Micro/Nano Robot is an intelligent and efficient microrobot that can perform specific tasks under the influence of external stimuli. Depending on the application scenarios, the microrobot can adaptively transform into appropriate functional forms under different external stimuli, thus perfectly matching the needs. To date, microbots have been widely used in targeted therapy, drug delivery, tissue engineering, environmental remediation, and other fields. Although the applications of microrobots are promising, there are only a few reviews that can focus on the preparation methods and driving mechanisms. Therefore, it is necessary to outline the current status of the development of these microrobots in order to provide some new insights for the further development of the field. Therefore, this paper reviews the research progress of microrobots in terms of preparation methods, stimulus response mechanisms and applications, and highlights the applicability of different preparation methods and stimulus types. Finally, the current challenges faced by microrobots are highlighted and possible solutions are proposed to facilitate the practical application of microrobots.

Microscale swimmers have to face the dominance of viscous forces over inertial forces, the so-called low Reynolds number (hereafter Re) regime. The undulatory motion of an elastic tail is one of the few possible mechanisms for the self-propulsion of microswimmers in the particular conditions of low Re. Instead of using a complex arrangement of multiple actuators along the body of the swimmer, this work studies the propulsion of a swimming microrobot that is able to generate a non-reciprocal motion by moving a passive elastic tail with non-uniform properties using only a single actuator located at its head. A simulation model is developed in MATLAB to evaluate the effect of different mass and elasticity distributions in the tail on the microrobot propulsion. The results are used to observe the undulating motion of the tail and to optimize the design of the robotic microswimmers in terms of efficiency.