Exploring the Diverse World of Biofluid Mechanics
Biofluid mechanics is a fascinating field of study that deals with the mechanics of fluids in or around biological organisms. It encompasses a broad range of subfields, including red blood cells, biotribology, comparative biomechanics, computational biomechanics, experimental biomechanics, continuum biomechanics, plant biomechanics, sports biomechanics, and vascular biomechanics. In this article, we will take a closer look at each of these subfields.
Red blood cells are essential components of our cardiovascular system. In vivo, whole blood is assumed to be an incompressible Newtonian fluid. However, when considering forward flow within arterioles, this assumption fails. At the microscopic scale, the effects of individual red blood cells become significant, and whole blood can no longer be modeled as a continuum. When the diameter of the blood vessel is just slightly larger than the diameter of the red blood cell, the Fahraeus–Lindquist effect occurs, and there is a decrease in wall shear stress. However, as the diameter of the blood vessel decreases further, the red blood cells have to squeeze through the vessel and often can only pass in a single file. In this case, the inverse Fahraeus–Lindquist effect occurs, and the wall shear stress increases. The study of red blood cells is an exciting area of research that can lead to a better understanding of cardiovascular diseases and the development of new treatments.
Biotribology is the study of friction, wear, and lubrication of biological systems, particularly human joints such as hips and knees. In general, these processes are studied in the context of contact mechanics and tribology. One of the additional aspects of biotribology is the analysis of subsurface damage resulting from two surfaces coming in contact during motion, such as rubbing against each other, as in the evaluation of tissue-engineered cartilage. Biotribology is essential in understanding joint diseases and injuries and in developing new treatments and prosthetic implants.
Comparative biomechanics is the application of biomechanics to non-human organisms, whether used to gain greater insights into humans or into the functions, ecology, and adaptations of the organisms themselves. Common areas of investigation are animal locomotion and feeding, as these have strong connections to the organism’s fitness and impose high mechanical demands. Comparative biomechanics overlaps strongly with many other fields, including ecology, neurobiology, developmental biology, ethology, and paleontology. It is often applied in medicine, as well as in biomimetics, which looks to nature for solutions to engineering problems.
Computational biomechanics is the application of engineering computational tools, such as the finite element method, to study the mechanics of biological systems. Computational models and simulations are used to predict the relationship between parameters that are otherwise challenging to test experimentally or used to design more relevant experiments, reducing the time and costs of experiments. Computational biomechanics is an essential ingredient in surgical simulation, which is used for surgical planning, assistance, and training. It is an exciting area of research that has the potential to revolutionize medical simulations and improve surgical outcomes.
Experimental biomechanics is the application of experiments and measurements in biomechanics. It is an important subfield that allows researchers to validate computational models and simulations and to gather data that cannot be obtained through other methods.
Continuum biomechanics is the mechanical analysis of biomaterials and biofluids using the concepts of continuum mechanics. This assumption breaks down when the length scales of interest approach the order of the micro structural details of the material. One of the most remarkable characteristics of biomaterials is their hierarchical structure. In other words, the mechanical characteristics of these materials rely on physical phenomena occurring at multiple levels, from the molecular all the way up to the tissue and organ levels. Biomaterials are classified into two groups, hard and soft tissues. The mechanical deformation of hard tissues (such as wood, shell, and bone) may be analyzed with the theory of linear elasticity. On the other hand, soft tissues (such as skin, tendon, muscle, and cartilage) usually undergo large deformations, and their analysis relies on the finite strain theory and computer simulations. The interest in continuum biomechanics is spurred by the need for realism in the development of medical simulation.
Plant biomechanics is the application of biomechanical principles to plants, plant organs, and cells. The application of biomechanics for plants ranges from studying the resilience of crops to environmental stress to development and morphogenesis at the cell and tissue scale, overlapping with mechanobiology. Plant biomechanics is an exciting field of research that can help us better understand the growth and development of plants and lead to the development of new technologies in agriculture.
Sports biomechanics applies the laws of mechanics to human movement to gain a greater understanding of athletic performance and to reduce sports injuries. It focuses on the application of the scientific principles of mechanical physics to understand the movements of action of human bodies and sports implements such as cricket bats, hockey sticks, and javelins. Elements of mechanical engineering, electrical engineering, computer science, gait analysis, and clinical neurophysiology are commonly used methods in sports biomechanics. Proper understanding of biomechanics relating to sports skill has the greatest implications on sports performance, rehabilitation, and injury prevention, along with sports mastery.
Finally, vascular biomechanics focuses on the description of the mechanical behavior of vascular tissues. Cardiovascular disease is the leading cause of death worldwide, and studying the mechanical properties of these complex tissues improves the possibility of better understanding cardiovascular diseases and drastically improving personalized medicine. Vascular tissues are inhomogeneous with a strongly nonlinear behavior. Generally, this study involves complex geometry with intricate load conditions and material properties. The correct description of these mechanisms is based on the study of physiology and biological interaction. Therefore, it is necessary to study wall mechanics and hemodynamics with their interaction. It is also necessary to premise that the vascular wall is a dynamic structure in continuous evolution. This evolution directly follows the chemical and mechanical environment in which the tissues are immersed, such as wall shear stress or biochemical signaling.
In conclusion, biofluid mechanics is a fascinating and diverse field of study with applications in various disciplines, from medicine to engineering, to agriculture. It has the potential to revolutionize medical simulations, improve surgical outcomes, and lead to the development of new treatments and technologies. As we continue to learn more about the mechanics of biological systems, we will undoubtedly discover new ways to improve the quality of life for humans and other organisms.
