An overview of multiple DoF magnetic actuated micro-robots

Abstract

This paper reviews the state of the art of untethered, wirelessly actuated and controlled micro-robots. Research for such tools is being increasingly pursued to provide solutions for medical, biological and industrial applications. Indeed, due to their small size they offer both high velocity, and accessibility to tiny and clustered environments. These systems could be used for in vitro tasks on lab-on-chips in order to push and/or sort biological cells, or for in vivo tasks like minimally invasive surgery and could also be used in the micro-assembly of microcomponents. However, there are many constraints to actuating, manufacturing and controlling micro-robots, such as the impracticability of on-board sensors and actuators, common hysteresis phenomena and nonlinear behavior in the environment, and the high susceptibility to slight variations in the atmosphere like tiny dust or humidity. In this work, the major challenges that must be addressed are reviewed and some of the best performing multiple DoF micro-robots sized from tens to hundreds µm are presented. The different magnetic micro-robot platforms are presented and compared. The actuation method as well as the control strategies are analyzed. The reviewed magnetic micro-robots highlight the ability of wireless actuation and show that high velocities can be reached. However, major issues on actuation and control must be overcome in order to perform complex micro-manipulation tasks.

Uncalibrated Visual Servo Control of Magnetically Actuated Microrobots in a Fluid Environment

“…Tetherless microrobot actuation has been achieved using a number of different power delivery methods including optical [2], electrostatic [3], thermal [4], ultrasonic [5] and electromagnetic [6]. A review of propulsion methods specific to swimming microrobots medical applications is given in [7].…”

A More General Capillary Adhesion Model Including Shape Index: Single-Asperity and Multi-Asperity Cases

“…, [2] where γ is the liquid-vapor surface tension, v is the molar volume of the liquid, k B is the Boltzmann's constant, T is the absolute temperature, and p/p s is the relative humidity. γv/(k B T) = 0.54 nm for water at room temperature.…”

Simulation and experiments on magnetic microforces for magnetic microrobots applications

“…A constant current of 0.4A is applied to the coil through a voltage generator and a power-amplification circuit. This is a typical value for that setup [5]. The signal generator provides a positive square wave signal of 500mV amplitude and 1 Hz frequency.…”

“…This technique has thus received a lot of attentions. In recent years, several magnetic microrobots and corresponding driving setups have been developed [5]. Mag-μBot was developed in Carnegie Mellon University, and it is driven by three pairs of coils [6].…”