A magnetic nano-composite soft polymeric membrane

Abstract

There is an increased need for low cost actuation technologies at the micro and nanoscale. Magnetically responsive polymer-based materials are good candidates for numerous applications in microsystems for actuation and sensing purposes. In this work, we report on nano-polymer composite magnetic silicone-based membranes, which provide the low elastic modulus needed for magnetic actuation to be effective at small scales. Passivated crystalline cobalt (~37 nm) and water based iron/cobalt (~100 nm) nanoparticles (NPs) have been synthesized using a chemical route at 50 °C and at room temperature, respectively. The NPs were characterized by Fourier Transform Infrared Spectroscopy, X-Ray Diffraction, Atomic Force Microscopy and Vibrating Sample Magnetometry (VSM). The NPs are then uniformly dispersed in a polydimethyl siloxane (PDMS) polymer matrix in order to fabricate smooth and flexible magnetic composite membranes. The magnetic properties of the membranes for different amounts of cobalt and iron NPs (16 and 25 wt%) were characterized by VSM and deflection measurements. Co/Fe PDMS composite membranes of about 50 mm diameter and ~250 μm thickness were used under the application of ~400 Oe magnetic fields. The cobalt-PDMS membrane shows the largest deflection (~900 vs. ~80 μm for an iron-PDMS membrane). The deflections observed on these membranes are found to have a linear dependence on the applied magnetic field.