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Shrestha P, Geffner C, Jaffey M, Wu Z, Iapichino M, Bacca M, Stoeber B. Force decomposition and toughness estimation from puncture experiments in soft solids. SOFT MATTER 2024; 20:5377-5388. [PMID: 38932556 DOI: 10.1039/d4sm00211c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/28/2024]
Abstract
Several medical applications, like drug delivery and biosensing, are critically preceded by the insertion of needles and microneedles into biological tissue. However, the mechanical process of needle insertions, especially at high velocities, is currently not fully understood. Here, we explore the insertion of hollow needles into transparent silicone samples with an insertion velocity v ranging from 0.1 mm s-1 to 2.3 m s-1 (with needle radius R = 101.5 μm, thus strain rates ∼v/R ranging from 1 s-1 to 2.3 × 104 s-1). We use a double-insertion method, where the needle is inserted and re-inserted at the same location, to estimate the fracture properties of the material. The deflection of the specimen's free surface is found to be different between insertion and re-insertion experiments for identical needle positions, which is associated with different force magnitudes between insertion/reinsertion. This aspect was previously neglected in the original double-insertion method, thus here we develop a method based on imaging, image analyses and force measurements to decompose the measured force into individual force components, including deflection force Fd, frictional and spreading force Ff + Fs, and cutting force Ft. We estimate that the toughness Γ of our silicone samples, calculated using the cutting force Ft and the crack dimensions, increases with needle velocity, and ranges within observed values in previous literature for the same material and for some soft biological materials. In addition to toughness Γ, other parameters, such as critical force Fc and mechanical work Wc, also show strain-rate dependence, suggesting tissue stiffening, due to accumulated strain energy, at high speeds.
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Affiliation(s)
- Pranav Shrestha
- Department of Mechanical Engineering, The University of British Columbia, 2054-6250 Applied Science Lane, Vancouver, British Columbia, V6T 1Z4, Canada.
| | - Curtis Geffner
- Department of Mechanical Engineering, The University of British Columbia, 2054-6250 Applied Science Lane, Vancouver, British Columbia, V6T 1Z4, Canada.
| | - Matthew Jaffey
- Department of Mechanical Engineering, The University of British Columbia, 2054-6250 Applied Science Lane, Vancouver, British Columbia, V6T 1Z4, Canada.
| | - Zhongnan Wu
- Department of Mechanical Engineering, The University of British Columbia, 2054-6250 Applied Science Lane, Vancouver, British Columbia, V6T 1Z4, Canada.
| | - Martina Iapichino
- Department of Mechanical Engineering, The University of British Columbia, 2054-6250 Applied Science Lane, Vancouver, British Columbia, V6T 1Z4, Canada.
| | - Mattia Bacca
- Department of Mechanical Engineering, The University of British Columbia, 2054-6250 Applied Science Lane, Vancouver, British Columbia, V6T 1Z4, Canada.
| | - Boris Stoeber
- Department of Mechanical Engineering, The University of British Columbia, 2054-6250 Applied Science Lane, Vancouver, British Columbia, V6T 1Z4, Canada.
- Department of Electrical and Computer Engineering, The University of British Columbia, 2332 Main Mall, Vancouver, British Columbia, V6T 1Z4, Canada
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2
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Barney CW, Berezvai S, Chau AL, Kwon Y, Pitenis AA, McMeeking RM, Valentine MT, Helgeson ME. Experimental observation of near-wall effects during the puncture of soft solids. SOFT MATTER 2024; 20:3806-3813. [PMID: 38646972 DOI: 10.1039/d3sm01216f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Performing conventional mechanical characterization techniques on soft materials can be challenging due to issues such as limited sample volumes and clamping difficulties. Deep indentation and puncture is a promising alternative as it is an information-rich measurement with the potential to be performed in a high-throughput manner. Despite its promise, the method lacks standardized protocols, and open questions remain about its possible limitations. Addressing these shortcomings is vital to ensure consistent methodology, measurements, and interpretation across samples and labs. To fill this gap, we examine the role of finite sample dimensions (and by extension, volume) on measured forces to determine the sample geometry needed to perform and unambiguously interpret puncture tests. Through measurements of puncture on a well-characterized elastomer using systematically varied sample dimensions, we show that the apparent mechanical response of a material is in fact sensitive to near-wall effects, and that additional properties, such as the sliding friction coefficient, can only be extracted in the larger dimension case where such effects are negligible.
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Affiliation(s)
- Christopher W Barney
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
| | - Szabolcs Berezvai
- Department of Applied Mechanics, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, Müegyetem rkp. 3., H-1111 Budapest, Hungary
| | - Allison L Chau
- Materials Department, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Younghoon Kwon
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
| | - Angela A Pitenis
- Materials Department, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Robert M McMeeking
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
- Materials Department, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Megan T Valentine
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
| | - Matthew E Helgeson
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
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Quan H, Liang X, Zhang X, Meyers MA, McMeeking RM, Arzt E. The shape of Nature's stingers revealed. Proc Natl Acad Sci U S A 2024; 121:e2316320121. [PMID: 38319966 PMCID: PMC10873632 DOI: 10.1073/pnas.2316320121] [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: 09/19/2023] [Accepted: 12/06/2023] [Indexed: 02/08/2024] Open
Abstract
Stinger-like structures in living organisms evolved convergently across taxa for both defensive and offensive purposes, with the main goal being penetration and damage. Our observations over a broad range of taxa and sizes, from microscopic radiolarians to narwhals, reveal a self-similar geometry of the stinger extremity: the diameter (d) increases along the distance from the tip (x) following a power law [Formula: see text] , with the tapering exponent varying universally between 2 and 3. We demonstrate, through analytical and experimental mechanics involving three-dimensional (3D) printing, that this geometry optimizes the stinger's performance; it represents a trade-off between the propensity to buckle, for n smaller than 2, and increased penetration force, for n greater than 3. Moreover, we find that this optimal tapering exponent does not depend on stinger size and aspect ratio (base diameter over length). We conclude that for Nature's stingers, composed of biological materials with moduli ranging from hundreds of megapascals to ten gigapascals, the necessity for a power-law contour increases with sharpness to ensure sufficient stability for penetration of skin-like tissues. Our results offer a solution to the puzzle underlying this universal geometric trait of biological stingers and may provide a new strategy to design needle-like structures for engineering or medical applications.
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Affiliation(s)
- Haocheng Quan
- Department of Materials Science and Engineering, College of Engineering and Applied Sciences, Nanjing University, Nanjing210023, China
- Institute for New Materials–Leibniz Institute for New Materials, Saarbrücken66123, Germany
| | - Xudong Liang
- School of Science, Harbin Institute of Technology, Shenzhen518055, China
| | - Xuan Zhang
- Department of Advanced Manufacturing and Robotics, College of Engineering, Peking University, Beijing100871, China
| | - Marc A. Meyers
- Department of Nanoengineering, University of California, San Diego, CA92093
| | - Robert M. McMeeking
- Institute for New Materials–Leibniz Institute for New Materials, Saarbrücken66123, Germany
- Departments of Materials and Mechanical Engineering, University of California, Santa Barbara, CA93106
| | - Eduard Arzt
- Institute for New Materials–Leibniz Institute for New Materials, Saarbrücken66123, Germany
- Department of Materials Science and Engineering, Saarland University, Saarbrücken66123, Germany
- Department of Mechanical and Aerospace Engineering, Program in Materials Science and Engineering, University of California, San Diego, CA92093
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4
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Fregonese S, Bacca M. How friction and adhesion affect the mechanics of deep penetration in soft solids. SOFT MATTER 2022; 18:6882-6887. [PMID: 36043847 DOI: 10.1039/d2sm00638c] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The mechanics of puncture and soft solid penetration is commonly explored with the assumption of frictionless contact between the needle (penetrator) and the specimen. This leads to the hypothesis of a constant penetration force. Experimental observations, however, report a linear increment of penetration force with needle tip depth. This force increment is due to friction and adhesion, and this paper provides its correlation with the properties of the cut material. Specifically, the force-depth slope depends on the rigidity and toughness of the soft material, the radius of the penetrator and the interfacial properties (friction and adhesion) between the two. We observe that adhesion prevails at relatively low toughness, while friction is dominant at high toughness. Finally, we compare our results with experiments and observe good agreement. Our model provides a valuable tool to predict the evolution of penetration force with depth and to measure the friction and adhesion characteristics at the needle-specimen interface from puncture experiments.
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Affiliation(s)
- Stefano Fregonese
- Mechanical Engineering Department, Institute of Applied Mathematics, School of Biomedical Engineering, University of British Columbia, Vancouver, BC V6T1Z4, Canada.
| | - Mattia Bacca
- Mechanical Engineering Department, Institute of Applied Mathematics, School of Biomedical Engineering, University of British Columbia, Vancouver, BC V6T1Z4, Canada.
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Barney CW, Valentine MT, Helgeson ME. Strength of fluid-filled soft composites across the elastofracture length. SOFT MATTER 2022; 18:4897-4904. [PMID: 35722727 DOI: 10.1039/d2sm00177b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Materials that utilize heterogeneous microstructures to control macroscopic mechanical response are ubiquitous in nature. Yet, translating nature's lessons to create synthetic soft solids has remained challenging. This is largely due to the limited synthetic routes available for creating soft composites, particularly with submicron features, as well as uncertainty surrounding the role of such a microstructured secondary phase in determining material behavior. This work leverages recent advances in the development of photocrosslinkable thermogelling nanoemulsions to produce composite hydrogels with a secondary phase assembled at well controlled length scales ranging from tens of nm to tens of μm. Through analysis of the mechanical response of these fluid-filled composite hydrogels, it is found that the size scale of the secondary phase has a profound impact on the strength when at or above the elastofracture length. Moreover, this work shows that mechanical integrity of fluid-filled soft solids can be sensitive to the size scale of the secondary phase.
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Affiliation(s)
- Christopher W Barney
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
| | - Megan T Valentine
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
| | - Matthew E Helgeson
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
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Bailey SJ, Barney CW, Sinha NJ, Pangali SV, Hawker CJ, Helgeson ME, Valentine MT, Read de Alaniz J. Rational mechanochemical design of Diels-Alder crosslinked biocompatible hydrogels with enhanced properties. MATERIALS HORIZONS 2022; 9:1947-1953. [PMID: 35575385 DOI: 10.1039/d2mh00338d] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
An important but often overlooked feature of Diels-Alder (DA) cycloadditions is the ability for DA adducts to undergo mechanically induced cycloreversion when placed under force. Herein, we demonstrate that the commonly employed DA cycloaddition between furan and maleimide to crosslink hydrogels results in slow gelation kinetics and "mechanolabile" crosslinks that relate to reduced material strength. Through rational computational design, "mechanoresistant" DA adducts were identified by constrained geometries simulate external force models and employed to enhance failure strength of crosslinked hydrogels. Additionally, utilization of a cyclopentadiene derivative, spiro[2.4]hepta-4,6-diene, provided mechanoresistant DA adducts and rapid gelation in minutes at room temperature. This study illustrates that strategic molecular-level design of DA crosslinks can provide biocompatible materials with improved processing, mechanical durability, lifetime, and utility.
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Affiliation(s)
- Sophia J Bailey
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
| | - Christopher W Barney
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
- Materials Research Laboratory, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Nairiti J Sinha
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
- Materials Research Laboratory, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Sai Venkatesh Pangali
- Center for Structural Molecular Biology, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Craig J Hawker
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
- Materials Research Laboratory, University of California Santa Barbara, Santa Barbara, CA 93106, USA
- Materials Department, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Matthew E Helgeson
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
- Materials Research Laboratory, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Megan T Valentine
- Department of Mechanical Engineering, University of California Santa Barbara, Santa Barbara, CA 93106, USA
- Materials Research Laboratory, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Javier Read de Alaniz
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
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Barney CW, Sacligil I, Tew GN, Crosby AJ. Linking cavitation and fracture to molecular scale structural damage of model networks. SOFT MATTER 2022; 18:4220-4226. [PMID: 35607851 DOI: 10.1039/d2sm00400c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Rapid expansion of soft solids subjected to a negative hydrostatic stress can occur through cavitation or fracture. Understanding how these two mechanisms relate to a material's molecular structure is important to applications in materials characterization, adhesive design, and tissue damage. Here, a recently improved needle-induced cavitation (NIC) protocol is applied to a set of model end-linked PEG gels with quantitatively linked elastic and fracture properties. This quantitative link between molecular scale structure and macroscopic properties is exploited to experimentally probe the relationship between cavitation, fracture, and molecular scale damage. This work indicates that rational tuning of the elastofracture length relative to the crack geometry can be used to alter the expansion mechanism from cavitation to fracture during NIC.
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Affiliation(s)
- Christopher W Barney
- Polymer Science & Engineering Department, University of Massachusetts, Amherst, MA 01003, USA.
| | - Ipek Sacligil
- Polymer Science & Engineering Department, University of Massachusetts, Amherst, MA 01003, USA.
| | - Gregory N Tew
- Polymer Science & Engineering Department, University of Massachusetts, Amherst, MA 01003, USA.
| | - Alfred J Crosby
- Polymer Science & Engineering Department, University of Massachusetts, Amherst, MA 01003, USA.
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M M, Bobji MS, Simha KRY. Cone cracks in tissue-mimicking hydrogels during hypodermic needle insertion: the role of water content. SOFT MATTER 2022; 18:3521-3530. [PMID: 35438127 DOI: 10.1039/d2sm00257d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Needle insertion into soft biological tissues is a common process in various surgical procedures. During insertion, soft biological tissues with different water contents undergo large deformation often leading to uncontrollable cracks and tissue damage. Despite the numerous experimental studies and numerical modelling of needle-tissue interaction, the results do not show any consistency mainly due to the heterogeneity of tissue properties and opaqueness. In this context, understanding the fracture behaviour of soft tissues during needle insertion is important for minimally invasive surgeries and other medical procedures. Recently, we showed that the needle insertion into a transparent, tissue-mimicking polyacrylamide (PAAm) hydrogel causes periodic cone cracks. In this work, we systematically varied the water content of the PAAm hydrogel in the preparation state and performed needle insertion experiments using a hypodermic needle at a constant velocity to study the fracture characteristics of the PAAm hydrogel. The results show that the number of peaks, the magnitudes of the insertion forces, and corresponding cone cracks decrease with increasing water content. Furthermore, we discussed the influence of water on cone crack fracture characteristics, cone angle, periodicity, crack speed and fracture energy release rate. These results provide a better understanding of the fracture processes of soft tissues with different water concentrations such as the lung, liver, and brain during needle insertion and the control of tissue damage during needle insertion involved in medical procedures.
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Affiliation(s)
- Muthukumar M
- Department of Mechanical Engineering, Indian Institute of Science, Bangalore, 560012, India.
- Marche Healthcare Pvt Ltd, Pondicherry, 605006, India
| | - M S Bobji
- Department of Mechanical Engineering, Indian Institute of Science, Bangalore, 560012, India.
| | - K R Y Simha
- Department of Mechanical Engineering, Indian Institute of Science, Bangalore, 560012, India.
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