Soft matter physics: the study of soft, squishy, and deformable objects. Examples of soft matter are all around us. Most parts of our body (e.g. skin, tendon, blood) and many engineered materials (e.g. plastics, rubbers, foams, gels) fall under the category of soft matter. More precisely, the field of Soft Matter Physics encompasses systems where room temperature thermal energy is comparable to that of applied mechanical or thermal stresses. Soft Matter often includes structure on mesoscopic size scales (sizes anywhere from roughly 10 nm up to about 100 um; between that of a single atom but smaller than we can easily see with the naked eye).
The Physics of Soft Matter Lab (PoSMLab) at Harvey Mudd College is broadly interested in the physical principles that govern the behavior of soft materials. Our recent work has been focused on understanding the physical principles of latch-mediated spring actuated (LaMSA) systems, in which springs primarily drive motion. An archer's bow and arrow provides a great example of how a LaMSA system works: first a motor (the archer's muscles) loads elastic energy into a spring-like element (the bow), which is held in place by a latch (the archer's fingers). Upon releasing the latch, the stored elastic energy is rapidly converted into kinetic energy of motion.
Some organisms have this combination of a loading motor, spring, and latch built into their anatomy, and can use it to perform ultra-fast movement. Mantis shrimp use elastic energy to drive their hammer-like appendages at speeds greater than 60 mph and use this fast-moving hammer to break open snail and crab shells. What's perhaps even more impressive is that the performance of some of these biological LaMSA systems exceeds that of current engineering capabilities for repeatable kinematic performance at small sizes.
By understanding the physical principles that govern these systems, our aim is to contribute to a better understanding of the evolutionary dynamics of these organisms and inform future engineering design.
In the next few years PoSMLab is focused primarily on two guiding questions:
1) What properties determine the maximum kinematic performance of elastic materials?
2) What principles govern the mechanics of biological LaMSA systems?