Inkjet Printing of High Aspect Ratio Superparamagnetic SU-8 Microstructures with Preferential Magnetic Directions

Micromachines

Lo໼ Jacot-Descombes¹  Maurizio R. Gullo¹  Victor J. Cadarso¹  Massimo Mastrangeli¹  Olgaç Ergeneman²  Christian Peters³  Philipe Fatio²  Mouhamad A. Freidy¹  Christofer Hierold³  Bradley J. Nelson² 

[1] Microsystems Laboratory, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland; E-Mails:;Multi-Scale Robotics Lab, Institute of Robotics and Intelligent Systems, ETH Zurich, 8092 Zurich, Switzerland; E-Mails:;Micro and Nanosystems, ETH Zurich, 8092 Zurich, Switzerland; E-Mails:

关键词: inkjet printing;    polymer;    superparamagnetic SU-8;    hemispherical structures;    thermal curing;    low topographical confinement;    magnetic anisotropy;   

DOI  :  10.3390/mi5030583

来源: mdpi

【 摘 要 】

Structuring SU-8 based superparamagnetic polymer composite (SPMPC) containing Fe₃O₄ nanoparticles by photolithography is limited in thickness due to light absorption by the nanoparticles. Hence, obtaining thicker structures requires alternative processing techniques. This paper presents a method based on inkjet printing and thermal curing for the fabrication of much thicker hemispherical microstructures of SPMPC. The microstructures are fabricated by inkjet printing the nanoparticle-doped SU-8 onto flat substrates functionalized to reduce the surface energy and thus the wetting. The thickness and the aspect ratio of the printed structures are further increased by printing the composite onto substrates with confinement pedestals. Fully crosslinked microstructures with a thickness up to 88.8 μm and edge angle of 112° ± 4° are obtained. Manipulation of the microstructures by an external field is enabled by creating lines of densely aggregated nanoparticles inside the composite. To this end, the printed microstructures are placed within an external magnetic field directly before crosslinking inducing the aggregation of dense Fe₃O₄ nanoparticle lines with in-plane and out-of-plane directions.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland.