Cavitation in soft matter

Abstract

Cavitation is the sudden, unstable expansion of a void or bubble within a liquid or solid subjected to a negative hydrostatic stress. Cavitation rheology is a field emerging from the development of a suite of materials characterization, damage quantification, and therapeutic techniques that exploit the physical principles of cavitation. Cavitation rheology is inherently complex and broad in scope with wide-ranging applications in the biology, chemistry, materials, and mechanics communities. This perspective aims to drive collaboration among these communities and guide discussion by defining a common core of highpriority goals while highlighting emerging opportunities in the field of cavitation rheology. A brief overview of the mechanics and dynamics of cavitation in soft matter is presented. This overview is followed by a discussion of the overarching goals of cavitation rheology and an overview of common experimental techniques. The larger unmet needs and challenges of cavitation in soft matter are then presented alongside specific opportunities for researchers from different disciplines to contribute to the field. soft solids | traumatic brain injury | TBI | rheology | bubble Cavitation is the sudden, unstable expansion of a void or bubble within a liquid or solid subjected to a negative hydrostatic stress. While predominantly studied in fluids, cavitation is also an origin of damage in soft materials, including biological tissues. Examples of cavitation in fluids and soft solids are shown in Fig. 1 A-C. As one key example, strong evidence suggests that cavitation occurs in the brain during sudden impacts, leading to traumatic brain injury (TBI) (3). Research on this life-impacting injury and its relation to cavitation has accelerated in recent years (4-8). A broader and deeper understanding of cavitation within soft matter is necessary to navigate the complex paths that lead to damage in the brain and other soft materials. Cavitation in fluids has been studied extensively since Rayleigh's (9) formulation in 1917, which predicted that the maximum pressure in a cavitating liquid is proportional to the far-field pressure and inversely proportional to the cavity size. As surface energy

Growth of gas-filled penny-shaped cracks in decompressed hydrogels

“…30 who used the forced syringe injection of liquid and optical dye attenuation to measure the penny-shaped crack thickness. This new method also complements previous cavitation rheology methods, 33 based on the growth of spherical elastic (nonfracturing) bubbles to estimate material properties such as E. 34 Decompression sickness. Our key result also suggests a new potential mechanism for decompression sickness: the growth of inert gas pockets with a potentially catastrophic linear scaling, and a thin penny-shaped geometry that irreversibly fractures body tissues.…”

Laser cavitation rheology for measurement of elastic moduli and failure strain within hydrogels

“…LCR potentially offers new opportunities to investigate cellular mechanotransduction 47 , 67 in a 3D context with simultaneous characterization of the ECM mechanical properties. Moreover, through its ability to subject soft materials to large deformations at high strain rates, LCR may provide a unique tool to study and probe fundamental rheological properties of soft materials on the mesoscopic scale under such extreme conditions 58 . Moreover, LCR is particularly useful to study and probe the rheological response of biological systems to impact/blast injury with potential utility in laser microsurgery 59 , 60 , molecular delivery 61 , cell lysis 62 , tissue ablation 63 , and traumatic brain or spinal cord injury 64 – 66 .…”

Mechanical Characterization for Cellular Mechanobiology: Current Trends and Future Prospects

“…Cavitation rheology quantifies the elastic properties by growing a bubble in a gel or fluid and monitoring the pressure dynamics (Hashemnejad and Kundu, 2017). The resolution of cavitation rheology can go as low as 1 µm and requires only small sample volumes (Barney et al, 2020). One drawback of this method is that it is destructive to the sample.…”

“…One drawback of this method is that it is destructive to the sample. Questions also remain around relating gel fracture to cavitation and the influence of local network structures on cavitation bubble growth (Barney et al, 2020).…”