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Abstract Soft materials play an integral part in many aspects of modern life including autonomy, sustainability, and human health, and their accurate modeling is critical to understand their unique properties and functions. Today’s finite element analysis packages come with a set of pre-programmed material models, which may exhibit restricted validity in capturing the intricate mechanical behavior of these materials. Regrettably, incorporating a modified or novel material model in a finite element analysis package requires non-trivial in-depth knowledge of tensor algebra, continuum mechanics, and computer programming, making it a complex task that is prone to human error. Here we design a universal material subroutine, which automates the integration of novel constitutive models of varying complexity in non-linear finite element packages, with no additional analytical derivations and algorithmic implementations. We demonstrate the versatility of our approach to seamlessly integrate innovative constitutive models from the material point to the structural level through a variety of soft matter case studies: a frontal impact to the brain; reconstructive surgery of the scalp; diastolic loading of arteries and the human heart; and the dynamic closing of the tricuspid valve. Our universal material subroutine empowers all users, not solely experts, to conduct reliable engineering analysis of soft matter systems. We envision that this framework will become an indispensable instrument for continued innovation and discovery within the soft matter community at large. 

Abstract Tissue mimicking materials are designed to represent real tissue in applications such as medical device testing and surgical training. Thanks to progress in 3D‐printing technology, tissue mimics can now be easily cast into arbitrary geometries and manufactured with adjustable material properties to mimic a wide variety of tissue types. However, it is unclear how well 3D‐printable mimics represent real tissues and their mechanics. The objective of this work is to fill this knowledge gap using the Stratasys Digital Anatomy 3D‐Printer as an example. To this end, we created mimics of biological tissues we previously tested in our laboratory: blood clots, myocardium, and tricuspid valve leaflets. We printed each tissue mimic to have the identical geometry to its biological counterpart and tested the samples using identical protocols. In our evaluation, we focused on the stiffness of the tissues and their fracture toughness in the case of blood clots. We found that the mechanical behavior of the tissue mimics often differed substantially from the biological tissues they aim to represent. Qualitatively, tissue mimics failed to replicate the traditional strain‐stiffening behavior of soft tissues. Quantitatively, tissue mimics were stiffer than their biological counterparts, especially at small strains, in some cases by orders of magnitude. In those materials in which we tested toughness, we found that tissue mimicking materials were also much tougher than their biological counterparts. Thus, our work highlights limitations of at least one 3D‐printing technology in its ability to mimic the mechanical properties of biological tissues. Therefore, care should be taken when using this technology, especially where tissue mimicking materials are expected to represent soft tissue properties quantitatively. Whether other technologies fare better remains to be seen. 

Abstract Thromboembolic diseases are a significant cause of mortality and are clinically treated enzymatically with tissue plasminogen activator (tPA). Interestingly, prior studies in fibrin fibers and fibrin gels have demonstrated that thrombolysis may be mechanically sensitive. This study aims to expand mechano‐lytic studies to whole blood clots. Furthermore, this study investigates not only how mechanics impacts lysis but also how lysis impacts mechanics. Therefore, clots made from whole human blood are exposed to tPA while the clots are either stretched or unstretched. After, the resulting degree of clot lysis is measured by weighing the clots and by measuring the concentration of D‐dimer in the surrounding bath. Additionally, each clot's mechanical properties are measured. This study finds that mechanical stretch accelerates loss in clot weight but does not impact the lysis rate as measured by D‐dimer. Moreover, lysis not only removes clot volume but also reduces the remaining clot's stiffness and toughness. In summary, tPA‐induced lysis of whole clot appears mechanically insensitive, but stretch reduces clot weight. Furthermore, results show that thrombolysis weakens clot. This suggests that thrombolysis may increase the risk of secondary embolizations but may also ease clot removal during thrombectomy, for example.