The invention concerns a method for making a suspended microstructure comprising the following steps: forming a masking layer on a substrate top surface; structuring the masking layer to form at least an opening substantially defining the surface of said microstructure and for exposing part of the substrate corresponding to said surface; causing by electrochemical process said exposed semiconductor material to become porous over a predetermined thickness; electropolishing the semiconductor material underlying said microstructure made porous to form a cavity enclosing at least partially said microstructure beneath the masking layer level; and releasing said microstructure made porous to form a microstructure suspended to said substrate by at least a connection portion of its perimeter to provide said microstructure with mobility outside the substrate plane.