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This article presents the design, optimization, and testing of a new rotating electromagnetic field generation system for actuating magnetic microrobots. Its unique feature lies in that the proposed six-coil electromagnetic actuation system produces a uniform rotating magnetic field with a large 3-D workspace, which is enabled by conducting an architectural optimization of the system in consideration of both electric issues and geometry constraints. To maintain a low working temperature, each coil is fabricated with silicone grease for filling the gap among the copper wires and integrated with a water cooling fan for reducing the effect of coil heating. An analytical model is established to determine the dominant structural parameters, which are optimally tuned by resorting to genetic algorithm (GA) to achieve the best actuation performance. A prototype magnetic field generation system is developed for experimental testing. Experimental studies are carried out by driving various magnetic microrobots, including helical microswimmers and microparticles. Results indicate that the developed system can effectively actuate the microrobots with precision motion tracking, validating the effectiveness of the developed rotating magnetic field generation system. [ABSTRACT FROM AUTHOR]

This article presents the design, fabrication, and testing of a novel piezoelectric energy harvester. Its unique feature is that a single piezoelectric stack is used for harvesting the energy from two-directional excitation in vertical directions. To accept the input forces in two directions, a flexure-based two-stage force amplifier is integrated with a conical transmission mechanism and a sliding guiding mechanism. An analytical model is established to predict the force amplification ratio of the proposed energy harvester. In order to maximize the output performance of the energy harvester, the dominant parameters of the mechanism are determined, which are optimally designed by resorting to a genetic algorithm. A prototype energy harvester is fabricated for experimental testing. Experimental results indicate that the developed harvester exhibits the advantages of high safety factor, large force amplification ratio, and compact size. It can provide the maximum average output power density of over 286.70 kW $\cdot$ m $^{-3}$ from 10-N force excitation in two directions. [ABSTRACT FROM AUTHOR]