Actuators

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10 pages, 7187 KiB

Open AccessEditorial

Micromanipulation: A Challenge for Actuation

by Nicola Pio Belfiore

Actuators 2018, 7(4), 85; https://doi.org/10.3390/act7040085 - 3 Dec 2018

Cited by 15 | Viewed by 5888

Abstract

Manipulating micro objects has become an important task in several applications. Actuation is a crucial aspect of micromanipulation because there are physical restrictions which affect actuators’ performances at the micro or nano scale. One way of getting rid of these limitations is the [...] Read more.

Manipulating micro objects has become an important task in several applications. Actuation is a crucial aspect of micromanipulation because there are physical restrictions which affect actuators’ performances at the micro or nano scale. One way of getting rid of these limitations is the use of an appropriate mechanical structure which enhances the elasticity of the material or provides mechanical advantage. This Special Issue of Actuators, which is dedicated to micromanipulation, offers a contribution to the development of some promising methods to actuate a microsystem for micromanipulation. Full article

(This article belongs to the Special Issue Micromanipulation)

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Research

Jump to: Editorial

15 pages, 20826 KiB

Open AccessFeature PaperArticle

Mechanical Response of Four-Bar Linkage Microgrippers with Bidirectional Electrostatic Actuation

by Fabio Botta, Matteo Verotti, Alvise Bagolini, Pierluigi Bellutti and Nicola Pio Belfiore

Actuators 2018, 7(4), 78; https://doi.org/10.3390/act7040078 - 11 Nov 2018

Cited by 11 | Viewed by 6864

Abstract

This paper presents both an experimental and a numerical study concerning the mechanical response of a silicon microgripper with bidirectional electrostatic actuation to externally applied excitations. The experimental set-up is composed of a probe station equipped with mobile probes that apply contact forces. [...] Read more.

This paper presents both an experimental and a numerical study concerning the mechanical response of a silicon microgripper with bidirectional electrostatic actuation to externally applied excitations. The experimental set-up is composed of a probe station equipped with mobile probes that apply contact forces. This part of the investigation aims to test the device’s mechanical resistance, its mobility capability and possible internal contacts during the system deformation. The second part of the paper is dedicated to the study of the free undamped vibrations of the microsystem. Finite Element Analysis (FEA) is carried out to evaluate the system vibration modes. The analysis of the modes are useful to predict possible mechanical interference among floating and anchored fingers of the actuating comb drives. Full article

(This article belongs to the Special Issue Micromanipulation)

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12 pages, 2436 KiB

Open AccessArticle

Recursive Least Squares Filtering Algorithms for On-Line Viscoelastic Characterization of Biosamples

by Paolo Di Giamberardino, Maria Laura Aceto, Oliviero Giannini and Matteo Verotti

Actuators 2018, 7(4), 74; https://doi.org/10.3390/act7040074 - 22 Oct 2018

Cited by 6 | Viewed by 5117

Abstract

The mechanical characterization of biological samples is a fundamental issue in biology and related fields, such as tissue and cell mechanics, regenerative medicine and diagnosis of diseases. In this paper, a novel approach for the identification of the stiffness and damping coefficients of [...] Read more.

The mechanical characterization of biological samples is a fundamental issue in biology and related fields, such as tissue and cell mechanics, regenerative medicine and diagnosis of diseases. In this paper, a novel approach for the identification of the stiffness and damping coefficients of biosamples is introduced. According to the proposed method, a MEMS-based microgripper in operational condition is used as a measurement tool. The mechanical model describing the dynamics of the gripper-sample system considers the pseudo-rigid body model for the microgripper, and the Kelvin–Voigt constitutive law of viscoelasticity for the sample. Then, two algorithms based on recursive least square (RLS) methods are implemented for the estimation of the mechanical coefficients, that are the forgetting factor based RLS and the normalised gradient based RLS algorithms. Numerical simulations are performed to verify the effectiveness of the proposed approach. Results confirm the feasibility of the method that enables the ability to perform simultaneously two tasks: sample manipulation and parameters identification. Full article

(This article belongs to the Special Issue Micromanipulation)

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15 pages, 13040 KiB

Open AccessArticle

Preparing and Mounting Polymer Nanofibers onto Microscale Test Platforms

by Ramesh Shrestha, Sheng Shen and Maarten P. de Boer

Actuators 2018, 7(4), 71; https://doi.org/10.3390/act7040071 - 15 Oct 2018

Cited by 2 | Viewed by 8205

Abstract

Because they can achieve a high degree of molecular chain alignment in comparison with their bulk counterparts, the mechanical and thermal properties of polymer nanofibers are of great interest. However, due to their nanometer-scale size, it is difficult to manipulate, grip, and test [...] Read more.

Because they can achieve a high degree of molecular chain alignment in comparison with their bulk counterparts, the mechanical and thermal properties of polymer nanofibers are of great interest. However, due to their nanometer-scale size, it is difficult to manipulate, grip, and test these fibers. Here, we demonstrate simple repeatable methods to transfer as-drawn fibers to micrometer-scale test platforms where their properties can be directly measured. Issues encountered and methods to minimize measurement artifacts are also discussed. Full article

(This article belongs to the Special Issue Micromanipulation)

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11 pages, 11103 KiB

Open AccessArticle

An Approach to the Extreme Miniaturization of Rotary Comb Drives

by Andrea Veroli, Alessio Buzzin, Fabrizio Frezza, Giampiero De Cesare, Muhammad Hamidullah, Ennio Giovine, Matteo Verotti and Nicola Pio Belfiore

Actuators 2018, 7(4), 70; https://doi.org/10.3390/act7040070 - 11 Oct 2018

Cited by 16 | Viewed by 6843

Abstract

The evolution of microelectronic technologies is giving constant impulse to advanced micro-scaled systems which perform complex operations. In fact, the actual micro and nano Electro-Mechanical Systems (MEMS/NEMS) easily integrate information-gathering and decision-making electronics together with all sorts of sensors and actuators. Mechanical manipulation [...] Read more.

The evolution of microelectronic technologies is giving constant impulse to advanced micro-scaled systems which perform complex operations. In fact, the actual micro and nano Electro-Mechanical Systems (MEMS/NEMS) easily integrate information-gathering and decision-making electronics together with all sorts of sensors and actuators. Mechanical manipulation can be obtained through microactuators, taking advantage of magnetostrictive, thermal, piezoelectric or electrostatic forces. Electrostatic actuation, more precisely the comb-drive approach, is often employed due to its high versatility and low power consumption. Moreover, the device design and fabrication process flow can be simplified by compliant mechanisms, avoiding complex elements and unorthodox materials. A nano-scaled rotary comb drive is herein introduced and obtained using NEMS technology, with an innovative design which takes advantages of the compliant mechanism characteristics. A theoretical and numerical study is also introduced to inspect the electro-mechanical behavior of the device and to describe a new technological procedure for its fabrication. Full article

(This article belongs to the Special Issue Micromanipulation)

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13 pages, 4920 KiB

Open AccessArticle

An Image Analysis Approach to Microgrippers Displacement Measurement and Testing

by Francesco Orsini, Federica Vurchio, Andrea Scorza, Rocco Crescenzi and Salvatore Andrea Sciuto

Actuators 2018, 7(4), 64; https://doi.org/10.3390/act7040064 - 24 Sep 2018

Cited by 13 | Viewed by 4944

Abstract

The number of studies on microgrippers has increased consistently in the past decade, among them the numeric simulations and material characterization are quite common, while the metrological issues related to their performance testing are not well investigated yet. To add some contribution in [...] Read more.

The number of studies on microgrippers has increased consistently in the past decade, among them the numeric simulations and material characterization are quite common, while the metrological issues related to their performance testing are not well investigated yet. To add some contribution in this field, an image analysis-based method for microgrippers displacement measurement and testing is proposed here: images of a microgripper prototype supplied with different voltages are acquired by an optical system (i.e., a 3D optical profilometer) and processed through in-house software. With the aim to assess the quality of the results a systematic approach is proposed for determining and quantifying the main error sources and applied to the uncertainty estimation in angular displacement measurements of the microgripper comb-drives. A preliminary uncertainty evaluation of the in-house software is provided by a Monte Carlo Simulation and its contribution added to that of the other error sources, giving an estimation of the relative uncertainty up to 3.6% at 95% confidence level for voltages from 10 V to 28 V. Moreover, the measurements on the prototype device highlighted a stable behavior in the voltage range from 0 V to 28 V with a maximum rotation of 1.3° at 28 V, which is lower than in previous studies, likely due to differences in system configuration, model, and material. Anyway, the proposed approach is suitable also for different optical systems (i.e., trinocular microscopes). Full article

(This article belongs to the Special Issue Micromanipulation)

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22 pages, 16067 KiB

Open AccessArticle

Scalloping and Stress Concentration in DRIE-Manufactured Comb-Drives

by Silvia Bertini, Matteo Verotti, Alvise Bagolini, Pierliugi Bellutti, Giuseppe Ruta and Nicola Pio Belfiore

Actuators 2018, 7(3), 57; https://doi.org/10.3390/act7030057 - 5 Sep 2018

Cited by 10 | Viewed by 7083

Abstract

In the last decades, microelectromechanical systems have been increasing their number of degrees of freedom and their structural complexity. Hence, most recently designed MEMSs have required higher mobility than in the past and higher structural strength and stability. In some applications, device thickness [...] Read more.

In the last decades, microelectromechanical systems have been increasing their number of degrees of freedom and their structural complexity. Hence, most recently designed MEMSs have required higher mobility than in the past and higher structural strength and stability. In some applications, device thickness increased up to the order of tens (or hundred) of microns, which nowadays can be easily obtained by means of DRIE Bosch process. Unfortunately, scalloping introduces stress concentration regions in some parts of the structure. Stress concentration is a dangerous source of strength loss for the whole structure and for comb-drives actuators which may suffer from side pull-in. This paper presents an analytical approach to characterize stress concentrations in DRIE micro-machined MEMS. The method is based on the linear elasticity equations, the de Saint-Venant Principle, and the boundary value problem for the case of a torsional state of the beam. The results obtained by means of this theoretical method are then compared with those obtained by using two other methods: one based on finite difference discretization of the equations, and one based on finite element analysis (FEA). Finally, the new theoretical approach yields results which are in accordance with the known value of the stress concentration factor for asymptotically null radius notches. Full article

(This article belongs to the Special Issue Micromanipulation)

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9 pages, 10954 KiB

Open AccessArticle

Learning Micromanipulation, Part 2: Term Projects in Practice

by Giovanni Bonciani, Gaetano Biancucci, Simona Fioravanti, Vagif Valiyev and Antonello Binni

Actuators 2018, 7(3), 56; https://doi.org/10.3390/act7030056 - 3 Sep 2018

Cited by 4 | Viewed by 5565

Abstract

This paper describes the activities that have been necessary to design, fabricate, control and test some low-cost test stands independently developed by the students enrolled in the course of Micro-Nano sensors and actuators for the postgraduate course in Industrial Nanotechnologies Engineering of the [...] Read more.

This paper describes the activities that have been necessary to design, fabricate, control and test some low-cost test stands independently developed by the students enrolled in the course of Micro-Nano sensors and actuators for the postgraduate course in Industrial Nanotechnologies Engineering of the University of Rome La Sapienza. The construction and use of these test stands are an essential part of teaching and learning methods whose theoretical bases have been presented in the companion paper (Part 1). Each test stand is composed of a compliant structure and a control system, which consists of a programmable control micro-card equipped with sensors and actuators. The compliant structure consists of a compliant mechanism whose geometry is achieved by scaling some previously developed silicon micromanipuators and microactuators up to the macroscale by a factor of 20. This macroscale model offered a kinesthetic tool to improve the understanding of the original microsystems and their working principles. The original silicon micromechanisms have been previously presented in the literature by the research group after design and deep reactive-ion etching (DRIE) microfabrication. Scaling from micro to macro size was quite easy because the original DRIE masks were bestowed to the students in the form of CAD files. The samples at the macroscale have been fabricated by means of recently available low-cost 3D printers after some necessary modifications of the mask geometry. The purpose of the whole work (Parts 1 and 2) was the improvement of the efficiency of an educational process in the field of microsystem science. By combining the two companion papers, concerning, respectively, the theoretical basis of the teaching methods and the students’ achievements, it is possible to conclude that, in a given class, there may be some preferred activities that are more efficient than others in terms of advancements and satisfaction. Full article

(This article belongs to the Special Issue Micromanipulation)

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9 pages, 599 KiB

Open AccessArticle

Learning Micromanipulation, Part 1: An Approach Based on Multidimensional Ability Inventories and Text Mining

by Gaetano Biancucci, Giovanni Bonciani, Simona Fioravanti, Antonello Binni, Franco Lucchese and Apollonia Matrisciano

Actuators 2018, 7(3), 55; https://doi.org/10.3390/act7030055 - 3 Sep 2018

Cited by 2 | Viewed by 4878

Abstract

In the last decades, an effort has been made to improve the efficiency of high-level and academic education players. Nowadays, students’ preferences and habits are continuously evolving and so the educational institutions deal with important challenges, such as not losing attractiveness or preventing [...] Read more.

In the last decades, an effort has been made to improve the efficiency of high-level and academic education players. Nowadays, students’ preferences and habits are continuously evolving and so the educational institutions deal with important challenges, such as not losing attractiveness or preventing early abandonment during the programs. In many countries, some important universities are public, and so they receive national grants that are based on a variety of factors, on which the teaching efficiency has a great impact. This contribution presents a method to improve students commitment during traditional lessons and laboratory tests. The idea consists in planning some activities according to the students’ learning preferences, which were studied by means of two different approaches. The first one was based on Gardner’s multiple intelligence inventory, which is useful to highlight some peculiar characteristics of the students on the specific educational field. In the second method, direct interviews, voice recognition, and text mining were used to extract some interesting characteristics of the group of students who participated in the projects. The methods were applied in May 2018 to the students attending the course of Micro-Nano Sensors and Actuators for the postgraduate academic program dedicated to Industrial Nanotechnologies Engineering of the University of Rome La Sapienza. The present paper represents the first part of the investigation and it is dedicated essentially to the adopted methods. The second part of the work is presented in the companion paper dedicated to the presentation of the practical project that the students completed before the exam. Full article

(This article belongs to the Special Issue Micromanipulation)

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20 pages, 5373 KiB

Open AccessArticle

The Effects of Structure Thickness, Air Gap Thickness and Silicon Type on the Performance of a Horizontal Electrothermal MEMS Microgripper

by Marija Cauchi, Ivan Grech, Bertram Mallia, Pierluigi Mollicone and Nicholas Sammut

Actuators 2018, 7(3), 38; https://doi.org/10.3390/act7030038 - 15 Jul 2018

Cited by 14 | Viewed by 6536

Abstract

The ongoing development of microelectromechanical systems (MEMS) over the past decades has made possible the achievement of high-precision micromanipulation within the micromanufacturing, microassembly and biomedical fields. This paper presents different design variants of a horizontal electrothermally actuated MEMS microgripper that are developed as [...] Read more.

The ongoing development of microelectromechanical systems (MEMS) over the past decades has made possible the achievement of high-precision micromanipulation within the micromanufacturing, microassembly and biomedical fields. This paper presents different design variants of a horizontal electrothermally actuated MEMS microgripper that are developed as microsystems to micromanipulate and study the deformability properties of human red blood cells (RBCs). The presented microgripper design variants are all based on the U-shape ‘hot and cold arm’ actuator configuration, and are fabricated using the commercially available Multi-User MEMS Processes (MUMPs

^{®}

) that are produced by MEMSCAP, Inc. (Durham, NC, USA) and that include both surface micromachined (PolyMUMPs™) and silicon-on-insulator (SOIMUMPs™) MEMS fabrication technologies. The studied microgripper design variants have the same in-plane geometry, with their main differences arising from the thickness of the fabricated structures, the consequent air gap separation between the structure and the substrate surface, as well as the intrinsic nature of the silicon material used. These factors are all inherent characteristics of the specific fabrication technologies used. PolyMUMPs™ utilises polycrystalline silicon structures that are composed of two free-standing, independently stackable structural layers, enabling the user to achieve structure thicknesses of 1.5

μ

m, 2

μ

m and 3.5

μ

m, respectively, whereas SOIMUMPs™ utilises a 25

μ

m thick single crystal silicon structure having only one free-standing structural layer. The microgripper design variants are presented and compared in this work to investigate the effect of their differences on the temperature distribution and the achieved end-effector displacement. These design variants were analytically studied, as well as numerically modelled using finite element analysis where coupled electrothermomechanical simulations were carried out in CoventorWare

^{®}

(Version 10, Coventor, Inc., Cary, NC, USA). Experimental results for the microgrippers’ actuation under atmospheric pressure were obtained via optical microscopy studies for the PolyMUMPs™ structures, and they were found to be conforming with the predictions of the analytical and numerical models. The focus of this work is to identify which one of the studied design variants best optimises the microgripper’s electrothermomechanical performance in terms of a sufficient lateral tip displacement, minimum out-of-plane displacement at the arm tips and good heat transfer to limit the temperature at the cell gripping zone, as required for the deformability study of RBCs. Full article

(This article belongs to the Special Issue Micromanipulation)

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19 pages, 7345 KiB

Open AccessArticle

Polymer Microgripper with Autofocusing and Visual Tracking Operations to Grip Particle Moving in Liquid

by Ren-Jung Chang and Yu-Cheng Chien

Actuators 2018, 7(2), 27; https://doi.org/10.3390/act7020027 - 11 Jun 2018

Cited by 4 | Viewed by 5481

Abstract

A visual-servo automatic micromanipulating system was developed and tested for gripping the moving microparticle suspended in liquid well. An innovative design of microgripper integrated with flexible arms was utilized to constrain particles in a moving work space. A novel focus function by non-normalized [...] Read more.

A visual-servo automatic micromanipulating system was developed and tested for gripping the moving microparticle suspended in liquid well. An innovative design of microgripper integrated with flexible arms was utilized to constrain particles in a moving work space. A novel focus function by non-normalized wavelet entropy was proposed and utilized to estimate the depth for the alignment of microgripper tips and moving particle in the same focus plane. An enhanced tracking algorithm, which is based on Polar Coordinate System Similarity, incorporated with template matching, edge detection method, and circular Hough Transform, was implemented. Experimental tests of the manipulation processes from moving gripper to tracking, gripping, transporting, and releasing 30–50 μm Polystyrene particle in 25 °C water were carried out. Full article

(This article belongs to the Special Issue Micromanipulation)

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16 pages, 9583 KiB

Open AccessArticle

Innovative Silicon Microgrippers for Biomedical Applications: Design, Mechanical Simulation and Evaluation of Protein Fouling

by Cristina Potrich, Lorenzo Lunelli, Alvise Bagolini, Pierluigi Bellutti, Cecilia Pederzolli, Matteo Verotti and Nicola Pio Belfiore

Actuators 2018, 7(2), 12; https://doi.org/10.3390/act7020012 - 24 Mar 2018

Cited by 31 | Viewed by 7701

Abstract

The demand of miniaturized, accurate and robust micro-tools for minimally invasive surgery or in general for micro-manipulation, has grown tremendously in recent years. To meet this need, a new-concept comb-driven microgripper was designed and fabricated. Two microgripper prototypes differing for both the number [...] Read more.

The demand of miniaturized, accurate and robust micro-tools for minimally invasive surgery or in general for micro-manipulation, has grown tremendously in recent years. To meet this need, a new-concept comb-driven microgripper was designed and fabricated. Two microgripper prototypes differing for both the number of links and the number of conjugate surface flexure hinges are presented. Their design takes advantage of an innovative concept based on the pseudo-rigid body model, while the study of microgripper mechanical potentialities in different configurations is supported by finite elements’ simulations. These microgrippers, realized by the deep reactive-ion etching technology, are intended as micro-tools for tissue or cell manipulation and for minimally invasive surgery; therefore, their biocompatibility in terms of protein fouling was assessed. Serum albumin dissolved in phosphate buffer was selected to mimic the physiological environment and its adsorption on microgrippers was measured. The presented microgrippers demonstrated having great potential as biomedical tools, showing a modest propensity to adsorb proteins, independently from the protein concentration and time of incubation. Full article

(This article belongs to the Special Issue Micromanipulation)

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14 pages, 17239 KiB

Open AccessArticle

Modeling a Pull-In Instability in Micro-Machined Hybrid Contactless Suspension

by Kirill V. Poletkin and Jan G. Korvink

Actuators 2018, 7(1), 11; https://doi.org/10.3390/act7010011 - 20 Mar 2018

Cited by 13 | Viewed by 7884

Abstract

A micro-machined hybrid contactless suspension, in which a conductive proof mass is inductively levitated within an electrostatic field, is studied. This hybrid suspension has the unique capability to control the stiffness, in particular along the vertical direction, over a wide range, which is [...] Read more.

A micro-machined hybrid contactless suspension, in which a conductive proof mass is inductively levitated within an electrostatic field, is studied. This hybrid suspension has the unique capability to control the stiffness, in particular along the vertical direction, over a wide range, which is limited by a pull-in instability. A prototype of the suspension was micro-fabricated, and the decrease of the vertical component of the stiffness by a factor of 25% was successfully demonstrated. In order to study the pull-in phenomenon of this suspension, an analytical model was developed. Assuming quasi-static behavior of the levitated proof mass, the static and dynamic pull-in of the suspension was comprehensively studied, also yielding a definition for the pull-in parameters of the hybrid suspension. Full article

(This article belongs to the Special Issue Micromanipulation)

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