Support: Primary/Partial NSF MRSEC DMR-11-20901

1. A color changing stress-sensorArjun G. Yodh, University of Pennsylvania, DMR 1120901 Composites are a means of designing the material properties of an assembly through collective interactions. Here we show that we can make a color-changing stress sensor within the membrane of of a synthetic capsule. Porphyrin molecules – macromolecules that emit light depending on their configuration – are embedded in the membrane of a synthetic capsule made of polymer. When the membrane is stressed in a glass tube under regulated pressure, the stretching of the membrane induces a conformational change in the porphyrin and a change in the color it emits. By directly relating the membrane stress to to the color, we can calibrate the stress sensor. The linear correlation between stress and change in wavelength of light means that an optical detector can be used to measure stress. Neha P. Kamat, Zhengzheng Liao, Laurel E. Moses, Jeff Rawson, Michael J. Therien, Ivan J. Dmochowski, and Daniel A. Hammer, Proceedings of the National Academy of Sciences USA, 2011 Support: Primary/Partial NSF MRSEC DMR-11-20901