Abstract: A technique to guide a micro- or nano-scale particle uses the wavelengths of light beams to control the direction of motion of the particle. In this technique, an optical asymmetry is introduced into the particle to form a composite particle. The composite particle includes two faces that preferentially absorb light of different wavelengths, independent of the particle orientation. The difference in absorption spectra of the two faces creates a bidirectional and local thermal gradient that is externally switchable by changing the wavelength of the incident light beams. This thermal gradient induces a thermophoretic drift that moves the composite particle. A two-faced nanoparticle can be guided using the optically induced thermophoretic drift as the propulsion mechanism.

Abstract: A technique to guide a micro- or nano-scale particle uses the wavelengths of light beams to control the direction of motion of the particle. In this technique, an optical asymmetry is introduced into the particle to form a composite particle. The composite particle includes two faces that preferentially absorb light of different wavelengths, independent of the particle orientation. The difference in absorption spectra of the two faces creates a bidirectional and local thermal gradient that is externally switchable by changing the wavelength of the incident light beams. This thermal gradient induces a thermophoretic drift that moves the composite particle. A two-faced nanoparticle can be guided using the optically induced thermophoretic drift as the propulsion mechanism.