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Rodriguez AJ, Vasudevan S, Farahmand M, Weininger S, Vogt WC, Scully CG, Ramella-Roman J, Pfefer TJ. Tissue mimicking materials and finger phantom design for pulse oximetry. BIOMEDICAL OPTICS EXPRESS 2024; 15:2308-2327. [PMID: 38633081 PMCID: PMC11019708 DOI: 10.1364/boe.518967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 03/03/2024] [Accepted: 03/03/2024] [Indexed: 04/19/2024]
Abstract
Pulse oximetry represents a ubiquitous clinical application of optics in modern medicine. Recent studies have raised concerns regarding the potential impact of confounders, such as variable skin pigmentation and perfusion, on blood oxygen saturation measurement accuracy in pulse oximeters. Tissue-mimicking phantom testing offers a low-cost, well-controlled solution for characterizing device performance and studying potential error sources, which may thus reduce the need for costly in vivo trials. The purpose of this study was to develop realistic phantom-based test methods for pulse oximetry. Material optical and mechanical properties were reviewed, selected, and tuned for optimal biological relevance, e.g., oxygenated tissue absorption and scattering, strength, elasticity, hardness, and other parameters representing the human finger's geometry and composition, such as blood vessel size and distribution, and perfusion. Relevant anatomical and physiological properties are summarized and implemented toward the creation of a preliminary finger phantom. To create a preliminary finger phantom, we synthesized a high-compliance silicone matrix with scatterers for embedding flexible tubing and investigated the addition of these scatterers to novel 3D printing resins for optical property control without altering mechanical stability, streamlining the production of phantoms with biologically relevant characteristics. Phantom utility was demonstrated by applying dynamic, pressure waveforms to produce tube volume change and resultant photoplethysmography (PPG) signals. 3D printed phantoms achieved more biologically relevant conditions compared to molded phantoms. These preliminary results indicate that the phantoms show strong potential to be developed into tools for evaluating pulse oximetry performance. Gaps, recommendations, and strategies are presented for continued phantom development.
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Affiliation(s)
- Andres J. Rodriguez
- Department of Biomedical Engineering, Florida International University, Miami. Florida, 33174, USA
| | - Sandhya Vasudevan
- Division of Biomedical Physics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Masoud Farahmand
- Division of Biomedical Physics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Sandy Weininger
- Division of Biomedical Physics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD 20993, USA
| | - William C. Vogt
- Division of Biomedical Physics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Christopher G. Scully
- Division of Biomedical Physics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Jessica Ramella-Roman
- Department of Biomedical Engineering, Florida International University, Miami. Florida, 33174, USA
| | - T. Joshua Pfefer
- Division of Biomedical Physics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD 20993, USA
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Chaufer M, Delille R, Bourel B, Maréchal C, Lauro F, Mauzac O, Roth S. Review of non-penetrating ballistic testing techniques for protection assessment: From biological data to numerical and physical surrogates. Proc Inst Mech Eng H 2024; 238:383-402. [PMID: 38415326 DOI: 10.1177/09544119241232122] [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] [Indexed: 02/29/2024]
Abstract
Human surrogates have long been employed to simulate human behaviour, beginning in the automotive industry and now widely used throughout the safety framework to estimate human injury during and after accidents and impacts. In the specific context of blunt ballistics, various methods have been developed to investigate wound injuries, including tissue simulants such as clays or gelatine ballistic, physical dummies and numerical models. However, all of these surrogate entities must be biofidelic, meaning they must accurately represent the biological properties of the human body. This paper provides an overview of physical and numerical surrogates developed specifically for blunt ballistic impacts, including their properties, use and applications. The focus is on their ability to accurately represent the human body in the context of blunt ballistic impact.
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Affiliation(s)
- Martin Chaufer
- Interdisciplinary Laboratory Carnot of Bourgogne-Site UTBM, UMR 6303, CNRS/Université Bourgogne Franche-Comté (UBFC), Belfort, France
| | - Rémi Delille
- Univ. Polytechnique Hauts-de-France, CNRS, UMR 8201, LAMIH, Laboratoire d'Automatique de Mécanique et d'Informatique Industrielles et Humaines, Valenciennes, France
| | - Benjamin Bourel
- Univ. Polytechnique Hauts-de-France, CNRS, UMR 8201, LAMIH, Laboratoire d'Automatique de Mécanique et d'Informatique Industrielles et Humaines, Valenciennes, France
| | - Christophe Maréchal
- Univ. Polytechnique Hauts-de-France, CNRS, UMR 8201, LAMIH, Laboratoire d'Automatique de Mécanique et d'Informatique Industrielles et Humaines, Valenciennes, France
| | - Franck Lauro
- Univ. Polytechnique Hauts-de-France, CNRS, UMR 8201, LAMIH, Laboratoire d'Automatique de Mécanique et d'Informatique Industrielles et Humaines, Valenciennes, France
- Insa Hauts-de-France, Valenciennes, France
| | - Olivier Mauzac
- French Ministry of Interior, CREL/DEPAFI, Place Beauvau, Paris, France
| | - Sébastien Roth
- Interdisciplinary Laboratory Carnot of Bourgogne-Site UTBM, UMR 6303, CNRS/Université Bourgogne Franche-Comté (UBFC), Belfort, France
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Crossland SR, Sairally F, Edwards J, Culmer P, Brockett CL. Mechanical characteristics of diabetic and non-diabetic plantar skin. J Mech Behav Biomed Mater 2024; 150:106279. [PMID: 38007990 DOI: 10.1016/j.jmbbm.2023.106279] [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: 05/19/2023] [Revised: 06/28/2023] [Accepted: 11/23/2023] [Indexed: 11/28/2023]
Abstract
Diabetic foot ulceration is linked to high amputation and mortality rates, with the substantial associated annual spend on the at-risk diabetic foot reflecting the intensive time and labour involved in treatment. Assessing plantar interactions and developing improved understanding of the formation pathways of diabetic ulceration is important to orthotic interventions and patient outcomes. Plantar skin surrogates which emulate the mechanical and tribological characteristics can help improve physical models of ulceration, reduce reliance on cadaveric use and inform more complex computational modelling approaches. The information available from existing studies to characterise plantar skin is limited, typically featuring ex-vivo representations of skin and subcutaneous tissue combined and given focus to shear studies with time dependency. The aim of this study is to improve understanding of plantar tissue mechanics by assessing the mechanical characteristics of plantar skin in two groups; (1) non-diabetic and (2) diabetic donors without the subcutaneous tissue attachment of previous work in this field. Digital image correlation was used to assess inherent skin pre-tension of the plantar rearfoot prior to dissection. Young's modulus, storage and loss moduli were tested for using tensile stress-strain failure analysis and tensile and compressive dynamic mechanical analysis, which was conducted on excised plantar rearfoot donor specimens for both disease state cohorts at frequencies reflecting those achieved in activities of daily living. Plantar skin thickness for donor specimens were comparable to values obtained using ultrasound acquired in vivo values. Median tensile storage and loss moduli, along with Young's modulus, was higher in the diabetic cohort. With a mean Young's modulus of 0.83 ± 0.49 MPa and 1.33 ± 0.43 MPa for non-diabetic and diabetic specimens respectively. Compressive studies showed consistency between cohorts for median storage and loss moduli. The outcomes from this study show mechanical characteristics of plantar skin without the involvement of subcuteanous tissues under reflective daily achieved loading regimes, showing differences in the non-diabetic and diabetic specimens trialled to support improved understanding of plantar tissue response under tribological interactions.
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Affiliation(s)
- Sarah R Crossland
- Department of Mechanical Engineering, University of Leeds, Leeds, UK.
| | | | - Jen Edwards
- Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Peter Culmer
- Department of Mechanical Engineering, University of Leeds, Leeds, UK
| | - Claire L Brockett
- Insigneo Institute for in silico Medicine, University of Sheffield, Sheffield, UK
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Frankfort MGH, Lauwers I, Pruijn EMC, Dijkstra SF, Boormans LHG, Schouten NA, van Donkelaar CC, Janssens HM. Minimizing Aerosol Leakage from Facemasks in the COVID-19 Pandemic. J Aerosol Med Pulm Drug Deliv 2023. [PMID: 37172274 DOI: 10.1089/jamp.2022.0036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023] Open
Abstract
Background: Aerosol therapies with vented facemasks are considered a risk for nosocomial transmission of viruses such as severe acute respiratory syndrome coronavirus 2. The transmission risk can be decreased by minimizing aerosol leakage and filtering the exhaled air. Objective: In this study, we determined which closed facemask designs show the least leakage. Methods: Smoke leakage was quantified during in- and exhalation in a closed system with expiration filter for three infant, six child, and six adult facemasks (three times each mask), using age-appropriate anatomical face models and breathing patterns. To assess leakage, smoke release was recorded and cumulative average pixel intensity (cAPI) was calculated. Results: In the adult group, aircushion edges resulted in less leakage than soft edges (cAPI: 407 ± 250 vs. 774 ± 152) (p = 0.004). The Intersurgical® Economy 5 mask (cAPI: 146 ± 87) also released less smoke than the Intersurgical® Clearlite 5 (cAPI: 748 ± 68) mask with the same size, but different geometry and edge type (p-value <0.05). Moreover, mask size had an effect, as there was a difference between Intersurgical® Economy 4 (cAPI: 708 ± 346) and 5, which have the same geometry but a different size (p-value <0.05). Finally, repositioning masks increased the standard deviations. Mask leakage was not dependent on breathing patterns within the child group. Conclusions: Mask leakage can be minimized by using a closed system with a well-fitting mask that is appropriately positioned. To decrease leakage, and therewith minimize potential viral transmission, selecting a well-fitting mask with an aircushion edge is to be recommended.
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Affiliation(s)
- Mylene G H Frankfort
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Iris Lauwers
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Emerentia M C Pruijn
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Sjoerd F Dijkstra
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Liza H G Boormans
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Nicolaas A Schouten
- TU/e Innovation Space, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Corrinus C van Donkelaar
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Hettie M Janssens
- Department of Pediatrics, Division of Respiratory Medicine and Allergology, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands
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Warnung L, Sattler S, Haiden E, Schober S, Pahr D, Reisinger A. A mechanically validated open-source silicone model for the training of gastric perforation sewing. BMC MEDICAL EDUCATION 2023; 23:261. [PMID: 37076839 PMCID: PMC10116820 DOI: 10.1186/s12909-023-04174-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 03/17/2023] [Indexed: 05/03/2023]
Abstract
BACKGROUND Gastrointestinal perforation is commonly seen in emergency departments. The perforation of the stomach is an emergency situation that requires immediate surgical treatment. The necessary surgical skills require regular practical training. Owing to patient`s safety, in vivo training opportunities in medicine are restricted. Animal tissue especially porcine tissue, is commonly used for surgical training. Due to its limiting factors, artificial training models are often to be preferred. Many artificial models are on the market but to our knowledge, none that mimic the haptic- and sewing properties of a stomach wall at the same time. In this study, an open source silicone model of a gastric perforation for training of gastric sewing was developed that attempts to provide realistic haptic- and sewing behaviour. METHODS To simulate the layered structure of the human stomach, different silicone materials were used to produce three different model layups. The production process was kept as simple as possible to make it easily reproducible. A needle penetration setup as well as a systematic haptic evaluation were developed to compare these silicone models to a real porcine stomach in order to identify the most realistic model. RESULTS A silicone model consisting of three layers was identified as being the most promising and was tested by clinical surgeons. CONCLUSIONS The presented model simulates the sewing characteristics of a human stomach wall, is easily reproducible at low-costs and can be used for practicing gastric suturing techniques. TRIAL REGISTRATIONS Not applicable.
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Affiliation(s)
- Lukas Warnung
- Department of Anatomy and Biomechanics, Division Biomechanics, Karl Landsteiner University of Health Sciences, Dr. Karl-Dorrek-Straße 30, Krems, 3500, Austria.
- Division of Radiotherapy-Radiation Oncology, University Hospital Krems, Mitterweg 10, Krems, 3500, Austria.
| | - Stefan Sattler
- Department of Surgery, University Hospital Tulln, Alter Ziegelweg 10, Tulln, 3430, Austria
- Karl Landsteiner University of Health Sciences, Dr. Karl-Dorrek-Straße 30, Krems, 3500, Austria
| | - Elmar Haiden
- Department of Surgery, University Hospital Tulln, Alter Ziegelweg 10, Tulln, 3430, Austria
- Karl Landsteiner University of Health Sciences, Dr. Karl-Dorrek-Straße 30, Krems, 3500, Austria
| | - Sophie Schober
- Medical Science and Human Medicine study programme, Karl Landsteiner University of Health Sciences, Dr. Karl-Dorrek-Straße 30, Krems, 3500, Austria
| | - Dieter Pahr
- Department of Anatomy and Biomechanics, Division Biomechanics, Karl Landsteiner University of Health Sciences, Dr. Karl-Dorrek-Straße 30, Krems, 3500, Austria
- Institute for Lightweight Design and Structural Biomechanics, University of Technology Vienna, Getreidemarkt 9, Wien, 1060, Austria
| | - Andreas Reisinger
- Department of Anatomy and Biomechanics, Division Biomechanics, Karl Landsteiner University of Health Sciences, Dr. Karl-Dorrek-Straße 30, Krems, 3500, Austria
- Institute for Lightweight Design and Structural Biomechanics, University of Technology Vienna, Getreidemarkt 9, Wien, 1060, Austria
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Singh G, Chanda A. Development and Mechanical Characterization of Artificial Surrogates for Brain Tissues. BIOMEDICAL ENGINEERING ADVANCES 2023. [DOI: 10.1016/j.bea.2023.100084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/31/2023] Open
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Surface wave analysis of the skin for penetrating and non-penetrating projectile impact in porcine legs. Forensic Sci Med Pathol 2023; 19:34-43. [PMID: 36100841 DOI: 10.1007/s12024-022-00521-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2022] [Indexed: 11/27/2022]
Abstract
Secondary blast injuries may result from high-velocity projectile fragments which ultimately increase medical costs, reduce active work time, and decrease quality of life. The role of skin penetration requires more investigation in energy absorption and surface mechanics for implementation in computational ballistic models. High-speed ballistic penetration studies have not considered penetrating and non-penetrating biomechanical properties of the skin, including radial wave displacement, resultant surface wave speed, or projectile material influence. A helium-pressurized launcher was used to accelerate 3/8″ (9.525 mm) diameter spherical projectiles toward seventeen whole porcine legs from seven pigs (39.53 ± 7.28 kg) at projectile velocities below and above V50. Projectiles included a mix of materials: stainless steel (n = 26), Si3N4 (n = 24), and acetal plastic (n = 24). Tracker video analysis software was used to determine projectile velocity at impact from the perpendicular view and motion of the tissue displacement wave from the in-line view. Average radial wave displacement and surface wave speed were calculated for each projectile material and categorized by penetrating or non-penetrating impacts. Two-sample t-tests determined that non-penetrating projectiles resulted in significantly faster surface wave speeds in porcine skin for stainless steel (p = 0.002), plastic (p = 0.004), and Si3N4 ball bearings (p = 0.014), while ANOVA determined significant differences in radial wave displacement and surface wave speed between projectile materials. Surface wave speed was used to quantify mechanical properties of the skin including elastic modulus, shear modulus, and bulk modulus during ballistic impact, which may be implemented to simulate accurate deformation behavior in computational impact models.
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Gupta V, Gupta S, Chanda A. Development of an ultra-low-cost planar biaxial tester for soft tissue characterization. Biomed Phys Eng Express 2023; 9. [PMID: 36745909 DOI: 10.1088/2057-1976/acb940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 02/06/2023] [Indexed: 02/08/2023]
Abstract
Nowadays, the research in the arena of biomedical engineering or specifically soft tissue characterization is rapidly increasing. Due to the complex properties of soft tissues such as, anisotropy and viscoelasticity, it is difficult to predict the deformation behaviour. Hence, soft tissue characterization is essential to analyze these metrics. Soft tissue characterization, specifically, can be done by implementing a planar biaxial tester. Currently, available biaxial testers are mostly developed with respect to other mechanical components such as metals, and not for the soft tissues. Also, these devices are very costly, which makes it difficult for the low and middle income countries to perform this characterization. To solve this problem, in this work, an extremely low-cost biaxial tester was designed and developed. The design of the biaxial tester was simple and modular to allow device modifications according to the applications. The device has a force capability of less than 0.4 kN and a variable speed of 18 mm min-1to 300 mm min-1. The biaxial tester was validated using a standard test material with mechanical testing machine and was further tested on several wound geometries including circular, square, diamond shaped, L-Plasty, and elliptical. The developed fully automated device exhibited high accuracy with real-time monitoring. Furthermore, test results on the wounds showed the device's capability to differentiate amongst the considered wound geometries. This device can be helpful to medical students and doctors in understanding the mechanical behaviour of soft tissues during injury induced damage, disease, wounds healing and also for plethora of applications such as expansion testing of skin grafts.
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Affiliation(s)
- Vivek Gupta
- Centre for Biomedical Engineering, Indian Institute of Technology (IIT), Delhi, India
| | - Shubham Gupta
- Centre for Biomedical Engineering, Indian Institute of Technology (IIT), Delhi, India
| | - Arnab Chanda
- Centre for Biomedical Engineering, Indian Institute of Technology (IIT), Delhi, India.,Department of Biomedical Engineering, All India Institute of Medical Sciences (AIIMS), Delhi, India
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Singh R, Singh R, Sen C, Gautam U, Roy S, Suri A. Mechanical Characterization and Standardization of Silicon Scalp and Dura Surrogates for Neurosurgical Simulation. World Neurosurg 2023; 169:e197-e205. [PMID: 36415013 DOI: 10.1016/j.wneu.2022.10.090] [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: 08/25/2022] [Accepted: 10/25/2022] [Indexed: 11/07/2022]
Abstract
BACKGROUND Simulation-based neurosurgical training allows the development of surgical skills outside the operating room. However, the use of nonstandardized materials and poor haptic feedback remain the primary limitations of the surgical simulators. Therefore, this work proposes a comprehensive scheme for scalp and dura surrogate synthesis and their standardization for neurosurgical training. METHODS Eight different variants of silicone-based scalp (S1-S8) and dura (D1-D8) surrogates were synthesized. The samples were evaluated by 26 neurosurgeons. They provided their feedback in a Likert scale questionnaire. Kruskal-Wallis test with Dunn multiple comparisons was used for statistical analysis of surgeons' scores. The samples were mechanically characterized using Shore A hardness and dynamic nanoindentation testing. RESULTS The highest mean Likert score values were obtained for S3 scalp and D8 dura variants. The comparison of S3 and D8 with the rest of the variants in the respective groups was statistically significant in 21 of 28 instances. The average Shore A hardness and storage modulus of the S3 variant were 21.9 DU and 505.3 kPa, respectively. The corresponding values for the D8 variant were 32.5 DU and 632 kPa, respectively. CONCLUSIONS This study proposes a method for the synthesis, evaluation, and standardization of scalp and dura surrogates. The study achieved standardized silicone compositions along with a recommendable range of Shore hardness and viscoelastic moduli values for the scalp and dura surrogates. This work can be extended for the standardization of surrogates for other tissues involved in neurosurgical simulators.
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Affiliation(s)
- Ramandeep Singh
- Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi, India
| | - Rajdeep Singh
- Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi, India
| | - Chander Sen
- Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi, India
| | - Umesh Gautam
- Department of Applied Mechanics, Indian Institute of Technology Delhi, New Delhi, India
| | - Sitikantha Roy
- Department of Applied Mechanics, Indian Institute of Technology Delhi, New Delhi, India
| | - Ashish Suri
- Department of Neurosurgery, All India Institute of Medical Sciences, New Delhi, India.
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Hannay V, Rahul FNU, Josyula K, Kruger U, Gallagher S, Lee S, Ye H, Makled B, Parsey C, Norfleet J, De S. Synthetic tissues lack the fidelity for the use in burn care simulators. Sci Rep 2022; 12:21398. [PMID: 36496535 PMCID: PMC9741590 DOI: 10.1038/s41598-022-25234-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 11/28/2022] [Indexed: 12/13/2022] Open
Abstract
This work compares the mechanical response of synthetic tissues used in burn care simulators from ten different manufacturers with that of ex vivo full thickness burned porcine skin as a surrogate for human skin tissues. This is of high practical importance since incorrect mechanical properties of synthetic tissues may introduce a negative bias during training due to the inaccurate haptic feedback from burn care simulator. A negative training may result in inadequately performed procedures, such as in escharotomy, which may lead to muscle necrosis endangering life and limb. Accurate haptic feedback in physical simulators is necessary to improve the practical training of non-expert providers for pre-deployment/pre-hospital burn care. With the U.S. Army's emerging doctrine of prolonged field care, non-expert providers must be trained to perform even invasive burn care surgical procedures when indicated. The comparison reported in this article is based on the ultimate tensile stress, ultimate tensile strain, and toughness that are measured at strain rates relevant to skin surgery. A multivariate analysis using logistic regression reveals significant differences in the mechanical properties of the synthetic and the porcine skin tissues. The synthetic and porcine skin tissues show a similar rate dependent behavior. The findings of this study are expected to guide the development of high-fidelity burn care simulators for the pre-deployment/pre-hospital burn care provider education.
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Affiliation(s)
- Vanessa Hannay
- grid.33647.350000 0001 2160 9198Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY USA
| | - F. N. U. Rahul
- grid.33647.350000 0001 2160 9198Center for Modeling, Simulation, and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, NY USA
| | - Kartik Josyula
- grid.33647.350000 0001 2160 9198Center for Modeling, Simulation, and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, NY USA
| | - Uwe Kruger
- grid.33647.350000 0001 2160 9198Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY USA
| | - Samara Gallagher
- grid.33647.350000 0001 2160 9198Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY USA
| | - Sangrock Lee
- grid.33647.350000 0001 2160 9198Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY USA ,grid.33647.350000 0001 2160 9198Center for Modeling, Simulation, and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, NY USA
| | - Hanglin Ye
- grid.33647.350000 0001 2160 9198Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY USA ,grid.33647.350000 0001 2160 9198Center for Modeling, Simulation, and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, NY USA
| | - Basiel Makled
- U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC, Orlando, FL USA
| | - Conner Parsey
- U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC, Orlando, FL USA
| | - Jack Norfleet
- U.S. Army Futures Command, Combat Capabilities Development Command Soldier Center STTC, Orlando, FL USA
| | - Suvranu De
- grid.33647.350000 0001 2160 9198Center for Modeling, Simulation, and Imaging in Medicine, Rensselaer Polytechnic Institute, Troy, NY USA
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Kang MS, Kwon M, Lee SH, Kim WH, Lee GW, Jo HJ, Kim B, Yang SY, Kim KS, Han DW. 3D printing of skin equivalents with hair follicle structures and epidermal-papillary-dermal layers using gelatin/hyaluronic acid hydrogels. Chem Asian J 2022; 17:e202200620. [PMID: 35866189 DOI: 10.1002/asia.202200620] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 07/18/2022] [Indexed: 11/10/2022]
Abstract
Recent advances in three-dimensional (3D) bioprinting technologies enabled the fabrication of sophisticated live 3D tissue analogs. Although various hydrogel-based bioink has been reported, the development of advanced bioink materials that can reproduce the composition of native extracellular matrix (ECM) accurately and mimic the intrinsic property of laden cells is still challenging. In this work, 3D printed skin equivalents incorporating hair follicle structures and epidermal-papillary-dermal layers are fabricated with gelatin methacryloyl (GelMA)/hyaluronic acid (HA) MA (HAMA) hydrogel (GelMA/HAMA) bioink. The composition of collagen and glycosaminoglycan (GAG) of native skin was recapitulated by adjusting the combination of GelMA and HAMA. The GelMA/HAMA bioink was proven to have excellent viscoelastic and physicochemical properties, 3D printability, cytocompatibility, and functionality to maintain the hair inductive potency and facilitated spontaneous hair pore development. Overall, we suggest that the GelMA/HAMA hydrogels can be promising candidates as bioinks for the 3D printing of skin equivalents with epidermal-papillary-dermal multi-layers and hair follicle structures, and they might serve as a useful model in skin tissue engineering and regeneration.
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Affiliation(s)
- Moon Sung Kang
- Pusan National University, Cogno-Mechatronics Engineering, KOREA, REPUBLIC OF
| | - Mina Kwon
- Pusan National University, School of Chemical Engineering, KOREA, REPUBLIC OF
| | - Seok Hyun Lee
- Pusan National University, Cogno-Mechatronics Engineering, KOREA, REPUBLIC OF
| | - Won-Hyeon Kim
- Seoul National University Dental Hospital, Dental Life Science Research Institute, KOREA, REPUBLIC OF
| | - Gyeong Won Lee
- Pusan National University - Milyang Campus, Biomaterials Science, KOREA, REPUBLIC OF
| | - Hyo Jung Jo
- Pusan National University, Cogno-Mechatronics Engineering, KOREA, REPUBLIC OF
| | - Bongju Kim
- Seoul National University Dental Hospital, Dental Life Science Research Institute, KOREA, REPUBLIC OF
| | - Seung Yun Yang
- Pusan National University - Milyang Campus, Biomaterials Science, KOREA, REPUBLIC OF
| | - Ki Su Kim
- Pusan National University, School of Chemical Engineering, KOREA, REPUBLIC OF
| | - Dong-Wook Han
- Pusan National University, Cogno-Mechatronics Engineering, Department of Cogno-Mechatronics Engineering, College of Nanoscience & Nanotechnology, Pusan National University, Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan 46241, Korea, 46241, Busan, KOREA, REPUBLIC OF
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Hankare P, Agrawala A, Menezes V. High-Speed Jet Injector for Pharmaceutical Applications. J Med Device 2022. [DOI: 10.1115/1.4054549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Abstract
A shock wave-driven needle-free syringe was developed and tested for liquid jet delivery into an artificial skin model and porcine skin samples. The device could deliver an adequate volume of liquid to a depth sufficient for drug dissemination in skin samples. The device is equipped with a splash-proof conduit and a silencer for smooth operation. The concept is expected to minimize the pain of liquid injection by a) minimally breaching the blood vessels in the skin, b) reducing trauma, inflammation and aiding regeneration of the incised spot by the liquid of the jet, and c) preserving most of the micro-circulation system in the target, enabling an effective drug uptake. A theoretical model that predicts jet penetration into viscoelastic targets is derived and presented. A sound agreement has been observed between the experimental jet penetration depths and the corresponding theoretical predictions. The development can offer a cost-effective, minimally invasive health care solution for immunization and drug delivery.
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Affiliation(s)
- Priyanka Hankare
- Indian Institute of Technology Bombay, Department of Aerospace Engineering, IIT Bombay, Powai, Mumbai - 400076, India
| | - Ashish Agrawala
- Indian Institute of Technology Bombay, Department of Aerospace Engineering, IIT Bombay, Powai, Mumbai - 400076, India
| | - Viren Menezes
- Indian Institute of Technology Bombay, Department of Aerospace Engineering, IIT Bombay, Powai, Mumbai - 400076, India
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Gupta S, Gupta V, Chanda A. Biomechanical modeling of novel high expansion auxetic skin grafts. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2022; 38:e3586. [PMID: 35266310 DOI: 10.1002/cnm.3586] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 02/24/2022] [Accepted: 03/03/2022] [Indexed: 06/14/2023]
Abstract
Over 20 million burn injuries are reported every year, with severe cases requiring skin grafting. Traditionally, split thickness skin grafts are prepared by excising a small portion of healthy skin and its incision patterning using a suitable meshing device, which allows the graft to be expanded beyond its capacity. To date, the maximum expansion achieved through skin grafting has been reported to be less than three times, which is not sufficient for covering large burn sites with limited donor site skin. In this work, we have attempted to study skin graft expansion potential with novel auxetic patterns, which are known to exhibit negative Poisson's effect. Two-layer skin graft models were developed using eight different auxetic incision patterns, and subjected to uniaxial and biaxial tensile strains. The Poisson's ratio, meshing ratio, and induced stresses were characterized for all graft models. The numerical results indicated expansion potentials greater than that of traditional skin grafts across all loads. Extremely high expansions (i.e., >30 times) were estimated for the I-Shaped Re-entrant and Rotating Triangles shaped auxetic models without rupture. Such pioneering findings are anticipated to initiate ground-breaking advances towards skin graft research and improved outcomes in burn surgeries.
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Affiliation(s)
- Shubham Gupta
- Centre for Biomedical Engineering, Indian Institute of Technology (IIT), New Delhi, India
| | - Vivek Gupta
- Centre for Biomedical Engineering, Indian Institute of Technology (IIT), New Delhi, India
| | - Arnab Chanda
- Centre for Biomedical Engineering, Indian Institute of Technology (IIT), New Delhi, India
- Department of Biomedical Engineering, All India Institute of Medical Sciences (AIIMS), New Delhi, India
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14
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Skeletal muscle surrogates for the acquisition of muscle repair skills in upper limb surgery. J Mech Behav Biomed Mater 2022; 131:105216. [PMID: 35487107 DOI: 10.1016/j.jmbbm.2022.105216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 03/31/2022] [Accepted: 04/01/2022] [Indexed: 11/23/2022]
Abstract
INTRODUCTION The required fidelity of synthetic materials in surgical simulators to teach tissue handling and repair requirements should be as accurate as possible. There is a poor understanding of the relationship between choice of muscle surrogates and training outcome for trainee surgeons. To address this, the mechanical characteristics of several candidate synthetic muscle surrogates were measured, and their subjective biofidelity was qualitatively assessed by surgeons. METHODS Silicone was selected after assessing several material options and 16 silicone-based surrogates were evaluated. Three of the closest samples to muscle (Samples 1.1, 1.2, 1.3) and one with inserted longitudinal fibres (1.2F) were mechanically tested in the following: compression and tension, needle puncture force and suture pull-out in comparison with real muscle. The four samples were evaluated by 17 Plastic and Orthopaedic surgeons to determine their views of the fidelity with regard to the handling properties, needle insertion and ease of suture pull-out. RESULTS The mechanical testing showed the surrogates exhibited varying characteristics that matched some of the properties of muscle, though none recreated all the mechanical characteristics of native muscle. Good biofidelity was generally achieved for compression stiffness and needle puncture force, but it was evident that tensile stiff was too low for all samples. The pull-out forces were variable and too low, except for the sample with longitudinal fibres. In the qualitative assessment, the overall median scores for the four surrogate samples were all between 30 and 32 (possible range 9-45), indicating limited differentiation of the samples tested by the surgeons. CONCLUSIONS The surrogate materials showed a range of mechanical properties bracketing those of real muscle, thus presenting a suitable combination of candidates for use in simulators to attain the requirements as set out in the learning outcomes of muscle repair. However, despite significant mechanical differences between the samples, all surgeons found the samples to be similar to each other.
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Ellabban MA, Elsayed MA, Zein AB, Ghorab M, Elmasry M, Masadeh S, Abo-Ella MM, Sadek AF. Virtual planning of the anterolateral thigh free flap for heel reconstruction. Microsurgery 2022; 42:460-469. [PMID: 35362110 DOI: 10.1002/micr.30886] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 01/24/2022] [Accepted: 03/24/2022] [Indexed: 11/06/2022]
Abstract
PURPOSE three dimensional (3-D) virtual planning is an example of computer assisted surgery that improved management of composite tissue defects. However, converting the 3-D construct into two dimensional format is challenging. The purpose of this study was to assess 3-D virtual planning of complex heel defects for better optimized reconstruction. PATIENTS AND METHODS a prospective analysis of 10 patients [9 male and 1 female; mean age = 27.9 years] with post-traumatic heel defects was performed. Heel defects comprised types II (three patients) or III (seven patients) according to Hidalgo and Shaw and were managed using anterolateral thigh (ALT) free flap adopting 3-D virtual planning of the actual defect which was converted into a silicone two dimensional mold. The mean definitive size of the defects was 63.4 cm3 . Functional, aesthetic, and sensory evaluations of both donor and recipient sites were performed 1 year after surgery. RESULTS Six patients received thinned ALT (mean size = 139 cm3 ) while four patients received musculofasciocutaneous ALT flap (mean size = 199 cm3 ). One flap exhibited partial skin flap necrosis. Another flap was salvaged after re-exploration secondary to venous congestion. The mean follow-up was 20.2 months. The Maryland foot score showed 4 excellent, 5 good, and 1 fair cases. The mean American Orthopedic Foot and Ankle hind foot scoring was 76.3 (range: 69-86). All patients regained their walking capability. CONCLUSIONS 3-D virtual planning of complex heel defects facilitates covering non-elliptical defects while harvesting a conventional elliptical flap with providing satisfactory functional outcomes and near-normal contour, volume, and sensibility.
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Affiliation(s)
- Mohamed A Ellabban
- Plastic and Reconstructive Surgery Unit, Department of Surgery, Faculty of Medicine, Suez Canal University, Ismailia, Egypt
| | - Malek A Elsayed
- Plastic and Reconstructive Surgery Unit, Department of Surgery, Faculty of Medicine, Suez Canal University, Ismailia, Egypt
| | - Abo Bakr Zein
- Department of Orthopaedic Surgery and Traumatology, Faculty of Medicine, Cairo University, Giza, Egypt
| | - Mohamed Ghorab
- Department of Maxillofacial Surgery, Faculty of Dentistry, Cairo University, Giza, Egypt
| | - Moustafa Elmasry
- Department of Hand Surgery, Plastic Surgery and Burns, and Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Suhail Masadeh
- Podiatric Surgery Unit, Department of Surgery, University of Cincinnati, Cincinnati, Ohio, USA
| | - Mohamed Mokhtar Abo-Ella
- Department of Orthopaedic Surgery and Traumatology, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - Ahmed Fathy Sadek
- Department of Orthopaedic Surgery and Traumatology, Faculty of Medicine, Minia University, Minya, Egypt
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16
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Schimpf DJ, Ewert MM, Lai VK, Clarke BL. Responses of ticks to immersion in hot bathing water: Effect of surface type, water temperature, and soap on tick motor control. PLoS One 2021; 16:e0261592. [PMID: 34919573 PMCID: PMC8682875 DOI: 10.1371/journal.pone.0261592] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 12/03/2021] [Indexed: 11/22/2022] Open
Abstract
Preventing bites from undetected ticks through bathing practices would benefit public health, but the effects of these practices have been researched minimally. We immersed nymphal and adult hard ticks of species common in the eastern United States in tap water, using temperatures and durations that are realistic for human hot bathing. The effect of (a) different skin-equivalent surfaces (silicone and pig skin), and (b) water temperature was tested on Amblyomma americanum, Dermacentor variabilis and Ixodes scapularis nymphs. Overall, the type of surface had a much larger effect on the nymphs’ tendency to stay in contact with the surface than water temperature did. Most nymphs that separated from the surface did so within the first 10 s of immersion, with the majority losing contact due to the formation of an air bubble between their ventral side and the test surface. In addition, adult Ixodes scapularis were tested for the effect of immersion time, temperature, and soap on tick responsiveness. Some individual adults moved abnormally or stopped moving as a result of longer or hotter immersion, but soap had little effect on responsiveness. Taken together, our results suggest that the surface plays a role in ticks’ tendency to stay in contact; the use of different bath additives warrants further research. While water temperature did not have a significant short-term effect on tick separation, ticks that have not attached by their mouth parts may be rendered unresponsive and eventually lose contact with a person’s skin in a hot bath. It should be noted that our research did not consider potential temperature effects on the pathogens themselves, as previous research suggests that some tickborne pathogens may become less hazardous even if the tick harboring them survives hot-water exposures and later bites the bather after remaining undetected.
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Affiliation(s)
- David J. Schimpf
- Department of Biology, University of Minnesota – Duluth, Duluth, Minnesota, United States of America
| | - Matthew M. Ewert
- Department of Chemical Engineering, University of Minnesota – Duluth, Duluth, Minnesota, United States of America
| | - Victor K. Lai
- Department of Chemical Engineering, University of Minnesota – Duluth, Duluth, Minnesota, United States of America
- * E-mail:
| | - Benjamin L. Clarke
- Department of Biomedical Sciences, University of Minnesota – Duluth, Duluth, Minnesota, United States of America
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Fracture behaviour of human skin in deep needle insertion can be captured using validated cohesive zone finite-element method. Comput Biol Med 2021; 139:104982. [PMID: 34749097 DOI: 10.1016/j.compbiomed.2021.104982] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 10/10/2021] [Accepted: 10/23/2021] [Indexed: 11/24/2022]
Abstract
Medical needles have shown an appreciable contribution to the development of novel medical devices and surgical technologies. A better understanding of needle-skin interactions can advance the design of medical needles, modern surgical robots, and haptic devices. This study employed finite element (FE) modelling to explore the effect of different mechanical and geometrical parameters on the needle's force-displacement relationship, the required force for the skin puncture, and generated mechanical stress around the cutting zone. To this end, we established a cohesive FE model, and identified its parameters by a three-stage parameter identification algorithm to closely replicate the experimental data of needle insertion into the human skin available in the literature. We showed that a bilinear cohesive model with initial stiffness of 5000 MPa/mm, failure traction of 2 MPa, and separation length of 1.6 mm can lead to a model that can closely replicate experimental results. The FE results indicated that while the coefficient of friction between the needle and skin substantially changes the needle reaction force, the insertion velocity does not have a noticeable effect on the reaction force. Regarding the geometrical parameters, needle cutting angle is the prominent factor in terms of stress fields generated in the skin tissue. However, the needle diameter is more influential on the needle reaction force. We also presented an energy study on the frictional dissipation, damage dissipation, and strain energy throughout the insertion process.
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18
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Tang KPM, Yick KL, Li PL, Yip J, Or KH, Chau KH. Effect of Contacting Surface on the Performance of Thin-Film Force and Pressure Sensors. SENSORS 2020; 20:s20236863. [PMID: 33266213 PMCID: PMC7729666 DOI: 10.3390/s20236863] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 11/28/2020] [Accepted: 11/28/2020] [Indexed: 11/30/2022]
Abstract
Flexible force and pressure sensors are important for assessing the wear comfort of tightly fitting apparel. Their accuracy and repeatability depend on the sensor itself and the contacting surface. Measurements of the contact pressure on soft surfaces like human skin tend to be erroneous, which could be due to incorrect sensor calibrations. This study aims to examine the effects of human body parameters such as the hardness and temperature of the contacting surface by using a custom-made calibration setup and investigating the incorporation of rigid discs on the sensor surface. Two commercial force sensors, FlexiForce and SingleTact, and one pressure sensor, Pliance X, are used in the investigation. The findings reveal that adding rigid discs on both sides of the force sensors improves their sensitivity. Systematic calibration has been performed on the surfaces with different temperatures and hardness. The results show that FlexiForce and Pliance X tend to be affected by the changes in surface temperature and surface hardness. Prolonged testing time shows that the time dependence of SingleTact and Pliance X sensor is lower, which suggests that they are more suitable for lengthier evaluations in which interface pressure is exerted on the human body. In brief, sensor attachment and proper calibration should be thoroughly considered before using sensors for applications on soft surfaces, like the human body.
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Affiliation(s)
- Ka Po Maggie Tang
- Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Hong Kong; (K.P.M.T.); (P.L.L.); (J.Y.); (K.H.O.); (K.H.C.)
| | - Kit Lun Yick
- Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Hong Kong; (K.P.M.T.); (P.L.L.); (J.Y.); (K.H.O.); (K.H.C.)
- Laboratory for Artificial Intelligence in Design, Hong Kong Science Park, Taipo, Hong Kong
- Correspondence:
| | - Pui Ling Li
- Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Hong Kong; (K.P.M.T.); (P.L.L.); (J.Y.); (K.H.O.); (K.H.C.)
| | - Joanne Yip
- Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Hong Kong; (K.P.M.T.); (P.L.L.); (J.Y.); (K.H.O.); (K.H.C.)
| | - King Hei Or
- Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Hong Kong; (K.P.M.T.); (P.L.L.); (J.Y.); (K.H.O.); (K.H.C.)
| | - Kam Hong Chau
- Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hung Hom, Hong Kong; (K.P.M.T.); (P.L.L.); (J.Y.); (K.H.O.); (K.H.C.)
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Quinlan J, Yohay J, Subramanian V, Poziembo B, Fatone S. Using mechanical testing to assess the effect of lower-limb prosthetic socket texturing on longitudinal suspension. PLoS One 2020; 15:e0237841. [PMID: 32813733 PMCID: PMC7437898 DOI: 10.1371/journal.pone.0237841] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 07/27/2020] [Indexed: 11/18/2022] Open
Abstract
To function effectively, a lower limb prosthetic socket must remain securely coupled to the residual limb during walking, running and other activities of daily living; this coupling is referred to as suspension. When this coupling is insufficient longitudinal pistoning of the socket relative to the residual limb occurs. Increasing friction of the socket/liner interface may improve socket suspension and textured sockets may be fabricated relatively easily with 3D printing. The aim of this study was to investigate longitudinal displacement of sockets with different types of textures under two suspension conditions: passive suction and active vacuum. In order to do this, we developed a mock residual limb and mechanical testing protocol. Prosthetic sockets, 14 textured sockets and an Original Squirt-Shape (OSS) Socket, were fabricated from polypropylene copolymer using the Squirt-Shape™ 3D Printer and compared to a smooth socket thermoformed from polypropylene copolymer. Sockets were mounted onto a dual durometer mock residual limb and subjected to four levels of distraction forces (100 N, 250 N, 500 N and 650 N) using a hydraulic material testing system. There was a statistically significant three-way interaction between suspension, force level and texture (p < 0.0005). Longitudinal displacements between textured and reference sockets, for all force levels and both suspension conditions, were significantly different (p < 0.0005). Using these newly developed mechanical testing protocols, it was demonstrated that texturing of polypropylene copolymer sockets fabricated using Squirt-Shape significantly decreased longitudinal displacements compared to a smooth socket. However, none of the novel textured sockets significantly reduced longitudinal displacement compared to the OSS socket under passive suction suspension.
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Affiliation(s)
- Julia Quinlan
- Department of Physical Medicine and Rehabilitation, Northwestern University Prosthetics-Orthotics Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Jessica Yohay
- Department of Physical Medicine and Rehabilitation, Northwestern University Prosthetics-Orthotics Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Vasanth Subramanian
- Department of Physical Medicine and Rehabilitation, Northwestern University Prosthetics-Orthotics Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Brad Poziembo
- Prosthetic Design Inc, Dayton, Ohio, United States of America
| | - Stefania Fatone
- Department of Physical Medicine and Rehabilitation, Northwestern University Prosthetics-Orthotics Center, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- * E-mail:
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20
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Using mechanical testing to assess texturing of prosthetic sockets to improve suspension in the transverse plane and reduce rotation. PLoS One 2020; 15:e0233148. [PMID: 32525868 PMCID: PMC7289418 DOI: 10.1371/journal.pone.0233148] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 04/28/2020] [Indexed: 11/21/2022] Open
Abstract
Creating a secure and comfortable linkage between the residual limb and prosthetic socket in persons with lower limb amputation is a critical factor for successful rehabilitation, including ambulation and other activities of daily living. Unwanted rotation within the socket can be a clinical problem for prosthesis users. One way of addressing issues experienced with transverse plane control of the socket may be through increased friction interface forces. It has been proposed that friction at the residual limb/socket interface may be increased by adding texture to interface components. Three-dimensional (3D) printing may be used to fabricate sockets with texture patterns added to the inner socket surface. Hence, the aim of this study was to investigate the effects of socket texturing on transverse plane rotation of the socket on a mock residual limb under two suspension conditions: passive suction and active vacuum. To conduct this study, we developed a mechanical testing protocol as no standardized tests currently exist to assess prosthetic sockets. Sockets with 14 different texture patterns were fabricated using the Squirt-Shape™ 3D printer. Textured sockets were compared to an Original Squirt-Shape (OSS) socket and a smooth thermoformed socket. Sockets were fitted with a mock residual limb and bi-axially loaded to 350 N compression with simultaneous rotation (2.5°, 5° and 7.5°) using a custom rotation assembly attached to a uniaxial hydraulic material testing system. There was a statistically significant three-way interaction between suspension, angle and texture (p < 0.0005). Torques between textured and reference sockets, for all rotation angles and both suspension conditions, were significantly different (p < 0.0005). Using newly developed testing protocols, it was demonstrated that some texture patterns significantly increased torque (i.e., resistance against unwanted rotation) in the transverse plane compared to both OSS and smooth sockets, especially for passive suction. Rotation testing of sockets may provide insight into socket design to improve suspension in the transverse plane.
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21
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Yan J, Yan S, Tilly JC, Ko Y, Lee B, Spontak RJ. Ionic complexation of endblock-sulfonated thermoplastic elastomers and their physical gels for improved thermomechanical performance. J Colloid Interface Sci 2020; 567:419-428. [PMID: 32088505 DOI: 10.1016/j.jcis.2020.02.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2020] [Revised: 02/02/2020] [Accepted: 02/03/2020] [Indexed: 11/20/2022]
Abstract
Thermoplastic elastomers (TPEs) composed of nonpolar triblock copolymers constitute a broadly important class of (re)processable network-forming macromolecules employed in ubiquitous commercial applications. Physical gelation of these materials in the presence of a low-volatility oil that is midblock-selective yields tunably soft TPE gels (TPEGs) that are suitable for emergent technologies ranging from electroactive, phase-change and shape-memory responsive media to patternable soft substrates for flexible electronics and microfluidics. Many of the high-volume TPEs used for these purposes possess styrenic endblocks that are inherently limited by a relatively low glass transition temperature. To mitigate this shortcoming, we sulfonate and subsequently complex (and physically crosslink) the endblocks with trivalent Al3+ ions. Doing so reduces the effective hydrophilicity of the sulfonated endblocks, as evidenced by water uptake measurements, while concurrently enhancing the thermomechanical stability of the corresponding TPEGs. Chemical modification results, as well as morphological and property development, are investigated as functions of the degree of sulfonation, complexation and TPEG composition.
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Affiliation(s)
- Jiaqi Yan
- Department of Chemical & Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695, USA
| | - Shaoyi Yan
- Department of Materials Science & Engineering, North Carolina State University, Raleigh, NC 27695, USA
| | - Joseph C Tilly
- Department of Chemical & Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695, USA
| | - Yeongun Ko
- Department of Chemical & Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695, USA
| | - Byeongdu Lee
- Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Richard J Spontak
- Department of Chemical & Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695, USA; Department of Materials Science & Engineering, North Carolina State University, Raleigh, NC 27695, USA.
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22
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Zhang L, Jackson WJ, Bentil SA. The mechanical behavior of brain surrogates manufactured from silicone elastomers. J Mech Behav Biomed Mater 2019; 95:180-190. [PMID: 31009902 DOI: 10.1016/j.jmbbm.2019.04.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 03/03/2019] [Accepted: 04/05/2019] [Indexed: 01/05/2023]
Abstract
The ongoing conflict against terrorism has resulted in an escalation of blast-induced traumatic brain injuries (bTBI) caused by improvised explosive devices (IEDs). The destructive IEDs create a blast wave that travels through the atmosphere. Blast-induced traumatic brain injuries, attributed to the blast wave, can cause life-threatening injuries and fatalities. This study aims to find a surrogate brain material for assessing the effectiveness of head protection systems designed to mitigate bTBI. Polydimethylsiloxane (PDMS) is considered as the surrogate brain material. The stiffness of PDMS (Sylgard 184, Dow Corning Corp.) can be controlled by varying the ratio of base and curing agent. Cylindrical PDMS specimen with ratios of 1:10, 1:70, and 1:80 were subjected to unconfined compression experiments at linear rates of 5 mm/min, 50 mm/min, and 500 mm/min. A ramp-hold strain profile was used to simulate a stress relaxation experiment. The fractional Zener viscoelastic model was used to describe the stress relaxation response, after optimization of the material constants for the brain surrogate and shock wave exposure brain tissue. The results show that the low cost PDMS can be used as a surrogate brain material to study the dynamic brain response to blast wave exposure.
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Affiliation(s)
- Ling Zhang
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 2529 Union Drive, Ames, IA, 50011, USA
| | - William J Jackson
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 2529 Union Drive, Ames, IA, 50011, USA
| | - Sarah A Bentil
- Department of Mechanical Engineering, Iowa State University of Science and Technology, 2529 Union Drive, Ames, IA, 50011, USA.
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Chanda A, McClain S. Mechanical Modeling of Healthy and Diseased Calcaneal Fat Pad Surrogates. Biomimetics (Basel) 2019; 4:E1. [PMID: 31105187 PMCID: PMC6477669 DOI: 10.3390/biomimetics4010001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 11/16/2018] [Accepted: 12/19/2018] [Indexed: 11/16/2022] Open
Abstract
The calcaneal fat pad is a major load bearing component of the human foot due to daily gait activities such as standing, walking, and running. Heel and arch pain pathologies such as plantar fasciitis, which over one third of the world population suffers from, is a consequent effect of calcaneal fat pad damage. Also, fat pad stiffening and ulceration has been observed due to diabetes mellitus. To date, the biomechanics of fat pad damage is poorly understood due to the unavailability of live human models (because of ethical and biosafety issues) or biofidelic surrogates for testing. This also precludes the study of the effectiveness of preventive custom orthotics for foot pain pathologies caused due to fat pad damage. The current work addresses this key gap in the literature with the development of novel biofidelic surrogates, which simulate the in vivo and in vitro compressive mechanical properties of a healthy calcaneal fat pad. Also, surrogates were developed to simulate the in vivo mechanical behavior of the fat pad due to plantar fasciitis and diabetes. A four-part elastomeric material system was used to fabricate the surrogates, and their mechanical properties were characterized using dynamic and cyclic load testing. Different strain (or displacement) rates were tested to understand surrogate behavior due to high impact loads. These surrogates can be integrated with a prosthetic foot model and mechanically tested to characterize the shock absorption in different simulated gait activities, and due to varying fat pad material property in foot pain pathologies (i.e., plantar fasciitis, diabetes, and injury). Additionally, such a foot surrogate model, fitted with a custom orthotic and footwear, can be used for the experimental testing of shock absorption characteristics of preventive orthoses.
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Affiliation(s)
- Arnab Chanda
- Department of Bioengineering, University of Pittsburgh, PA 15213, USA.
- Department of Aerospace Engineering and Mechanics, University of Alabama, AL 35401, USA.
| | - Stephen McClain
- Department of Aerospace Engineering and Mechanics, University of Alabama, AL 35401, USA.
- Department of Biomedical Engineering, Georgia Institute of Technology, GA 30332, USA.
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Chanda A, Ruchti T, Upchurch W. Biomechanical Modeling of Prosthetic Mesh and Human Tissue Surrogate Interaction. Biomimetics (Basel) 2018; 3:E27. [PMID: 31105249 PMCID: PMC6352698 DOI: 10.3390/biomimetics3030027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 09/09/2018] [Accepted: 09/13/2018] [Indexed: 11/30/2022] Open
Abstract
Surgical repair of hernia and prolapse with prosthetic meshes are well-known to cause pain, infection, hernia recurrence, and mesh contraction and failures. In literature, mesh failure mechanics have been studied with uniaxial, biaxial, and cyclic load testing of dry and wet meshes. Also, extensive experimental studies have been conducted on surrogates, such as non-human primates and rodents, to understand the effect of mesh stiffness, pore size, and knitting patterns on mesh biocompatibility. However, the mechanical properties of such animal tissue surrogates are widely different from human tissues. Therefore, to date, mechanics of the interaction between mesh and human tissues is poorly understood. This work addresses this gap in literature by experimentally and computationally modeling the biomechanical behavior of mesh, sutured to human tissue phantom under tension. A commercially available mesh (Prolene®) was sutured to vaginal tissue phantom material and tested at different uniaxial strains and strain rates. Global and local stresses at the tissue phantom, suture, and mesh were analyzed. The results of this study provide important insights into the mechanics of prosthetic mesh failure and will be indispensable for better mesh design in the future.
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Affiliation(s)
- Arnab Chanda
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15213, USA.
- Department of Aerospace Engineering and Mechanics, University of Alabama, Tuscaloosa, AL 35401, USA.
| | - Tysum Ruchti
- Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602, USA.
| | - Weston Upchurch
- Department of Aerospace Engineering and Mechanics, University of Alabama, Tuscaloosa, AL 35401, USA.
- Department of Surgery, University of Minnesota, Minneapolis, MN 55455, USA.
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