In this work, the design and development of an integrated platform for the steering of swimming microrobot is reported. The system consists of: a near-spherical soft and buoyant magnetic microrobot (with a diameter of about 500 μm) conceived for operation in liquid; a wireless magnetic steering system, including a compact magnetic field generator based on two pairs of Helmholtz and Maxwell coils; an electronic system for their driving; a control software; a joypad physical user interface; and, the micro-arena as working environment. The platform design fulfills the requirements for the “Mobility Task” of the 2011 NIST Mobile Microrobotics Challenge. The results obtained from preliminary validation experiments confirm that the microrobots can move in a fully controlled way, successfully accomplishing an intricate eight-shape path, as required, in the water filled micro-arena. In particular we achieved a maximum average speed of 0.71 mm/s and an exceptionally smooth motion.

A novel approach for the design of magnetically-propelled microrobots is proposed as an effective solution for swimming in a liquid medium. While intrinsic neutral buoyancy of a microrobot per se simplifies propulsion in the liquid environments, softness makes it compliant with delicate environments, such as the human body, thus guaranteeing a safe interaction with soft structures. With this aim, two groups of soft microrobots with paramagnetic and ferromagnetic behaviors were designed, fabricated and their features were experimentally analyzed. In agreement with the theoretical predictions, in the performed trials the ferromagnetic microrobots showed orientation capabilities in response to the magnetic field that could not be achieved by the paramagnetic one. Moreover, it was observed that the ferromagnetic microrobot could reach higher speed values (maximum value of 0.73 body length/s) than the paramagnetic prototype.

Polymeric ultra-thin films, also called nanosheets, show peculiar properties in terms of thickness, flexibility and chemical structure. For these reasons, they were proposed as nanoplasters for localized drug release or as a new solution for closing endoluminal surgical wounds. This paper presents the fabrication and characterization of free-standing nanosheets loaded with iron oxide nanoparticles, which can be manipulated in liquid environment by means of magnetic fields. A theoretical model of magnetic manipulation of the nanosheet is proposed and validated by dragging the film with a permanent magnet mounted on an industrial robotic arm. Controlling the magnetic sheet in liquid environment represents a first step towards the application of these nanostructures as free-standing carriers to be released and magnetically controlled in endoluminal surgery or as plasters with nanometric thickness to be delivered in situ on surgical incisions. Furthermore, these magnetic nanofilms can be adapted and used as micro and nanocomponents for the design of a novel generation of magnetic actuated polymeric microrobots.