This CAREER award supports theoretical and computational research and education to advance understanding of mechanics how mechanical devices work at microscopic length scales down to the scale of nanostructures. Nature's fascinating ability to make nanomachines that can sense and respond to their environment has motivated researchers to explore different ways of miniaturizing functional devices. One of the strategies that was successfully employed is to make patterned /composite atomic layers, which can be prepared in a flat state and can subsequently transform their shapes in response to external stimuli. By using ideas from the folding of paper origami, researchers have produced functional self-folding origami micro-devices, which can perform biopsies and deliver drugs. Similarly, the ideas from paper kirigami and pop-up cards have led researchers to design micro-scale stretchable electronics and extremely sensitive force sensors. Functional micro-rockets have been employed for manipulation and isolation of cells and for diverse environmental applications, including water monitoring, remediation and detoxification.
As devices are made smaller and smaller, their mechanics will become increasingly sensitive to imperfections and random fluctuations coming from the environment. For example, random imperfections transform flat atomic layers into shapes reminiscent of crumpled paper, while random thermal agitations can spontaneously crush spherical shells above some critical temperature. These effects can defy intuition based on the mechanics of macroscopic structures. This makes it challenging to design functional micro- and nano-structures. The PI aims to develop a theoretical and computational framework to investigate the mechanics of complex microscopic slender structures in the presence of defects and random fluctuations. The research will illuminate how biological structures function, to design novel electronic structures that can be tuned mechanically, and the design of microscopic structures that are prepared in a flat state and can subsequently self-fold to desired shapes with potential for biomedical devices and diverse environmental and industrial applications.
The research proposed here will help educate the next generation of interdisciplinary scientists whose expertise resides at the intersection of continuum mechanics, statistical mechanics, and biology. Moreover, courses in continuum mechanics are typically taught from an engineering perspective and are very rarely attended by students with interests in biology and statistical mechanics. To address this issue, the PI has developed a new graduate course titled "Lessons from Biology for Engineering Tiny Devices" and will add new topics to the required sophomore engineering course on continuum mechanics. This award also supports educating, inspiring and mentoring high school students from underrepresented and socioeconomically disadvantaged populations in Trenton, NJ. The public will be reached with a new educational blog that will cover topics at the interface of biology, physics, mechanics and engineering.
This CAREER award supports a theoretical and computational study integrated with education of how thermal fluctuations, nonequilibrium fluctuations, and disorder affect the mechanics of microscopic slender structures. The research agenda is motivated by the importance of biological microscopic shells and by recent experimental developments, where atomically thin layers of materials of various shapes and compositions are now routinely produced. Experimentalists can make highly stretchable graphene kirigami devices and composite/patterned atomic layers which can transform their shapes in response to external stimuli. However,, theory cannot describe the mechanics of thermalized or disordered flat sheets beyond their linear response to external forces. Less is known about the statistical mechanics of shells. The goal of this project is to bridge the gap between theory and experiments.
This project will develop a theoretical framework and simulation tools that will enable studies of the mechanics of structures with complex geometries in the presence of thermal fluctuations, nonequilibrium fluctuations, and quenched defects. The basis for the development of coarse-grained finite-element molecular dynamics simulations, will be studies of small elements of three different types: flat sheets, curved shells and frustrated sheets. The effective static and dynamic stress-strain responses for such patches due to combination of loading, such as bending, stretching, shearing, in the presence of fluctuations will be studied by developing new renormalization group calculations, with defects treated using the replica approach. The PI will seek quantitative differences between the role of defects and of thermal and nonequilibrium fluctuations, which could be reflected in different universal exponents in the nonlinear regime of static stress-strain curves, as well as in different rate-dependent responses to dynamic loads. Mechanical properties are expected to depend critically on geometry, and three different types of patches - flat sheets, curved shells, and frustrated sheets - are expected to exhibit qualitatively different behaviors, for example fluctuations can stabilize flat sheets, but they reduce the stability of shells. Based on these studies the PI will develop coarse-grained simulation tools that will enable studies of the statistical mechanics of structures with complex geometries. The award will have direct implication for the mechanics of biological structures, for the design of novel electronic structures that can be tuned mechanically, and for the design of microscopic structures that are prepared in a flat state and can subsequently self-fold to desired shapes with potential for biomedical devices and diverse environmental and industrial applications.
The research proposed here will help educate the next generation of interdisciplinary scientists whose expertise resides at the intersection of continuum mechanics, statistical mechanics, and biology. Moreover, courses in continuum mechanics are typically taught from an engineering perspective and are very rarely attended by students with interests in biology and statistical mechanics. To address this issue, the PI has developed a new graduate course titled "Lessons from Biology for Engineering Tiny Devices" and will add new topics to the required sophomore engineering course on continuum mechanics. This award also supports educating, inspiring and mentoring high school students from underrepresented and socioeconomically disadvantaged populations in Trenton, NJ. The public will be reached with a new educational blog that will cover topics at the interface of biology, physics, mechanics and engineering.
