  Current optical manipulation techniques rely on carefully engineered setups
and samples. Although similar conditions are routinely met in research
laboratories, it is still a challenge to manipulate microparticles when the
environment is not well controlled and known a priori, since optical
imperfections and scattering limit the applicability of this technique to
real-life situations, such as in biomedical or microfluidic applications.
Nonetheless, scattering of coherent light by disordered structures gives rise
to speckles, random diffraction patterns with well-defined statistical
properties. Here, we experimentally demonstrate how speckle fields can become a
versatile tool to efficiently perform fundamental optical manipulation tasks
such as trapping, guiding and sorting. We anticipate that the simplicity of
these "speckle optical tweezers" will greatly broaden the perspectives of
optical manipulation for real-life applications.
