3D-printing technology is opening up new possibilities for the co-printing of sensory elements. While quasi-static research has shown promise, the dynamic performance has yet to be researched. This study researched smart 3D structures with embedded and printed sensory elements. The embedded strain sensor was based on the conductive PLA (Polylactic Acid) material. The research was focused on dynamic measurements of the strain and considered the theoretical background of the piezoresistivity of conductive PLA materials, the temperature effects, the nonlinearities, the dynamic range, the electromagnetic sensitivity and the frequency range. A quasi-static calibration used in the dynamic measurements was proposed. It was shown that the temperature effects were negligible, the sensory element was linear as long as the structure had a linear response, the dynamic range started at ∼ 30 μ ϵ and broadband performance was in the range of few kHz (depending on the size of the printed sensor). The promising results support future applications of smart 3D-printed systems with embedded sensory elements being used for dynamic measurements in areas where currently piezo-crystal-based sensors are used.
Synthesis of ionic liquid 1-heptyl-2,3-dimethylimidazolium bromide was accomplished with the assistance of ultrasound, microwave irradiation, and a continuously operated microreactor and was compared with a conventional laboratory scale process applying magnetic stirring and water-bath heating. Results were compared with respect to process productivity, energy consumption, and product colourisation as an indicator of its purity. By using nonconventional technologies, volumetric productivity was 10- to 30-fold superior, while energy consumption was reduced by 45%–65%. Among the alternatives tested, ultrasound-assisted synthesis was shown as the most efficient one in terms of volumetric productivity (4.40 mol l-1 h-1) and specific power consumption (909.1 W h mol-1), while microwave-assisted process was the least favourable. However, only a microreactor system enabled the synthesis of a noncoloured product resulting from very efficient mixing and temperature control. Due to significant process intensification along with high product quality and superior industrial perspectives, a continuous quaternisation within microchannels could be selected as the most promising green approach among the alternatives tested in this study. Integration of ultrasound and microreactor technology including miniaturised heat exchanger is foreseen for process intensification.
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