  Controllable rotation of micro-/nano-objects provides tremendous
opportunities for cellular biology, three-dimensional (3D) imaging, and
micro/nanorobotics. Among different rotation techniques, optical rotation is
particularly attractive due to its contactless and fuel-free operation.
However, optical rotation precision is typically impaired by the intrinsic
optical heating of the target objects. Optothermal rotation, which harnesses
light-modulated thermal effects, features simpler optics, lower operational
power, and higher applicability to various objects. In this Feature Article, we
discuss the recent progress of optothermal rotation with a focus on work from
our research group. We categorize the various rotation techniques based on
distinct physical mechanisms, including thermophoresis, thermoelectricity,
thermo-electrokinetics, thermo-osmosis, thermal convection, and
thermo-capillarity. Benefiting from the different rotation modes (i.e.,
in-plane and out-of-plane rotation), diverse applications in single-cell
mechanics, 3D bio-imaging, and micro/nanomotors are demonstrated. We conclude
the article with our perspectives on the operating guidelines, existing
challenges, and future directions of optothermal rotation.
