Investigation of Magneto-Mechanical Behaviours of Magnetic-Elastomeric Membranes Using Fibre-Optic Interferometry

Soft ME (magnetic-elastomeric) composites are a class of smart materials formed by embedding magnetic particles into non-magnetic elastomer matrix host and curing into various shapes. When exposed to the external magnetic field, the cured ME material can be accordingly magnetized and remotely activated to rotate or translate under the magnetic torque or gradient force, or even deform due to the magnetic dipole-dipole interactions. Using a host of fabrication techniques, ME composites can be created as surface coatings or free-standing films with tailorable size and high flexibility and integrated with sophisticated devices of various geometries according to different application scenarios, such as physiological sensing in wearable electronics, wireless actuation in soft robotic, and microfluidic devices. Their superior mechanical stability, high fabrication flexibility and untethered magnetic actuation make it an ideal candidate for smart device development.<br/> <br/>Nevertheless, how to optimize the magnetic responsiveness of ME coatings for more efficient actuation with less power remains challenging, as there is a lack of fundamental knowledge about the magneto-mechanical behaviours of the ME materials under different magnetic field conditions. Performance evaluation techniques with high enough resolution are in high demand.<br/> <br/>This work aims at investigating the magneto-mechanical responses of the ME materials using a newly-established fibre-optic interferometric sensing system which is capable of detecting small mechanical changes (deformation or deflection) in nanometre scale. This highly sensitive technique allows closer look of the magneto-mechanical behaviours of the ME materials and enables differentiation of two entangled effects: magneto-striction induced deformation and magnetic gradient force induced deflection. More studies on optimization of magnetic actuating performance by tuning particle concentration and coating thickness will be further conducted. Therefore, by clarifying the basic issues of magnetic actuation of the ME material, it is promising to witness great development of biomedical devices in near future.