Artificial membranes are increasingly being studied, particularly in biology and health, to understand life and for therapeutic purposes, or in fields related to optics to be used as flexible photonic devices. These membranes are often made of polydimethylsiloxane (PDMS) films, a polymer used for decades for its tunable elastic modulus, biocompatibility and transparency.

Researchers at IRIG have developed a new type of membrane partly derived from studies on magnetic particles for biology (such as those used for the destruction of cancer cells induced by magnetomechanical vibrations). These innovative membranes, which incorporate periodic 2D networks of magnetic particles (Figure), are biocompatible and magnetically actuated. Their great potential lies in their ability to be remotely activated by an external magnetic field; from a planar state in a null field, they become concave under the action of an applied magnetic field, and thus constitute diffraction gratings for the visible, whose deformations are finely regulated magnetically. Experimental optical responses controlled magnetically show interference spots (Figure) that gradually stretch into a series of fringes when the magnetic field is applied. These diffraction patterns are in excellent agreement with the magnetomechanical and optical analytical models that are developed at IRIG. Deformations of a few microns can be controlled on membranes of centimetric diameters.
More generally, these results suggest that this type of biocompatible and operable magneto-elastic membranes has potential applications in adaptive optics, photonic devices, but also in biophysics, biology and biomedical fields.



A - Photograph of membranes suspended on the holes engraved on the back of the silicon plate. Zoom: Scanning electron microscope photography of the magnetic lattice (Ni₈₀Fe₂₀) integrated into the membrane, constituting the deformable 2D diffraction lattice.
B - Diagram of the magnetic actuation of a membrane illuminated by a laser beam, initially flat, deformed approaching a magnet.
C - Diffraction pattern strongly impacted by low membrane deflections.