Alternatives to Dark Energy

Perhaps the deepest mystery in physics today is the origin of the accelerating expansion of the universe.  Professors Khoury and Trodden work, among other things, on the possibility that it is due to a dark sector with new light degrees of freedom.  Screening mechanisms, such as chameleon and symmetron, may explain why such scalars, if light, have escaped detection.


Bio-optics and bio-optical materials

Prof. Alison Sweeney and her colleagues believe that the reflective structures in giant clams help them grow algae. The clams use sub-wavelength structures formed from a protein called reflectin to optimize the photosynthesis of the algae living in the clam tissues.

Air-fluidized grains

Spatiotemporal heterogenous dynamics in air-fluidized grains near jamming. The colors represent the average speed over a time interval large enough for grain-sized rms displacement. The most mobile grains are in red, the least are in blue, across the rainbow. Note the stringy correlations of the mobile grains in red. From the lab of Prof. Doug Durian.

DNA-Functionalized Carbon Nanotube Chemical Sensors

The group of Professor Charlie Johnson has developed chemical sensors using single-walled carbon nanotubes wrapped with single-stranded DNA adsorbed to the nanotube's outer wall.

Nanoscale Electronic Nose

Prof. Charlie Johnson's group at Penn have coupled olfactory receptor proteins from mice to carbon nanotubes to create a prototype electronic nose. Olfactory receptors are embedded in nanodiscs that mimic the environment of the olfactory cell membrane.  Odorant molecules bind to the receptor, which produces an electrical response in the carbon nanotube (gray cylinder).