Thermophoretic Manipulation of Micro- and Nanoparticle Flow through a Sudden Contraction in a Microchannel with Near-Infrared Laser Irradiation

Micro- and nanochannels are promising for state-of-the-art sensing technologies in biomedical devices, but the accurate and selective control of nanomaterials near the sensing elements is a challenge. This paper rises to the challenge by introducing an unconventional manipulation technique, combining laser-induced thermophoresis with a sudden narrowing of the channel. The strength of thermophoresis, compared to other transport mechanisms, lies in its selectivity: Targets can be guided to the sudden contraction, while unwanted particles are repelled. Also, the nearby flow field leads to dynamical concentration of target materials.