Noise induced transport at microscale enabled by optical fields

Transport at the micro scale is an essential aspect for many emerging areas including manufacturing systems at the nanoscale. Transfer of beads decorated with cargo under the influence of optical fields provide an attractive means of such transport. Physical models that describe beads in optical fields under the influence of thermal noise are available which yield a qualitative understanding of the bead motion; however, it is difficult to arrive at models that provide quantitative agreement. The first contribution of the article is the determination of a model of a bead under a static field realized by optical forces where the model can be used to predict the motion of the bead under a time-varying optical potential with high fidelity. Close agreement between model based Monte Carlo simulations and experimental observations is seen. The other contribution is a strategy for directed transport of micron-sized particles that utilizes the proposed models to arrive at conclusions which are experimentally verified and easy to implement. The effectiveness of this transport mechanism is justified based on splitting probability computations. Applications to transport of cargo across multiple locations and transport of multiple cargo are experimentally demonstrated.