Esteves David Seixas, Melo Amanda, Alves Sónia, Durães Nelson, Paiva Maria C, Sequeiros Elsa W
Department of Mechanical Engineering, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal.
CeNTI, Centre for Nanotechnology and Advanced Materials, 4760-034 Vila Nova de Famalicão, Portugal.
Micromachines (Basel). 2025 Jan 8;16(1):68. doi: 10.3390/mi16010068.
Magnetic field-assisted control of magnetite location is a promising strategy for developing flexible, electrically conductive sensors with enhanced performance and adjustable properties. This study investigates the effect of static magnetic fields applied on thermoplastic elastomer (TPE) composites with magnetite and multi-walled carbon nanotubes (MWCNT). The composites were prepared by compression moulding and the magnetic field was applied on the mould cavity during processing. Composites were prepared with a range of concentrations of magnetite (1, 3, and 6 wt.%) and MWCNT (1 and 3 wt.%). The effect of particle concentration on composite viscosity was investigated. Rheological analysis showed that MWCNTs significantly increased the composite viscosity while magnetite had minimal impact, ensuring stable processing and facilitating particle orientation under a static magnetic field. Particle orientation and electrical conductivity were evaluated for the composites prepared with different particle concentrations under different processing temperatures. Magnetic field application at 190 °C enhanced magnetite/MWCNT interactions, substantially reducing electrical resistivity while preserving thermal stability. The composites showed no degradation at 220 °C and above, demonstrating suitability for high-temperature applications requiring thermal resilience. Furthermore, magnetite's magnetic response facilitated precise sensor positioning and strong adhesion to polyimide substrates at 220 °C. These findings demonstrate a scalable and adaptable approach for enhancing sensor performance and positioning, with broad potential in flexible electronics.
磁场辅助控制磁铁矿的位置是开发具有增强性能和可调特性的柔性导电传感器的一种有前途的策略。本研究调查了施加静态磁场对含有磁铁矿和多壁碳纳米管（MWCNT）的热塑性弹性体（TPE）复合材料的影响。复合材料通过压缩模塑制备，并且在加工过程中对模腔施加磁场。制备了一系列不同浓度的磁铁矿（1、3和6 wt.%）和MWCNT（1和3 wt.%）的复合材料。研究了颗粒浓度对复合材料粘度的影响。流变学分析表明，MWCNT显著增加了复合材料的粘度，而磁铁矿的影响最小，确保了稳定的加工过程，并有利于在静态磁场下颗粒的取向。对在不同加工温度下用不同颗粒浓度制备的复合材料的颗粒取向和电导率进行了评估。在190°C施加磁场增强了磁铁矿/MWCNT的相互作用，在保持热稳定性的同时大幅降低了电阻率。复合材料在220°C及以上温度下未出现降解，表明适用于需要热弹性的高温应用。此外，磁铁矿的磁响应有助于在220°C下精确地定位传感器并使其牢固地粘附在聚酰亚胺基板上。这些发现证明了一种可扩展且适应性强的方法来提高传感器性能和定位，在柔性电子领域具有广泛的潜力。
