Special Issue "Biomedical Applications of Shape Memory Alloys"

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A special issue of Journal of Functional Biomaterials (ISSN 2079-4983).

Deadline for manuscript submissions: closed (31 March 2015)

Special Issue Editors

Guest Editor
Prof. Dr. Tony Anson

Experimental Techniques Centre, Brunel University, Kingston Lane, Uxbridge UB8 3PH, UK
Phone: +44 1895 267833
Interests: biological-synthetic material interface; binary; ternary; quaternary SMA’s; minimally invasive therapies; orthopaedic implants; stents; smart implants
Guest Editor
Prof. Dr. Lorenza Petrini

Department of Civil and Environmental Engineering, Laboratory of Biological Structure Mechanics, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano
Interests: innovative materials, in particular shape memory alloys: development and implementation of material constitutive models; mechanics characterization of materials and devices for biomechanical applications. biomechanics: modelling of minimally-invasive vascular surgeries, of orthodontic and endodontic appliances. design and optimization of innovative devices as biodegradable magnesium stents

Special Issue Information

Dear Colleagues,

Shape Memory Alloys (SMA's) have been widely adopted in the biomedical fields. They are particularly relevant to cardiovascular, orthopaedic, general surgery, and other interventional approaches: prosthetic devices that exploit SMA properties are routinely used in clinical practice. However, many issues still exist; these concern the optimization of functional performance, manufacturing processes, mechanical behavior, biomaterial properties, and the development of relevant computational methods that are able to define behavior.

Of particular interest is the study of fatigue behavior and the potential risk of fracture: equally, the analysis and correlation between manufacturing processes and micro-structural properties with the development of numerical models that are able to define device life-cycles from raw material to final product design are also important.

The development of innovative devices at different scales is an example of one of the most debated arguments relating to the biomedical applications of SMA. This Special Issue aims to give a perspective of the most recent research in the field and welcomes both academic and industrial points of view. Experimental and numerical studies relating to shape memory materials and devices are particularly welcome.

Lorenza Petrini
Tony Anson
Guest Editors

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Journal of Functional Biomaterials is an international peer-reviewed Open Access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 300 CHF (Swiss Francs). English correction and/or formatting fees of 250 CHF (Swiss Francs) will be charged in certain cases for those articles accepted for publication that require extensive additional formatting and/or English corrections.

Published Papers (5 papers)

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Research

Open AccessArticle An Efficient Finite Element Framework to Assess Flexibility Performances of SMA Self-Expandable Carotid Artery Stents
J. Funct. Biomater. 2015, 6(3), 585-597; doi:10.3390/jfb6030585
Received: 28 April 2015 / Revised: 15 June 2015 / Accepted: 10 July 2015 / Published: 14 July 2015
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Abstract
Computer-based simulations are nowadays widely exploited for the prediction of the mechanical behavior of different biomedical devices. In this aspect, structural finite element analyses (FEA) are currently the preferred computational tool to evaluate the stent response under bending. This work aims at [...] Read more.
Computer-based simulations are nowadays widely exploited for the prediction of the mechanical behavior of different biomedical devices. In this aspect, structural finite element analyses (FEA) are currently the preferred computational tool to evaluate the stent response under bending. This work aims at developing a computational framework based on linear and higher order FEA to evaluate the flexibility of self-expandable carotid artery stents. In particular, numerical simulations involving large deformations and inelastic shape memory alloy constitutive modeling are performed, and the results suggest that the employment of higher order FEA allows accurately representing the computational domain and getting a better approximation of the solution with a widely-reduced number of degrees of freedom with respect to linear FEA. Moreover, when buckling phenomena occur, higher order FEA presents a superior capability of reproducing the nonlinear local effects related to buckling phenomena. Full article
(This article belongs to the Special Issue Biomedical Applications of Shape Memory Alloys)
Open AccessArticle Modeling Permanent Deformations of Superelastic and Shape Memory Materials
J. Funct. Biomater. 2015, 6(2), 398-406; doi:10.3390/jfb6020398
Received: 1 April 2015 / Revised: 25 May 2015 / Accepted: 28 May 2015 / Published: 11 June 2015
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Abstract
In this paper we propose a modification of the polycrystalline shape memory alloy constitutive model originally proposed by Souza. By introducing a transformation strain energy with two different hardening coefficients, we are able to take into account the effect of the martensitic [...] Read more.
In this paper we propose a modification of the polycrystalline shape memory alloy constitutive model originally proposed by Souza. By introducing a transformation strain energy with two different hardening coefficients, we are able to take into account the effect of the martensitic transformation of unfavorably oriented grains occurring after the main plateau. By choosing a proper second hardening coefficient, it is possible to reproduce the correct stress strain behavior of the material after the plateau without the need of introducing a much smaller Young modulus for martensite. The proposed modification is introduced in the model comprising permanent deformation effects. Model results for uniaxial stress tests are compared to experimental results showing good agreement. Full article
(This article belongs to the Special Issue Biomedical Applications of Shape Memory Alloys)
Open AccessArticle Applications of Shape Memory Alloys for Neurology and Neuromuscular Rehabilitation
J. Funct. Biomater. 2015, 6(2), 328-344; doi:10.3390/jfb6020328
Received: 31 March 2015 / Revised: 15 May 2015 / Accepted: 18 May 2015 / Published: 27 May 2015
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Abstract
Shape memory alloys (SMAs) are a very promising class of metallic materials that display interesting nonlinear properties, such as pseudoelasticity (PE), shape memory effect (SME) and damping capacity, due to high mechanical hysteresis and internal friction. Our group has applied SMA in [...] Read more.
Shape memory alloys (SMAs) are a very promising class of metallic materials that display interesting nonlinear properties, such as pseudoelasticity (PE), shape memory effect (SME) and damping capacity, due to high mechanical hysteresis and internal friction. Our group has applied SMA in the field of neuromuscular rehabilitation, designing some new devices based on the mentioned SMA properties: in particular, a new type of orthosis for spastic limb repositioning, which allows residual voluntary movement of the impaired limb and has no predetermined final target position, but follows and supports muscular elongation in a dynamic and compliant way. Considering patients in the sub-acute phase after a neurological lesion, and possibly bedridden, the paper presents a mobiliser for the ankle joint, which is designed exploiting the SME to provide passive exercise to the paretic lower limb. Two different SMA-based applications in the field of neuroscience are then presented, a guide and a limb mobiliser specially designed to be compatible with diagnostic instrumentations that impose rigid constraints in terms of electromagnetic compatibility and noise distortion. Finally, the paper discusses possible uses of these materials in the treatment of movement disorders, such as dystonia or hyperkinesia, where their dynamic characteristics can be advantageous. Full article
(This article belongs to the Special Issue Biomedical Applications of Shape Memory Alloys)
Open AccessArticle Computational Modeling to Predict Fatigue Behavior of NiTi Stents: What Do We Need?
J. Funct. Biomater. 2015, 6(2), 299-317; doi:10.3390/jfb6020299
Received: 31 March 2015 / Revised: 25 April 2015 / Accepted: 11 May 2015 / Published: 20 May 2015
Cited by 2 | PDF Full-text (2575 KB) | HTML Full-text | XML Full-text
Abstract
NiTi (nickel-titanium) stents are nowadays commonly used for the percutaneous treatment of peripheral arterial disease. However, their effectiveness is still debated in the clinical field. In fact a peculiar cyclic biomechanical environment is created before and after stent implantation, with the risk [...] Read more.
NiTi (nickel-titanium) stents are nowadays commonly used for the percutaneous treatment of peripheral arterial disease. However, their effectiveness is still debated in the clinical field. In fact a peculiar cyclic biomechanical environment is created before and after stent implantation, with the risk of device fatigue failure. An accurate study of the device fatigue behavior is of primary importance to ensure a successful stenting procedure. Regulatory authorities recognize the possibility of performing computational analyses instead of experimental tests for the assessment of medical devices. However, confidence in numerical methods is only possible after verification and validation of the models used. For the case of NiTi stents, mechanical properties are strongly dependent on the device dimensions and the whole treatments undergone during manufacturing process. Hence, special attention should be paid to the accuracy of the description of the device geometry and the material properties implementation into the numerical code, as well as to the definition of the fatigue limit. In this paper, a path for setting up an effective numerical model for NiTi stent fatigue assessment is proposed and the results of its application in a specific case study are illustrated. Full article
(This article belongs to the Special Issue Biomedical Applications of Shape Memory Alloys)
Open AccessArticle Cleaning Effectiveness of Three NiTi Rotary Instruments: A Focus on Biomaterial Properties
J. Funct. Biomater. 2015, 6(1), 66-76; doi:10.3390/jfb6010066
Received: 29 December 2014 / Revised: 26 January 2015 / Accepted: 3 February 2015 / Published: 16 February 2015
Cited by 1 | PDF Full-text (2541 KB) | HTML Full-text | XML Full-text
Abstract
Nickel-titanium (NiTi) instruments are commonly used for shaping the root canal system in endodontic practice. They are more flexible and have better cutting efficiency than conventional stainless steel files. The superelasticity of NiTi rotary files allows the clinicians to produce the desirable [...] Read more.
Nickel-titanium (NiTi) instruments are commonly used for shaping the root canal system in endodontic practice. They are more flexible and have better cutting efficiency than conventional stainless steel files. The superelasticity of NiTi rotary files allows the clinicians to produce the desirable tapered root canal form with a reduced tendency to canal transportation and instrument fracture. HyFlex CM instruments are new NiTi rotary instruments with shape memory produced by an innovative methodology (patent pending) that uses a complex heating and cooling treatment that controls the material’s memory. The aim of the present study was to compare the cleaning efficacy of two conventional (Mtwo, Revo-S) Ni-Ti rotary instruments with HyFlex CM. 30 single-rooted freshly extracted teeth were divided into three groups. Root canals were shaped with three NiTi instruments (Mtwo, Revo-S and HyFlex CM) using 5.25% NaOCl and 17% EDTA solutions. Specimens were fractured longitudinally and prepared for SEM analysis at standard magnification of 1000×. The presence/absence of debris smear layer and the presence/absence of smear layer at coronal, middle, and apical third of each canal were evaluated using a 5-step scale for scores. Numeric data were analyzed using Kruskall-Wallis and Mann-Whitney U statistical tests and significance was predetermined at P < 0.05. This study revealed significant differences among the various groups. Despite some minor differences, all instruments removed smear layer and debris produced during instrumentation. HyFlex CM seem to be not so effective in promoting cleanliness of root canal walls and in removing smear layer from dentine if compared to Mtwo and Revo-S. Full article
(This article belongs to the Special Issue Biomedical Applications of Shape Memory Alloys)

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