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Gallagher S, Josyula K, Rahul, Kruger U, Gong A, Song A, Eschelbach E, Crawford D, Pham T, Sweet R, Parsey C, Norfleet J, De S. Mechanical behavior of full-thickness burn human skin is rate-independent. Sci Rep 2024; 14:11096. [PMID: 38750077 PMCID: PMC11096406 DOI: 10.1038/s41598-024-61556-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 05/07/2024] [Indexed: 05/18/2024] Open
Abstract
Skin tissue is recognized to exhibit rate-dependent mechanical behavior under various loading conditions. Here, we report that the full-thickness burn human skin exhibits rate-independent behavior under uniaxial tensile loading conditions. Mechanical properties, namely, ultimate tensile stress, ultimate tensile strain, and toughness, and parameters of Veronda-Westmann hyperelastic material law were assessed via uniaxial tensile tests. Univariate hypothesis testing yielded no significant difference (p > 0.01) in the distributions of these properties for skin samples loaded at three different rates of 0.3 mm/s, 2 mm/s, and 8 mm/s. Multivariate multiclass classification, employing a logistic regression model, failed to effectively discriminate samples loaded at the aforementioned rates, with a classification accuracy of only 40%. The median values for ultimate tensile stress, ultimate tensile strain, and toughness are computed as 1.73 MPa, 1.69, and 1.38 MPa, respectively. The findings of this study hold considerable significance for the refinement of burn care training protocols and treatment planning, shedding new light on the unique, rate-independent behavior of burn skin.
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Grants
- W911NF-17-2-0022 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
- W911NF-17-2-0022 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
- W911NF-17-2-0022 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
- W911NF-17-2-0022 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
- W912CG-20-2-0004 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
- W912CG-20-2-0004 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
- W912CG-20-2-0004 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
- W912CG-20-2-0004 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
- W912CG-20-2-0004 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
- W912CG-20-2-0004 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
- W911NF-17-2-0022 U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC
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Affiliation(s)
- Samara Gallagher
- Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA
- Center for Modeling, Simulation, and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, NY, USA
| | - Kartik Josyula
- Center for Modeling, Simulation, and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, NY, USA
| | - Rahul
- Center for Modeling, Simulation, and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, NY, USA.
| | - Uwe Kruger
- Center for Modeling, Simulation, and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, NY, USA
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA
| | - Alex Gong
- Center for Research in Education and Simulation Technologies, University of Washington, Seattle, WA, USA
| | - Agnes Song
- Center for Research in Education and Simulation Technologies, University of Washington, Seattle, WA, USA
| | - Emily Eschelbach
- UW Medicine Regional Burn Center at Harborview Medical Center, University of Washington, Seattle, WA, USA
| | - David Crawford
- UW Medicine Regional Burn Center at Harborview Medical Center, University of Washington, Seattle, WA, USA
| | - Tam Pham
- UW Medicine Regional Burn Center at Harborview Medical Center, University of Washington, Seattle, WA, USA
| | - Robert Sweet
- Center for Research in Education and Simulation Technologies, University of Washington, Seattle, WA, USA
| | - Conner Parsey
- U.S. Army Combat Capabilities Development Command - Soldier Center, Simulation and Training Technology Center, Orlando, FL, USA
| | - Jack Norfleet
- U.S. Army Combat Capabilities Development Command - Soldier Center, Simulation and Training Technology Center, Orlando, FL, USA
| | - Suvranu De
- Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA
- Center for Modeling, Simulation, and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, NY, USA
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA
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Lin CY, Sugerman GP, Kakaletsis S, Meador WD, Buganza AT, Rausch MK. Sex- and age-dependent skin mechanics-A detailed look in mice. Acta Biomater 2024; 175:106-113. [PMID: 38042263 DOI: 10.1016/j.actbio.2023.11.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 10/28/2023] [Accepted: 11/21/2023] [Indexed: 12/04/2023]
Abstract
Skin aging is of immense societal and, thus, scientific interest. Because mechanics play a critical role in skin's function, a plethora of studies have investigated age-induced changes in skin mechanics. Nonetheless, much remains to be learned about the mechanics of aging skin. This is especially true when considering sex as a biological variable. In our work, we set out to answer some of these questions using mice as a model system. Specifically, we combined mechanical testing, histology, collagen assays, and two-photon microscopy to identify age- and sex-dependent changes in skin mechanics and to relate them to structural, microstructural, and compositional factors. Our work revealed that skin stiffness, thickness, and collagen content all decreased with age and were sex dependent. Interestingly, sex differences in stiffness were age induced. We hope our findings not only further our fundamental understanding of skin aging but also highlight both age and sex as important variables when conducting studies on skin mechanics. STATEMENT OF SIGNIFICANCE: Our work addresses the question, "How do sex and age affect the mechanics of skin?" Answering this question is of both scientific and societal importance. We do so in mice as a model system. Thereby, we hope to add clarity to a body of literature that appears divided on the effect of both factors. Our findings have important implications for those studying age and sex differences, especially in mice as a model system.
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Affiliation(s)
- Chien-Yu Lin
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Gabriella P Sugerman
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Sotirios Kakaletsis
- Department of Aerospace Engineering & Engineering Mechanics, The University of Texas at Austin, Austin, TX, USA
| | - William D Meador
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Adrian T Buganza
- Department of Mechanical Engineering, Purdue University, West Lafayette, IN, USA
| | - Manuel K Rausch
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA; Department of Aerospace Engineering & Engineering Mechanics, The University of Texas at Austin, Austin, TX, USA; Oden Institute for Computational Engineering & Sciences, The University of Texas at Austin, Austin, TX, USA.
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3
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Lin CY, Sugerman GP, Kakaletsis S, Meador WD, Buganza AT, Rausch MK. Sex- and Age-dependent Skin Mechanics - A Detailed Look in Mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.08.531781. [PMID: 36945509 PMCID: PMC10028869 DOI: 10.1101/2023.03.08.531781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
Skin aging is of immense societal and, thus, scientific interest. Because mechanics play a critical role in skin's function, a plethora of studies have investigated age-induced changes in skin mechanics. Nonetheless, much remains to be learned about the mechanics of aging skin. This is especially true when considering sex as a biological variable. In our work, we set out to answer some of these questions using mice as a model system. Specifically, we combined mechanical testing, histology, collagen assays, and two-photon microscopy to identify age- and sex-dependent changes in skin mechanics and to relate them to structural, microstructural, and compositional factors. Our work revealed that skin stiffness, thickness, and collagen content all decreased with age and were sex dependent. Interestingly, sex differences in stiffness were age induced. We hope our findings not only further our fundamental understanding of skin aging but also highlight both age and sex as important variables when conducting studies on skin mechanics.
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Affiliation(s)
- Chien-Yu Lin
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas, USA
| | - Gabriella P Sugerman
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas, USA
| | - Sotirios Kakaletsis
- Department of Aerospace Engineering & Engineering Mechanics, The University of Texas at Austin, Austin, Texas, USA
| | - William D Meador
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas, USA
| | - Adrian T Buganza
- Department of Mechanical Engineering, Purdue University, West Lafayette, Indiana, USA
| | - Manuel K Rausch
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas, USA
- Department of Aerospace Engineering & Engineering Mechanics, The University of Texas at Austin, Austin, Texas, USA
- Oden Institute for Computational Engineering & Sciences, The University of Texas at Austin, Austin, Texas, USA
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Toaquiza Tubon JD, Moreno-Flores O, Sree VD, Tepole AB. Anisotropic damage model for collagenous tissues and its application to model fracture and needle insertion mechanics. Biomech Model Mechanobiol 2022; 21:1-16. [PMID: 36057750 DOI: 10.1007/s10237-022-01624-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 08/02/2022] [Indexed: 11/30/2022]
Abstract
The analysis of tissue mechanics in biomedical applications demands nonlinear constitutive models able to capture the energy dissipation mechanisms, such as damage, that occur during tissue deformation. Furthermore, implementation of sophisticated material models in finite element models is essential to improve medical devices and diagnostic tools. Building on previous work toward microstructure-driven models of collagenous tissue, here we show a constitutive model based on fiber orientation and waviness distributions for skin that captures not only the anisotropic strain-stiffening response of this and other collagen-based tissues, but, additionally, accounts for tissue damage directly as a function of changes in the microstructure, in particular changes in the fiber waviness distribution. The implementation of this nonlinear constitutive model as a user subroutine in the popular finite element package Abaqus enables large-scale finite element simulations for biomedical applications. We showcase the performance of the model in fracture simulations during pure shear tests, as well as simulations of needle insertion into skin relevant to auto-injector design.
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Affiliation(s)
| | - Omar Moreno-Flores
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, USA
| | - Vivek D Sree
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, USA
| | - Adrian B Tepole
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, USA. .,Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA.
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