Anisotropic composite polymer for high magnetic force in microfluidic systems
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Anisotropic carbonyl iron–polydimethylsiloxane (PDMS) composites were developed and implemented in microfluidic devices to serve as magnetic flux concentrators. These original materials provide technological solutions for heterogeneous integration with PDMS. Besides microfabrication advantages, they offer interesting modular magnetic properties. Applying an external magnetic field during the PDMS reticulation leads to the formation of 1D agglomerates of magnetic particles, organized in the non-magnetic polymer matrix. This induces an increase in susceptibility as compared to composites with randomly dispersed particles. In this report, we explored the gain in reachable magnetophoretic forces in operating microfluidic devices, from the study of magnetic microbeads motion injected in the microchannel. We show that even at relatively large distances from the magnetically functionalized channel wall, the anisotropic composite leads to a factor two increase in the magnetophoretic force. Finally, further investigations based on finite element description suggest that the measured benefit of anisotropic composite polymers does not only rely on the global susceptibility increase but also on the local magnetic field gradients originating from the microstructure.
KeywordsMagnetophoretic force Magnetic anisotropy Composite polymer Microstructuration/local magnetic gradients
The authors are indebted to the EEA doctoral school and the institute Carnot Ingénierie@Lyon and for their support and funding. This work was also supported by the University of Lyon 1, through its program “BQR Accueil EC 2015”. The authors are grateful to R. Checa for technical assistance at the “Centre de Magnétométrie de Lyon” and to N. Terrier for his technical support at the NanoLyon cleanroom facility.
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