It’s doubtful whether the little creatures that inhabit seashells can fully appreciate the amazing structures in which they live. But engineers and materials scientists certainly do. Seashells are incredibly hard and strong, yet amazingly lightweight. Materials scientists would dearly love to have the cosmic recipe for making this kind of material, along with blueprints for other nifty things like tooth enamel, cartilage, and muscle. Materials like this could be used in countless ways; the market possibilities are huge. The fact that it took billions of years for these things to evolve doesn’t faze engineers—they hope to be able to come up with workable copies in a matter of decades.

Professor K.T. Ramesh and Associate Dean Andrew Douglas form the faculty core of JHU’s Laboratory for Active Materials and Biomimetics (LAMB), JHU’s contribution to this effort. They characterize the mechanical and electromechanical properties of natural materials as well as active materials that are supposed to mimic nature. They also generate active materials though tissue engineering.

Prof. Ramesh explains that there are two basic approaches to biomimetics: in the first, the researcher takes a material concept from nature, like the material of a seashell or the fibrous muscles of the heart, and uses that concept in an artificial system. The second approach looks at the functional concept in nature, in an attempt to isolate the mechanisms responsible for the unique way a certain material works. To understand muscle material, for example, researchers look at how muscle fibers undergo a complicated dance of contracting and swelling in preferred directions through the diffusion of calcium. Because muscle itself is highly variable from one person to the next and from one part of the body to another, this involves huge numbers of experiments on muscle tissue and extensive data mining. The functional approach preferred by Profs. Ramesh and Douglas instead centers around an artificial analogy based on the mechanism occurring in muscle tissue. They build a mathematical model that mimics the mathematics of the natural phenomena they wish to understand, and then work their way backwards through various artificial models until they are at a point where they can consider the actual biological processes taking place.

Prof. Douglas collaborates with Professor Bill Hunter and his former PhD student John Criscione of JHU’s Biomedical Engineering Department, using experimental materials to refine their mathematical models of muscle function. The mathematical description first isolates important mechanical concepts such as strain, activation, and time dependency. How much internal force (or stress) causes muscle fibers to move, and how does their movement evolve over time? Like rubber bands, muscle fibers elongate, and strain is a measure of their elongation per unit length. But while rubber bands double their length or more when pulled, muscle fibers only elongate up to about 25% and can also contract when activated. While muscles are activated by the concentration of calcium ions, the artificial materials used in the LAMB lab are complex polymers that respond to a change in pH of the environment. They have been able to mimic the deformation characteristics of smooth muscle fibers isotropically, that is, swelling and contracting with strains between 2% and 25%, in all directions evenly. The next step, according to Douglas, is to make the material work in a preferred direction, as muscle tissue does.

[Welcome & Overview] [People] [Research] [Seminars, Events & Positions] [Undergraduate Programs] [Graduate Programs] [Student Groups] [Campus Life] [Home]