  Optical tweezers employing forces produced by light underpin important
manipulation tools in many areas of applied and biological physics.
Conventional optical tweezers are based on refractive optics, and they require
excessive auxiliary optical elements to reshape both amplitude and phase, as
well as wavevector and angular momentum of light, and thus impose limitations
to the overall cost and integration of optical systems. Metamaterials provide
both electric and optically induced magnetic response in subwavelength optical
structures, and they are highly beneficial to achieve unprecedented control of
light required for many applications, also opening new opportunities for
optical manipulation. Here, we review the recent advances in the field of
optical tweezers employing the physics and concepts of metamaterials (the
so-called meta-tweezers) and demonstrate that metamaterial structures could not
only advance classical operations with particles, such as trapping,
transporting, and sorting, but they uncover exotic optical forces such as
pulling and lateral forces. Remarkably, apart from manipulation of particles,
metastructures can be powered dynamically by light to realize ingenious
meta-robots. We provide an outlook for future opportunities in this area
ranging from enhanced particle manipulation to meta-robot actuation.
