modeling results obtained from the open-source ELMER Vectorial Helmholtz module show that the application of this software can be effective in R&D works, enabling high-tech small and medium enterprises involvement in advanced microwave technology.