Fabrication and Testing of Asymmetric Magnetic-Polymer Flexible Sheets for Biomedical Actuated Devices

Abstract Flexible actuated sheets are currently being used in different devices in the biomedical field for a variety of different applications. Examples of biomedical devices that use flexible actuated sheets are neural probes, microneedles, micropumps for insulin, intraocular and inner ear drug delivery systems. Among them, micropumps are one of the most flexible and popular devices. In fact, micropumps are being extensively studied for multiple biomedical applications — controlled drug delivery systems, artificial sphincter prosthesis, cell culturing, micro-fluidic analyses. One of the most important applications for actuated membranes is in drug delivery systems, but there are multiple challenges that exist including maintaining controlled flow rate, reaching delicate tissues, and preventing complex side effects. In this paper, the effect of an inhomogeneous distribution of magnetic particles in the membrane used for actuation is studied for the first time. The fabrication and testing of asymmetric thin flexible sheets magnetic actuators are presented. Focus of this research is to fabricate thin polymeric sheets with thickness range of 120–125μm, with asymmetric distribution of magnetic nano/micro particles. Iron oxide (Fe3O4) particles are embedded into polymeric membranes made of Polydimethylsiloxane (PDMS). From the perspective of biomedical application, PDMS is chosen for its excellent biocompatibility and Fe3O4 for its non-toxic nature. The particles are mixed with the PDMS polymeric solution and micromagnets are used to localize the magnetic particles during the curing process at selected locations to create asymmetry into the particles’ distribution. Fe3O4 – PDMS membranes are fabricated and mounted to a fixture to observe deflection by using a camera. An external magnetic field is applied for the actuation of the membrane and two measurement types are made: static and dynamic. A permanent magnet is used for generating the external magnetic field, which is attached to a piezoelectric actuator. The effect of the distribution of magnetic particles are investigated in terms of the deflection of membranes for both static and dynamic behavior. A comparative study of membranes with inhomogeneous and randomly distributed particles is carried out. This work shows that the inhomogeneous distribution of particles has a positive effect on the deflection of the membranes, making them favorable for a wide range of applications involving localized and targeted treatments and precision medicine. Since magnetic actuation does not require onboard batteries or other power systems, it is very convenient to use. Magnetically actuated sheets can be used in Hyperthermia to have enhanced results due to asymmetric distribution of magnetic particles.