  Cloaking effects have now been identified in almost every field of physics.
In all cases, substrate-carved metamaterials make the reshaping of the
concealed volume impossible. In fluids, recognizing that d'Alembert's paradox
describes in itself a hydrodynamic cloaking mechanism, we propose and
characterize experimentally a framework to cloak both flow and transport
simultaneously within a reshapable fluid volume. The properties of microfluidic
cloaks as open-space diffusion filters (O-Filters) are further investigated.
They reveal a strong topological analogy with classical H-Filters in
microfluidics.
