User:Yuanfeng/sandbox

topic: Nanoscale plasmonic motor

The Application
Because of its size and driven energy, the nanoscale plasmonic motor could provide rotational force at nanoscale, which would be widely used in energy conversion, biology and chemistry.The new developed light-driven nanoscale motor could address the limitations of earlier light mills. It generates comparable torque, which was made of gold and had much smaller size. At 100 nanometers across (one-tenth the size of other motors) it would make possible application like unwinding DNA in living cells and nanoelectromechanical systems(NEMS). .

When controlled winding and unwinding of DNA, the small motor could be illuminated at different wavelengths for in vivo manipulation. These motors could apply to solar light harvesting in nanoscopic systems through designing multiple motors to work at different resonance frequencies and single directions. Such multiple motor structures could be used to acquire torque from a broad wavelength range instead of a single frequency.

The limitation
The interaction increases between light and matter by the electrons oscillate collectively at the surface of metals, which is called "surface plasmons". An effect, which light fields are enhanced when they are resonant with these plasmons, has already been successfully used in techniques like single-molecule detection and surface-plasmon enhanced Raman spectroscopy (SERS). In the past, nanoparticles are rotated by exploiting the incident intrinsic movement of the light, but it is the first time that induce the rotation of a nanoparticle without exploiting the intrinsic angular momentum of light. The cost of materials used for motor is high, and the production process is complicate.

The future
to improve the efficiency of the light mills and scale them up for easier production.