Instabilities as a measurement tool for soft materials

Mechanical instabilities such as wrinkles, creases, and folds have long been viewed as a source of frustration for engineers and often a point of curiosity among scientists. Scientists aspire to understand the underlying physics behind the formation of mechanical instabilities and how to manipulate them for various endeavours, while engineers use this same understanding to design materials that inhibit or impede the formation of instabilities in critical applications. In recent years, a new movement in this community has emerged: harnessing these instabilities to provide critical insight into the properties of soft materials. We describe here the foundation of one particular analytical tool based on surface wrinkling and how this approach has been used to measure materials and systems that are inherently difficult to characterize. We also highlight some of the specific challenges and opportunities we envision for this measurement tool. Within this framework, we believe that there is great potential for broadening the capabilities of wrinkling metrology as the field of instability-engineering continues to mature.