Special Issue "Advances in Actuators"

Guest Editor
Prof. Dr. Sang-Gook Kim
Massachusetts Institute of Technology, Department of Mechanical Engineering, Room 1-310, 77 Massachusetts Ave., Cambridge, MA 02139, USA
Website: http://mit.edu/micronanosystems/www/
E-Mail:
Interests: nanomanufacturing; carbon nanotube growth and assembly; PZT MEMS; energy harvesting; non-lithographic MEMS

Dear Colleagues,

Actuator is an essential component of electromechanical systems which converts electrical energy into mechanical work. The growing demand for actuators at multi-scales (macro, meso, micro and nano) and in emerging areas such as biomedical applications and micro-autonomous systems requires more robust, efficient and scalable actuator technologies. This special issue of Sensors entitled, “Advances in Actuators,” aims to report recent emerging actuator technologies in response to these demands such as muscle-inspired actuators, design and manufacturing of thin film piezoelectric and shape memory actuators and electro-active polymer actuators. We invite researchers and scientists to submit their latest results and developments for the following topics, but not limited to:

• Artificial muscle actuators
• In-plane linear micro actuators
• Large strain micro actuators
• Design and fabrication of nano actuators
• Multi-scale assembly of micro/nano/meso actuators
• Piezoelectric actuators
• Conducting polymer and dielectric elastomer actuators
• Shape memory actuators
• Low-power actuators
• Novel control technology for emerging actuators (see keywords below)

Prof. Dr. Sang-Gook Kim
Guest Editor

Submission

• artificial muscle actuators
• in-plane linear micro actuators
• large strain micro actuators
• design and fabrication of nano actuators
• multi-scale assembly of micro/nano/meso actuators
• piezoelectric actuators
• conducting polymer and dielectric elastomer actuators
• shape memory actuators
• low-power actuators
• novel control technology for emerging actuators

Title: Ionic Polymer Metal Composites (IPMCs) as Soft Biomimetic Actuators and Sensors - A Review
Author: Mohsen Shahinpoor
Affiliation: Biomedical Engineering Laboratory, Mechanical Engineering Department, University of Maine Orono. ME, 04469 USA; E-Mail: mohsen.shahinpoor@maine.edu
Abstract: This comprehensive review paper covers advances made in connection with Ionic Polymer Metal Composites (IPMCs) as distributed biomimetic nanosensors, nanoactuators, nanorobots and artificial muscles. A review of the fundamental properties and characteristics of IPMCs will first be presented. This summary will include descriptions of the basic materials' molecular structure and subsequent procedure to manufacture the basic material for electroless/chemical plating and electroactivation. Further described are chemical molecular plating technologies to make IPMCs, nanotechnologies of manufacturing and trapping of nanoparticles, SEM, TEM, SPM and AFM characterization of IPMCs, biomimetic sensing and actuation characterization techniques, electrical characterization and equivalent circuit modeling of IPCNCs as electronic materials.
A review of current modeling is also presented that covers the phenomenological model of the underlying sensing and actuation mechanisms based on linear irreversible thermodynamics with two driving forces, an electric field and a solvent pressure gradient and two fluxes, electric current density and the ionic+solvent flux.
Keywords: ionic polymers; IPMCs; biomimetic; actuators; sensors

Type of Paper: Article
Title: Sensors for Hemodialysis: Improving tolerance and Efficiency in the Dialysis Treatment
Authors: Elena Mancini, Juri Piattoni, Antonio Bellasi and Antonio Santoro
Affiliation: Nephrology, Dialysis, Hypertension Unit Policlinico S.Orsola-Malpighi, Bologna,Italy; E-Mail: elena.mancini@aosp.bo.it
Abstract: The physicians’ attention to the problems of the hemodynamic tolerance as well as to the efficiency of the dialysis treatment has greatly increased over the last two decades due to the progressive increase in age and high degree of comorbidity of the patients receiving dialysis, especially the cardiovascular pathology and diabetes that hamper an efficient hemodynamic response. Technological research has tried to satisfy this need, by realising a number of devices aimed at a non-invasive, continuous, online monitoring of the different parameters, both of a hemodynamic and of a biochemical kind. An essential pre-requisite for reaching these objectives is that of disposing of adequate measurement devices and “sensors” for continuous measures during the dialysis sessions. Thus, besides a high degree of reliability and the continuity and accuracy of the measure, essential characteristics are relative simplicity of use, sterility and biocompatibility (for the sensors that come into direct contact with the blood), the possibility to interface the measurement system with a computer and, lastly, an acceptable cost that will not further inflate dialysis treatment costs that are already high enough. But the indispensable pre-requisite for a sensor to be used in hemodialysis is its absolute non-invasiveness and utmost tolerability on the part of the patient. Some devices for continuous hemodynamic or biochemical monitoring can be implemented in the dialysis instrumentation with a view to preventing cardiocirculatory instability (acute hypotension, arrhythmias) or controlling and improving the dialysis efficiency. The paper will review all the types of electronic, non invasive sensors implemented in dialysis up to now, mainly in a technical view, the operative characteristics, the applications and the clinical experiences.

Type of Paper: Review
Title: Sensing and Tactile Artificial Muscles from Reactive Materials
Authors: L. Valero ², J. Arias-Pardilla ¹, J. Cauich-Rodríguez ², M. Smit ² and T.F. Otero ¹
Affiliations: ¹ Centre for Electrochemistry and Intelligent Materials (CEMI), Universidad Politécnica de Cartagena, ETSII, E- 30203, Cartagena, Spain; E-Mail: toribio.fotero@upct.es
² Materials Department, Centro de Investigación Científica de Yucatán (CICY), C.P. 97219 Mérida, Mexico
Abstract: Films of conducting polymers used as working electrodes in electrolytes can be oxidized and reduced in a reverse way. Any intermediate oxidation state determines an electrochemical equilibrium. Any chemical or physical variable acting on the equilibrium modifies the equilibrium potential, which acts as a sensor of the variable. The working potential evolution of polypyrrole/DBSA films, oxidized or reduced under constant currents, also changes as a function of the working conditions: electrolyte concentration, temperature or mechanical stress. During oxidation the reactive material is a sensor of the ambient, the consumed electrical energy being the sensing magnitude. Devices based on any of the electrochemical properties of conducting polymers must act simultaneously as sensors of the working conditions. Artificial muscles, as electrochemical actuators constituted by reactive materials, respond to the ambient conditions during actuation. In this way, they ca be used as actuators, sensing the surrounding conditions during actuation. Actuating and sensing signals are simultaneously included by the same two connecting wires.

Type of Paper: Review
Title: Magnetostrictive Iron-Gallium Alloy Actuators and Sensors
Authors: Jayasimha Atulaismha ¹ and Alison B. Flatau ²
Affiliations: ¹ Department of Mechanical Engineering, Virginia Commonwealth University, Richmond VA 23284, USA; E-Mail:
jatulasimha@vcu.edu (J.A.)
² Department of Aerospace Engineering, University of Maryland, College Park MD 20742, USA; E-Mail: aflatau@umd.edu (A.B.F.)
Abstract: A unique combination of low hysteresis, moderate magnetostriction at low magnetic fields, good tensile strength, machinability and recent progress in commercially viable methods of processing Iron-Gallium alloys make them well poised for actuator and sensing applications. This review article starts with the historical development of magnetostrictive materials and basic principles behind the actuation and sensing behavior of magnetostrictive materials. This is followed by addressing challenges specific to the characterization and processing of FeGa alloys and state-of the-art in modeling their actuation and sensing behavior. Finally, some novel devices that employ this material as an actuator or a sensor are discussed.

Type of Paper: Review
Title: Quantitative Modeling of Coupled Piezo-Elastodynamic Behavior of Piezoelectric Actuators for Structural Health Monitoring
Authors: Guoliang Huang¹, Fei Song ² and Xiaodong Wang³
Affiliations: ¹ Department of Systems Engineering, University of Arkansas at Little Rock, Little Rock, AR, USA; E-Mail: glhuang@ualr.edu
² Department of Applied Science, University of Arkansas at Little Rock, Little Rock, AR, USA; E-Mail: fxsong@ualr.edu
³ Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta, Canada; E-Mail: xiaodong.wang@ualberta.ca
Abstract: Elastic waves, especially guided waves, generated by a piezoelectric actuator/sensor system, have shown great potential for the health monitoring of advanced aerospace, nuclear, and automotive structures in recent decades. Piezoelectric materials function as both actuators and sensors in these applications by taking advantaging of direct and converse piezoelectric effects. One of the most fundamental issues surrounding the effective use of surface-bonded piezoelectric actuators in these smart structures is the quantitative evaluation of the generated elastic wave propagation by considering the coupled piezo-elastodynamic behavior. This paper presents a review of the development of analytical approaches for the computational modeling of acoustic, elastodynamic, and coupled piezoelectric and ultrasonic wave phenomenon related to the structural health monitoring. Accurate characterization of the coupled interfacial stress between the actuator and the host medium is the key issue for this problem. Recent investigations on analytical modeling of the coupled dynamic behavior of the piezoelectric actuator bonded to different elastic media and the applications for structural health monitoring are also discussed.
Keywords: elastic waves; coupled dynamic behavior; structural health monitoring; piezoelectric actuators; quantitative modeling