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Publications (10 of 32) Show all publications
Mehraeen, S., Asadi, M., Martinez, J. G., Persson, N.-K., Stålhand, J. & Jager, E. (2023). Yarn actuators powered by electroactive polymers for wearables. In: : . Paper presented at EuroEAP 2023,11th international conference on soft transducers and electromechanically active polymers.
Open this publication in new window or tab >>Yarn actuators powered by electroactive polymers for wearables
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2023 (English)Conference paper, Poster (with or without abstract) (Other academic)
National Category
Textile, Rubber and Polymeric Materials
Identifiers
urn:nbn:se:liu:diva-200617 (URN)
Conference
EuroEAP 2023,11th international conference on soft transducers and electromechanically active polymers
Available from: 2024-02-01 Created: 2024-02-01 Last updated: 2024-02-16
Karlsson, J., Stålhand, J., Carlhäll, C.-J., Länne, T. & Engvall, J. (2022). Abdominal Aortic Wall Cross-coupled Stiffness Could Potentially Contribute to Aortic Length Remodeling. Artery Research, 28, 113-127
Open this publication in new window or tab >>Abdominal Aortic Wall Cross-coupled Stiffness Could Potentially Contribute to Aortic Length Remodeling
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2022 (English)In: Artery Research, ISSN 1872-9312, Vol. 28, p. 113-127Article in journal (Refereed) Published
Abstract [en]

Background: Wall stiffness of the abdominal aorta is an important factor in the cardiovascular risk assessment. We investigated abdominal aortic wall stiffness divided in direct and cross‑coupled stiffness components with respect to sex and age.Methods: Thirty healthy adult males (n = 15) and females were recruited and divided into three age groups: young, middle aged and elderly. Pulsatile diameter changes were determined noninvasively by an echo‑tracking system, and intra‑aortic pressure was measured simultaneously. A mechanical model was used to compute stress and stiffness in circumferential and longitudinal directions.Results: Circumferential stretch had a higher impact on longitudinal wall stress than longitudinal stretch had on circumferential wall stress. Furthermore, there were an age‑related and sex‑independent increase in circumferential and longitudinal direct and cross‑coupled stiffnesses and a decrease in circumferential and longitudinal stretch of the abdominal aortic wall. For the young group, females had a stiffer wall compared to males, while the male aortic wall grew stiffer with age at a higher rate, reaching a similar level to that of the females in the elderly group.Conclusion: Temporal changes in aortic stiffness suggest an age‑related change in wall constituents that is expressed in terms of circumferential remodeling impacting longitudinal stress. These mechanisms may be active in the development of aortic tortuosity. We observed an age‑dependent increase in circumferential and longitudinal stiffnesses as well as decrease in stretch. A possible mechanism related to the observed changes could act via chemi‑cal alterations of wall constituents and changes in the physical distribution of fibers. Furthermore, modeling of force distribution in the wall of the human abdominal aorta may contribute to a better understanding of elastin–collagen interactions during remodeling of the aortic wall.

Place, publisher, year, edition, pages
BioMed Central (BMC), 2022
Keywords
Abdominal aorta, cardiovascular disease, wall stress, cross-coupled stiffness, sex, age, remodeling
National Category
Clinical Medicine
Identifiers
urn:nbn:se:liu:diva-190181 (URN)10.1007/s44200-022-00022-0 (DOI)000888711800001 ()
Funder
Swedish Research Council, 12661Swedish Heart Lung FoundationLinköpings universitetSwedish Research Council, 12661
Note

Funding: Linkoping University; Region Ostergotland; Medical Faculty Linkoping University; Swedish Research Council [12661]; Swedish Heart-Lung Foundation

Available from: 2022-11-28 Created: 2022-11-28 Last updated: 2024-02-23Bibliographically approved
Gade, J.-L., Stålhand, J. & Thore, C.-J. (2019). An in vivo parameter identification method for arteries: numerical validation for the human abdominal aorta. Computer Methods in Biomechanics and Biomedical Engineering, 426-441
Open this publication in new window or tab >>An in vivo parameter identification method for arteries: numerical validation for the human abdominal aorta
2019 (English)In: Computer Methods in Biomechanics and Biomedical Engineering, ISSN 1025-5842, E-ISSN 1476-8259, p. 426-441Article in journal (Refereed) Published
Abstract [en]

A method for identifying mechanical properties of arterial tissue in vivo is proposed in this paper and it is numerically validated for the human abdominal aorta. Supplied with pressure-radius data, the method determines six parameters representing relevant mechanical properties of an artery. In order to validate the method, 22 finite element arteries are created using published data for the human abdominal aorta. With these in silico abdominal aortas, which serve as mock experiments with exactly known material properties and boundary conditions, pressure-radius data sets are generated and the mechanical properties are identified using the proposed parameter identification method. By comparing the identified and pre-defined parameters, the method is quantitatively validated. For healthy abdominal aortas, the parameters show good agreement for the material constant associated with elastin and the radius of the stress-free state over a large range of values. Slightly larger discrepancies occur for the material constants associated with collagen, and the largest relative difference is obtained for the in situ axial prestretch. For pathological abdominal aortas incorrect parameters are identified, but the identification method reveals the presence of diseased aortas. The numerical validation indicates that the proposed parameter identification method is able to identify adequate parameters for healthy abdominal aortas and reveals pathological aortas from in vivo-like data.

Place, publisher, year, edition, pages
Taylor & Francis, 2019
Keywords
In vivo, parameter identification, abdominal aorta, in silico, finite element method, validation
National Category
Other Engineering and Technologies not elsewhere specified
Identifiers
urn:nbn:se:liu:diva-155056 (URN)10.1080/10255842.2018.1561878 (DOI)000466370800009 ()30806081 (PubMedID)2-s2.0-85062322494 (Scopus ID)
Funder
Swedish Research Council, 21-2014-4165
Available from: 2019-03-11 Created: 2019-03-11 Last updated: 2021-01-05Bibliographically approved
Sharifimajd, B., Ölvander, J. & Stålhand, J. (2017). Identification of the mechanical parameters for the human uterus in vivo using intrauterine pressure measurements. International Journal for Numerical Methods in Biomedical Engineering, 33(1), 1-11
Open this publication in new window or tab >>Identification of the mechanical parameters for the human uterus in vivo using intrauterine pressure measurements
2017 (English)In: International Journal for Numerical Methods in Biomedical Engineering, ISSN 2040-7939, E-ISSN 2040-7947, Vol. 33, no 1, p. 1-11Article in journal (Refereed) Published
Abstract [en]

There are limited experimental data to characterize the mechanical response of human myometrium. A method is presented in this work to identify mechanical parameters describing the active response of human myometrium from the in vivo intrauterine pressure measurements. A finite element model is developed to compute the intrauterine pressure during labor in response to an increase in the intracellular calcium ion concentration within myometrial smooth muscle cells. The finite element model provides the opportunity to tune mechanical parameters in order to fit the computed intrauterine pressure to in vivo measurements. Since the model is computationally expensive, a cheaper meta-model is generated to approximate the model response. By fitting the meta-model response to the in vivo measurements, the parameters used to determine the active response of human myometrial smooth muscle are identified.

Place, publisher, year, edition, pages
John Wiley & Sons, 2017
Keywords
human uterine smooth muscle mechanics, intrauterine pressure, parameter identification, response surface methodology
National Category
Applied Mechanics Mechanical Engineering
Identifiers
urn:nbn:se:liu:diva-121014 (URN)10.1002/cnm.2778 (DOI)000393964900001 ()26915913 (PubMedID)2-s2.0-84962638845 (Scopus ID)
Note

At the time of the thesis presentation this publication was in status Manuscript.

Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2018-01-03Bibliographically approved
Persson, N.-K., Maziz, A., Öberg, I., Christiansson, I., Stålhand, J. & Jager, E. (2017). Next generation Smart Textiles - morphing and actuating devices. In: : . Paper presented at E-MRS Spring Meeting and Exhibit, Strasbourg, France, May 22-26, 2017.
Open this publication in new window or tab >>Next generation Smart Textiles - morphing and actuating devices
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2017 (English)Conference paper, Oral presentation only (Refereed)
National Category
Textile, Rubber and Polymeric Materials
Identifiers
urn:nbn:se:liu:diva-137906 (URN)
Conference
E-MRS Spring Meeting and Exhibit, Strasbourg, France, May 22-26, 2017
Available from: 2017-06-01 Created: 2017-06-01 Last updated: 2018-01-03Bibliographically approved
Martinez, J. G., Stålhand, J., Persson, N.-K. & Jager, E. (2017). Textile actuators for wearable devices. In: : . Paper presented at 9th World Congress on Biomimetics, Artificial Muscles and Nano-Bio (BAMN2017).
Open this publication in new window or tab >>Textile actuators for wearable devices
2017 (English)Conference paper, Oral presentation only (Other academic)
National Category
Textile, Rubber and Polymeric Materials
Identifiers
urn:nbn:se:liu:diva-151747 (URN)
Conference
9th World Congress on Biomimetics, Artificial Muscles and Nano-Bio (BAMN2017)
Available from: 2018-10-04 Created: 2018-10-04 Last updated: 2018-10-12
Stålhand, J. & Holzapfel, G. A. (2016). Length adaptation of smooth muscle contractile filaments in response to sustained activation. Journal of Theoretical Biology, 397, 13-21
Open this publication in new window or tab >>Length adaptation of smooth muscle contractile filaments in response to sustained activation
2016 (English)In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 397, p. 13-21Article in journal (Refereed) Published
Abstract [en]

Airway and bladder smooth muscles are known to undergo length adaptation under sustained contraction. This adaptation process entails a remodelling of the intracellular actin and myosin filaments which shifts the peak of the active force-length curve towards the current length. Smooth muscles are therefore able to generate the maximum force over a wide range of lengths. In contrast, length adaptation of vascular smooth muscle has attracted very little attention and only a handful of studies have been reported. Although their results are conflicting on the existence of a length adaptation process in vascular smooth muscle, it seems that, at least, peripheral arteries and arterioles undergo such adaptation. This is of interest since peripheral vessels are responsible for pressure regulation, and a length adaptation will affect the function of the cardiovascular system. It has, e.g., been suggested that the inward remodelling of resistance vessels associated with hypertension disorders may be related to smooth muscle adaptation. In this study we develop a continuum mechanical model for vascular smooth muscle length adaptation by assuming that the muscle cells remodel the actomyosin network such that the peak of the active stress-stretch curve is shifted towards the operating point. The model is specialised to hamster cheek pouch arterioles and the simulated response to stepwise length changes under contraction. The results show that the model is able to recover the salient features of length adaptation reported in the literature.

Place, publisher, year, edition, pages
ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2016
Keywords
Continuum mechanics; Artery; Smooth muscle cell; Model; Remodelling
National Category
Biological Sciences
Identifiers
urn:nbn:se:liu:diva-128721 (URN)10.1016/j.jtbi.2016.02.028 (DOI)000375168300002 ()26925813 (PubMedID)
Note

Funding Agencies|Swedish Research Council [621-2009-3099]

Available from: 2016-06-01 Created: 2016-05-30 Last updated: 2018-01-03
Stålhand, J., McMeeking, R. M. & Holzapfel, G. A. (2016). On the Thermodynamics of Smooth Muscle Contraction. Journal of the mechanics and physics of solids, 94, 490-503
Open this publication in new window or tab >>On the Thermodynamics of Smooth Muscle Contraction
2016 (English)In: Journal of the mechanics and physics of solids, ISSN 0022-5096, E-ISSN 1873-4782, Vol. 94, p. 490-503Article in journal (Refereed) Published
Abstract [en]

Cell function is based on many dynamically complex networks of interacting biochemical reactions. Enzymes may increase the rate of only those reactions that are thermodynamically consistent. In this paper we specifically treat the contraction of smooth muscle cells from the continuum thermodynamics point of view by considering them as an open system where matter passes through the cell membrane. We systematically set up a well-known four-state kinetic model for the cross-bridge interaction of actin and myosin in smooth muscle, where the transition between each state is driven by forward and reverse reactions. Chemical, mechanical and energy balance laws are provided in local forms, while energy balance is also formulated in the more convenient temperature form. We derive the local (non-negative) production of entropy from which we deduce the reduced entropy inequality and the constitutive equations for the first Piola-Kirchhoff stress tensor, the heat flux, the ion and molecular flux and the entropy. One example for smooth muscle contraction is analyzed in more detail in order to provide orientation within the established general thermodynamic framework. In particular the stress evolution, heat generation, muscle shorting rate and a condition for muscle cooling is derived.

Place, publisher, year, edition, pages
Pergamon Press, 2016
Keywords
Continuum thermodynamics; smooth muscle cell; contraction; kinetic model; constitutive equation; entropy inequality; Gibbs free energy
National Category
Applied Mechanics
Identifiers
urn:nbn:se:liu:diva-129701 (URN)10.1016/j.jmps.2016.05.018 (DOI)000382342300027 ()
Available from: 2016-06-23 Created: 2016-06-23 Last updated: 2018-01-03
Sharifimajd, B., Thore, C.-J. & Stålhand, J. (2016). Simulating uterine contraction by using an electro-chemo-mechanical model. Biomechanics and Modeling in Mechanobiology, 15(3), 497-510
Open this publication in new window or tab >>Simulating uterine contraction by using an electro-chemo-mechanical model
2016 (English)In: Biomechanics and Modeling in Mechanobiology, ISSN 1617-7959, E-ISSN 1617-7940, Vol. 15, no 3, p. 497-510Article in journal (Refereed) Published
Abstract [en]

Contractions of uterine smooth muscle cells consist of a chain of physiological processes. These contractions provide the required force to expel the fetus from the uterus. The inclusion of these physiological processes is, therefore, imperative when studying uterine contractions. In this study, an electro-chemo-mechanical model to replicate the excitation, activation, and contraction of uterine smooth muscle cells is developed. The presented modeling strategy enables efficient integration of knowledge about physiological processes at the cellular level to the organ level. The model is implemented in a three-dimensional finite element setting to simulate uterus contraction during labor in response to electrical discharges generated by pacemaker cells and propagated within the myometrium via gap junctions. Important clinical factors, such as uterine electrical activity and intrauterine pressure, are predicted using this simulation. The predictions are in agreement with clinically measured data reported in the literature. A parameter study is also carried out to investigate the impact of physiologically related parameters on the uterine contractility.

Place, publisher, year, edition, pages
Springer, 2016
Keywords
Excitation-contraction model of uterine smooth muscle; Uterus contraction; Intrauterine pressure; Uterine electrical activity
National Category
Applied Mechanics
Identifiers
urn:nbn:se:liu:diva-121013 (URN)10.1007/s10237-015-0703-z (DOI)000376014800002 ()26162461 (PubMedID)
Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2018-01-03Bibliographically approved
Berglund, M., Andersson, T., Hedbrant, J., Pavlasevic, V. & Stålhand, J. (2015). Understanding the user beyond ‘common sense’ – teaching Product Ergonomics to design engineering students. In: Proceedings 19th Triennial Congress of the IEA: . Paper presented at 19th Triennial Congress of the IEA, Melbourne 9-14 August 2015. International Ergonomics Association
Open this publication in new window or tab >>Understanding the user beyond ‘common sense’ – teaching Product Ergonomics to design engineering students
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2015 (English)In: Proceedings 19th Triennial Congress of the IEA, International Ergonomics Association , 2015Conference paper, Published paper (Refereed)
Abstract [en]

Multidisciplinary frameworks are needed to develop products that fit the human. Ergonomics is a multifaceted field that encompasses physical, cognitive and organizational aspects, and it is therefore a suitable subject to be taught to design engineering students.

The objective of this paper was to describe and reflect upon how a systems perspective on Ergonomics is developed and conveyed in a course in Product Ergonomics to engineering students at the Design and Product Development (DPD) programme at Linköping University, Sweden. The paper is based on the authors’ experiences from teaching the course in Product Ergonomicsas well ason 52 students’ written reflections about their view on Ergonomics before and after taking the course.

Means and ideas for teaching Ergonomics with a systems perspective included organizing a theoretical introduction into weekly themes and thereafter integrating and applying these themes in a product concept project under supervision of a multidisciplinary teacher team.

The paper also reflects on how the systems perspective of Ergonomics is planned for and realized in the intended, implemented and attained curriculum.

Abstract [en]

Practitioner Summary: Ergonomics is a multidisciplinary field which is suitable for product development but also may be difficult to grasp. This paper describes and reflects upon how Ergonomics was taught to facilitate the development of a systems view on Ergonomics for engineering students at Linköping University, Sweden.

Means for achieving this were to: organize the course in weekly themes in which different knowledge areas within Ergonomics were elaborated, integrate these knowledge areas in a product concept project, and have a multidisciplinary teacher team.

Place, publisher, year, edition, pages
International Ergonomics Association, 2015
Keywords
systems perspective, university education, product design
National Category
Production Engineering, Human Work Science and Ergonomics
Identifiers
urn:nbn:se:liu:diva-123858 (URN)
Conference
19th Triennial Congress of the IEA, Melbourne 9-14 August 2015
Available from: 2016-01-11 Created: 2016-01-11 Last updated: 2018-01-03Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-9891-6783

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