High-Throughput Mechanical Characterization of Ultra-Soft Biological Materials Using Puncture and Needle-Induced Cavitation

Mechanical properties play a critical role in regulating cell behavior, tissue development, and disease progression. The moduli of many ultra-soft biological materials (E<100kPa), like the extracellular matrix (ECM), directly influence cell metabolism and differentiation. Despite the demand for new materials that utilize mechanical properties to control cellular behavior, there has been limited progress in developing high-throughput, standardized methods for measuring these properties. Traditional mechanical characterization techniques are often ill-suited for biological materials due to their brittleness, softness, and limited quantities. To address these challenges, our group is developing a novel method that enables rapid sample testing using puncture and needle-induced cavitation (NIC) to characterize cell culture gels in 96-well plates. In puncture, a needle is inserted and removed from the sample, while NIC involves inserting a needle and applying pressure at the tip to form and expand a cavity within the material. The material's response to these tests yields insights into its elastic and fracture properties. Here, we discuss our new understanding of how needle size relates to the complex strain states in soft gels confined within the well-plate geometry and how these relationships can be rapidly analyzed to maximize efficiency in characterizing the gels' mechanical properties.