In this paper, we study energy harvesting from the beating of a biomimetic fish tail using ionic polymer-metal composites. The design of the biomimetic tail is based on carangiform swimmers and is specifically inspired by the morphology of the heterocercal tail of thresher sharks. The tail is constituted of a soft silicone matrix molded in the form of the heterocercal tail and reinforced by a steel beam of rectangular cross section. We propose a modeling framework for the underwater vibration of the biomimetic tail, wherein the tail is assimilated to a cantilever beam with rectangular cross section and heterogeneous physical properties. We focus on base excitation in the form of a superimposed rotation about a fixed axis and we consider the regime of moderately large-amplitude vibrations. In this context, the effect of the encompassing fluid is described through a hydrodynamic function, which accounts for inertial, viscous and convective phenomena. The model is validated through experiments in which the base excitation is systematically varied and the motion of selected points on the biomimetic tail tracked in time. The feasibility of harvesting energy from an ionic polymer-metal composite attached to the vibrating structure is experimentally and theoretically assessed. The response of the transducer is described using a black-box model, where the voltage output is controlled by the rate of change of the mean curvature. Experiments are performed to elucidate the impact of the shunting resistance, the frequency of the base excitation and the placement of the ionic polymer-metal composite on energy harvesting from the considered biomimetic tail.

An atlas of 98 microgrippers that recently appeared in Literature is herein presented by using four different forms: (a) a restyled layout of the original mechanical structure, (b) its corresponding pseudorigid body model (PRBM), (c) its kinematic chain, and finally, (d) its related graph. Homogeneity in functional sketching (a) is assumed to be greatly helpful to understand how these grippers work and what are the most significant differences between them. Therefore, a unified and systematic set of aesthetics and proportionality criteria have been adopted. Analogously, unified criteria for obtaining pseudorigid (b), kinematic (c), and graph (d) representations have been also used, which made the atlas easy to be read and inspected. The distinction among lumped and distributed compliance has been also accepted to develop the structure of the atlas. A companion paper has been prepared to present a survey on the variety of operational strategies that are used in these microgrippers

The fabrication of a novel class of microgrippers is\ud demonstrated by means of bulk microelectromechanical systems (MEMS) technology using silicon on insulator wafer substrates and deep reactive ion etching. Hard masking is implemented to maximize the selectivity of the bulk etching using sputtered aluminum and aluminum–titanium thin films. The microroughness problem related to the use of metal mask is addressed by testing different mask combinations and etching parameters. The O2 flow, SF6 pressure, wafer temperature, and bias power are examined, and the effect of each parameter on micromasking is assessed. Sidewall damage associated with the use of a metal mask is eliminated by interposing a dielectric layer between silicon substrate and metal mask. Dedicated combdrive anchors are implemented to etch safely both silicon sides down to the buried oxide, and to preserve the wafer integrity until the final wet release of the completed structures. A first set of complete devices is realized and tested under electrical actuation

This article provides an overview of the operational strategies adopted in microgrippers design. The review covers microgrippers recently proposed in Literature, some of which have been systematically presented in a companion paper, where their topological, kinematic, and structural characteristics are discussed. In the present contribution, the prevalent actuation methods and the operational aspects are discussed: the tip displacement, the tip force, the actuation voltage, and the amplification factor are the reference parameters that are adopted to compare the different types of actuation and operational strategies. In addition, the control strategies and control algorithms currently adopted are reviewed

This paper presents a new concept flexure hinge for MEMS applications and reveals how to design, construct, and experimentally test. This hinge combines a curved beam, as a flexible element, and a pair of conjugate surfaces, whose contact depends on load conditions. The geometry is conceived in such a way that minimum stress conditions are maintained within the flexible beam. A comparison of the new design with the other kind of revolute and flexible joints is presented. Then, the static behavior of the hinge is analyzed by means of a theoretical approach, based on continuum mechanics, and the results are compared to those obtained by means of finite element analysis (FEA) simulation. A silicon hinge prototype is also presented and the construction process, based on single step lithography and reactive ion etching (RIE) technology, is discussed. Finally, a crucial in–SEM experiment is performed and the experimental results are interpreted through the theoretical models.