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.

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.

Although tissue and cell manipulation nowadays is a common task in biomedical analysis, there are still many different ways to accomplish it, most of which are still not sufficiently general, inexpensive, accurate, efficient or effective. Several problems arise both for in vivo or in vitro analysis, such as the maximum overall size of the device and the gripper jaws (like in minimally-invasive open biopsy) or very limited manipulating capability, degrees of freedom or dexterity (like in tissues or cell-handling operations). This paper presents a new approach to tissue and cell manipulation, which employs a conceptually new conjugate surfaces flexure hinge (CSFH) silicon MEMS-based technology micro-gripper that solves most of the above-mentioned problems. The article describes all of the phases of the development, including topology conception, structural design, simulation, construction, actuation testing and in vitro observation. The latter phase deals with the assessment of the function capability, which consists of taking a series of in vitro images by optical microscopy. They offer a direct morphological comparison between the gripper and a variety of tissues.

Magnetorheological (MR) fluids are capable of manifesting a rheological behaviour change by means of a magnetic field application and can be employed in many complex systems in many technical fields. One successful example is their use in the development of dampers: magnetorheological dampers (MRDs) are widespread in vibration control systems, as well as civil engineering applications (i.e., earthquake or seismic protection), impact absorption and vibration isolation technology in industrial engineering, and advanced prosthetics in biomedical fields. In the past, many studies have been conducted on MRDs modeling and characterization, but they have usually been focused more on the theoretical models than on the experimental issues. In this work, an overview of both of them is proposed. In particular, after an introduction to the physics of the magnetorheological effect, a short review of the main mathematical models of MRDs is proposed. Finally, in the second part of this study an overview of the main issues that occur in MRDs experimental characterization is reported and discussed.

The fabrication of a novel class of microgrippers is 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 comb-drive 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.