Design of a Handheld Tissue Grasping Device to Measure Tissue Mechanical Properties In-Vivo or in a Laboratory Setting

2020 ◽  
Author(s):  
Bradley Drahos ◽  
Amer Safdari ◽  
Faizan Malik ◽  
Rebecca Smith ◽  
Matt Kubala ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Response ◽  
Angular Position ◽  
Compressive Force ◽  
Data File ◽  
Ex Situ ◽  
Laboratory Setting ◽  
Handheld Device ◽  
Live Feed

Abstract With medical institutions increasing the use of medical simulators for educational purposes it is detrimental that the knowledge gap regarding tissue mechanical properties be researched further in depth. The grasper device discussed throughout this paper aims to provide researchers a handheld device capable of testing soft organs and tissue in-vivo and ex-situ in a laboratory setting. The device consists of two load cells on the inner jaws of the grasper to measure compressive force and an encoder to monitor the graspers angular position which yields tissue position and strain. Accompanying the grasper is a GUI written in Rust which is capable of data file management, and providing a 10 second live feed of load cell and encoder readings. The grasper device is currently being employed in a study testing the tissue mechanical response of porcine tissue at states ranging from in-vivo to ex-situ post freeze. The results from this test, and subsequent tests using the grasper have the capability of providing much needed knowledge regarding tissue mechanical properties to improve medical simulators and medical education as a whole.

In-Vivo Mechanical Properties of Soft Tissue Covering Bony Prominences

1978 ◽  
Vol 100 (4) ◽  
pp. 194-201 ◽  
Author(s):  
J. C. Ziegert ◽  
J. L. Lewis
Keyword(s):  
Mechanical Properties ◽  
Soft Tissue ◽  
Dynamic Loading ◽  
Static Loading ◽  
Mechanical Response ◽  
Bony Prominence ◽  
Soft Tissue Covering

In order to measure in-vivo bone accelerations, it is necessary to know the mechanical response of the soft tissue covering areas of bony prominence when a load is applied through a rigid contactor. Two methods are presented for determining this response in vivo. The first method is for quasi-static loading and the second method is for dynamic loading at approximately 2000 Hz. Results are presented for various subjects and contactor geometries.

Corrigendum to: Elastic properties of the forisome

2007 ◽  
Vol 34 (11) ◽  
pp. 1053
Author(s):  
Stephen A. Warmann ◽  
William F. Pickard ◽  
Amy Q. Shen
Keyword(s):  
Mechanical Properties ◽  
Radial Direction ◽  
Mechanical Response ◽  
Viscoelastic Model ◽  
Strain Curve ◽  
Longitudinal Direction ◽  
Tensile Tests ◽  
Before And After

Forisomes are elongate Ca2+-responsive contractile protein bodies and act as flow blocking gates within the phloem of legumes. Because an understanding of their mechanical properties in vitro underpins understanding of their physiology in vivo, we undertook, using a microcantilever method, microscopic tensile tests (incremental stress-relaxation measurements) on forisomes from Canavalia gladiata (Jacq.) DC Akanata Mame and Vicia faba L. Witkiem Major. Viscoelastic properties of forisomes in their longitudinal direction were investigated before and after Ca2+-induced contraction, but in the radial direction only before contraction. Forisomes showed mechanical properties typical of a biological material with a unidirectional fibrous structure, i.e. the modulus of elasticity in the direction of their fibers is much greater than in the radial direction. Creep data were collected in all tensile tests and fit with a three parameter viscoelastic model. The pre-contraction longitudinal elastic moduli of the forisomes were not differentiable between the two species (V. faba, 660���360�kPa; C. gladiata, 600���360�kPa). Both species showed a direction-dependent mechanical response: the elastic modulus was dramatically smaller in the radial direction than in the longitudinal direction, suggesting a weak protein cross-linking amongst longitudinal protein fibers. Activation of forisomes decreased forisome stiffness longitudinally, as evidenced by the loss of toe-region in the stress strain curve, suggesting that the forisome may have dispersed or disordered its protein structure in a controlled fashion. Contractile forces generated by single forisomes undergoing activation were also measured for V. faba (510���390�nN) and C. gladiata (570���310�nN).

Mechanical Properties of Biomimetic Composites for Bone Tissue Engineering

2004 ◽  
Vol 844 ◽  
Author(s):  
Devendra Verma ◽  
Kalpana S. Katti ◽  
Bedabibhas Mohanty
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Elastic Modulus ◽  
Bone Tissue Engineering ◽  
Bone Tissue ◽  
Mechanical Response ◽  
Structural Disorder ◽  
Ex Situ ◽  
Porous Composites

ABSTRACTA biomimetic process involving in situ mineralization of hydroxyapatite (HAP) is used to design new composite biomaterials for bone tissue engineering. Surface and bulk properties of HAP composites have been studied for hydroxyapatite mineralized in absence (ex situ) of polyacrylic acid (PAAc) and in presence (in situ) of PAAc. XRD studies show existence of structural disorder within in situ HAP. It has been observed that PAAc increases the rate of crystallization. FTIR studies indicate calcium deficiency in structure of both in situ and ex situ HAP. PAAc provides favorable sites for nucleation of HAP. During crystallization of HAP, PAAc dissociates to form carboxylate ion, which binds to HAP. Porous and solid composites of in situ and ex situ HAP with polycaprolactone (PCL) in 50:50 ratio have been made to evaluate their applicability as bone scaffold. Mechanical tests on solid samples indicate ex situ HAP/PCL composites have higher elastic modulus (1.16 GPa) than in situ HAP/PCL composites (0.82 GPa). However, in case of porous composites, in situ HAP/PCL composites are found to have higher elastic modulus (29.5 MPa) than ex situ HAP/PCL composites (10.4 MPa). Nanoindentation tests were also performed at different loads to evaluate mechanical properties of the composites. In situ HAP mineralized using non-degradable polymers has thus been shown to improve mechanical response in porous composites.

Elastic properties of the forisome

2007 ◽  
Vol 34 (10) ◽  
pp. 935 ◽  
Author(s):  
Stephen A. Warmann ◽  
William F. Pickard ◽  
Amy Q. Shen
Keyword(s):  
Mechanical Properties ◽  
Radial Direction ◽  
Mechanical Response ◽  
Viscoelastic Model ◽  
Strain Curve ◽  
Longitudinal Direction ◽  
Tensile Tests ◽  
Before And After

Forisomes are elongate Ca2+-responsive contractile protein bodies and act as flow blocking gates within the phloem of legumes. Because an understanding of their mechanical properties in vitro underpins understanding of their physiology in vivo, we undertook, using a microcantilever method, microscopic tensile tests (incremental stress-relaxation measurements) on forisomes from Canavalia gladiata (Jacq.) DC Akanata Mame and Vicia faba L. Witkiem Major. Viscoelastic properties of forisomes in their longitudinal direction were investigated before and after Ca2+-induced contraction, but in the radial direction only before contraction. Forisomes showed mechanical properties typical of a biological material with a unidirectional fibrous structure, i.e. the modulus of elasticity in the direction of their fibers is much greater than in the radial direction. Creep data were collected in all tensile tests and fit with a three parameter viscoelastic model. The pre-contraction longitudinal elastic moduli of the forisomes were not differentiable between the two species (V. faba, 660 ± 360 kPa; C. gladiata, 600 ± 360 kPa). Both species showed a direction-dependent mechanical response: the elastic modulus was dramatically smaller in the radial direction than in the longitudinal direction, suggesting a weak protein cross-linking amongst longitudinal protein fibers. Activation of forisomes decreased forisome stiffness longitudinally, as evidenced by the loss of toe-region in the stress strain curve, suggesting that the forisome may have dispersed or disordered its protein structure in a controlled fashion. Contractile forces generated by single forisomes undergoing activation were also measured for V. faba (510 ± 390 nN) and C. gladiata (570 ± 310 nN).

Substrate Dependence of Mechanical Response of Neurons and Astrocytes

2011 ◽  
Author(s):  
Kristin B. Bernick ◽  
Simona Socrate
Keyword(s):  
Mechanical Properties ◽  
Mechanical Response ◽  
Imaging Techniques ◽  
Cell Types ◽  
Confocal Imaging ◽  
Cell Stiffness ◽  
Large Strains ◽  
Neural Cells ◽  
Mechanical Stimuli

The response of neural cells to mechanical cues is a critical component of the innate neuroprotective cascade aimed at minimizing the consequences of traumatic brain injury (TBI). Reactive gliosis and the formation of glial scars around the lesion site are among the processes triggered by TBI where mechanical stimuli play a central role. It is well established that the mechanical properties of the microenvironment influence phenotype and morphology in most cell types. It has been shown that astrocytes change morphology [1] and cytoskeletal content [2] when grown on substrates of varying stiffness, and that mechanically injured astrocyte cultures show alterations in cell stiffness [3]. Accurate estimates of the mechanical properties of central nervous system (CNS) cells in their in-vivo conditions are needed to develop multiscale models of TBI. Lu et al found astrocytes to be softer than neurons under small deformations [4]. In recent studies, we investigated the response of neurons to large strains and at different loading rates in order to develop single cell models capable of simulating cell deformations in regimes relevant for TBI conditions [5]. However, these studies have been conducted on cells cultured on hard substrates, and the measured cell properties might differ from their in-vivo counterparts due to the aforementioned effects. Here, in order to investigate the effects of substrate stiffness on the cell mechanical properties, we used atomic force microscopy (AFM) and confocal imaging techniques to characterize the response of primary neurons and astrocytes cultured on polyacrylamide (PAA) gels of varying composition. The use of artificial gels minimizes confounding effects associated with biopolymer gels (both protein-based and polysaccharide-based) where specific receptor bindings may trigger additional biochemical responses [1].

Skin Viscoelasticity Under Hypothermic Temperatures

2008 ◽  
Author(s):  
Feng Xu ◽  
Tianjian Lu
Keyword(s):  
Mechanical Properties ◽  
Thermal Loading ◽  
Mechanical Response ◽  
Skin Tissue ◽  
Skin Area ◽  
Physiological Conditions ◽  
Recent Developments ◽  
Surrounding Healthy Tissue

Advances in electromagnetic technologies have led to recent developments in thermal treatments of diseased and injured skin tissue. These thermal treatment methods normally involve either a raising or lowering of temperature in targeted skin area to kill or thermally denaturize the necrotic cells but without affecting the surrounding, healthy tissue. It is proposed that a detailed understanding of the coupled biological-mechanical response under thermal loading will contribute to the design, characterization and optimization of strategies for delivering better treatments. Since it is technically very difficult to measure experimentally the bio-thermo-mechanical behaviour of skin tissue in physiological conditions, analytical and numerical simulations are used, where the quantification of the skin mechanical properties is an essential step towards building reliable computer simulations. So far, the mechanical properties of the skin tissue under normal physiological conditions have been studied experimentally a lot both in vivo and in vitro. However, little has been done on characterization of the mechanical properties of skin tissue under hypothermic conditions, which will be addressed in this study.

The Role of Mechanical Tension in Neurons

2010 ◽  
Vol 1274 ◽  
Author(s):  
Taher Saif ◽  
Jagannathan Rajagopalan ◽  
Alireza Tofangchi
Keyword(s):  
Mechanical Response ◽  
Mechanical Forces ◽  
Active Tension ◽  
Mechanical Tension ◽  
Deformation Response ◽  
Linear Force ◽  
Tension Regulation ◽  
Over Time

AbstractWe used high resolution micromechanical force sensors to study the in vivo mechanical response of embryonic Drosophila neurons. Our experiments show that Drosophila axons have a rest tension of a few nN and respond to mechanical forces in a manner characteristic of viscoelastic solids. In response to fast externally applied stretch they show a linear force-deformation response and when the applied stretch is held constant the force in the axons relaxes to a steady state value over time. More importantly, when the tension in the axons is suddenly reduced by releasing the external force the neurons actively restore the tension, sometimes close to their resting value. Along with the recent findings of Siechen et al (Proc. Natl. Acad. Sci. USA 106, 12611 (2009)) showing a link between mechanical tension and synaptic plasticity, our observation of active tension regulation in neurons suggest an important role for mechanical forces in the functioning of neurons in vivo.

scholarly journals Concomitant control of mechanical properties and degradation in resorbable elastomer-like materials using stereochemistry and stoichiometry for soft tissue engineering

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Mary Beth Wandel ◽  
Craig A. Bell ◽  
Jiayi Yu ◽  
Maria C. Arno ◽  
Nathan Z. Dreger ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Drug Delivery ◽  
Soft Tissue ◽  
Tissue Regeneration ◽  
Biological Tissues ◽  
Soft Tissue Regeneration ◽  
Soft Tissue Engineering ◽  
Degradation Properties ◽  
Enhance Cell Adhesion

AbstractComplex biological tissues are highly viscoelastic and dynamic. Efforts to repair or replace cartilage, tendon, muscle, and vasculature using materials that facilitate repair and regeneration have been ongoing for decades. However, materials that possess the mechanical, chemical, and resorption characteristics necessary to recapitulate these tissues have been difficult to mimic using synthetic resorbable biomaterials. Herein, we report a series of resorbable elastomer-like materials that are compositionally identical and possess varying ratios of cis:trans double bonds in the backbone. These features afford concomitant control over the mechanical and surface eroding degradation properties of these materials. We show the materials can be functionalized post-polymerization with bioactive species and enhance cell adhesion. Furthermore, an in vivo rat model demonstrates that degradation and resorption are dependent on succinate stoichiometry in the elastomers and the results show limited inflammation highlighting their potential for use in soft tissue regeneration and drug delivery.

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