We introduce the modelling and control of a rolling microrobot. The microrobot is capable of manipulating micro-objects through the use of a magnetic visual control system. This system consists of a rod-shaped microrobot, a magnetic actuation system and a visual control system. Motion of the rolling microrobot on a supporting surface is induced by a rotating magnetic field. As the robot is submerged in a liquid this motion creates a rising flow in front, a sinking flow behind, and a vortex above the robot, thus enabling non-contact transportation of micro-objects. Besides this fluid-vortex approach, the microrobot is also able to manipulate micro-objects via a pushing strategy. We present the design and modelling of the 50×60×300 μm micro-agent, the visual control system, and an experimental analysis of the micromanipulation and control methods.

In this paper, we present a holistic system for automating the motion of a rolling microrobot for protein crystal harvesting. The RodBot, which was introduced in previous work, is able to perform noncontact manipulation of microscopic objects such as fragile crystals by trapping them in an induced vortex fluid flow. Here, we are concerned with navigating the RodBot autonomously in a liquid environment containing obstacles such as crystals. A literature review shows existing approaches to untethered microrobot control are limited and cluttered environments are often not considered. We demonstrate real-time tracking of the RodBot and surrounding obstacles, kinematic obstacle-free path planning, and nonholonomic path following. The system was evaluated in qualitative and quantitative experiments, shows satisfactory performance, and presents itself as a first step towards fully automated crystal harvesting.

In this work, a magnetic visual control system for automated protein crystal harvesting is proposed. The system consists of a rod-shaped microrobot, a magnetic actuation system and a visual control system. A rotating magnetic field induces the microrobot to roll on the supporting surface, thereby creating a vortex in a liquid environment. This vortex enables the robot to trap and transport even delicate objects in a non-contact manner to a pre-defined position. We present the micro-agent, the actuation system and the visual control system to achieve this automated procedure.

This paper presents a new generation of wireless resonant magnetic microactuator (WRMMA) type microrobot, named PolyMite. A polymer is used as a spring material in the design of the PolyMite. Compared with the previous generation of such devices, the use of a polymer, i.e., SU-8, as a spring material enables the design of a stable spring system without a significant increase in stiffness. A speed of over 20 mm/s (40 body lengths per second) was measured when the PolyMite was driven in air. Micromanipulation abilities of the PolyMites in wet environments have also been demonstrated. The agents were capable of transporting microobjects such as light polystyrene beads and heavier glass beads in water. The large output force, remote actuation, and biocompatible outer surface (SU-8 and gold) make the PolyMite an exciting candidate for biomedical applications.

We present a class of Wireless Resonant Magnetic Microactuator (WRMMA) that integrates a polymer spring/body structure with electroplated ferromagnetic masses. The new devices, which we call PolyMites as they are derived from our previous MagMites, are simpler, faster and cheaper to fabricate than the MagMite. Like their predecessor, they are capable of moving on planar surfaces in dry and wet environments. Their improved biocompatibility also extends their potential for biological applications. PolyMites are 500 μm in diameter and 55 μm in height. In air they have attained a speed of 13 mm/s, approximately 26 body lengths per second. PolyMites are capable of micromanipulation on a surface, which is demonstrated by pushing and releasing micro-objects such as polystyrene beads in water.