Three-dimensional electrokinetic tweezing: device design, modeling, and control algorithms

Abstract

We show how to extend electrokinetic tweezing (which can manipulate any visible particles and has more favorable force scaling than optical actuation enabling manipulation of nanoscale objects to nanoscopic precision) from two-dimensional control to the third dimension (3D). A novel and practical multi-layer device is presented that can create both planar and vertical flow and electric field modes. Feedback control algorithms are developed and demonstrated in realistic simulations to show 3D manipulation of one and two particles independently. The design and control results presented here are the essential next step to go from current 2D manipulation capabilities to an experimental demonstration of nano-precise 3D electrokinetic tweezing in a microfluidic system. Doing so requires integration with vision-based nano-precise 3D particle imaging, a capability that has been shown in the literature and which we are now combining with the 3D actuation and control methods demonstrated here.

A Trajectory Planning Model for the Manipulation of Particles in Microfluidics

“…al., [1] and [2], some examples can be found of the use of control techniques. A generalization for the manipulation of particles in the three-dimensional case also exists in the study of Probst and Shapiro [10].…”

“…The resulting trajectory γ * can eventually be smoothed out before passing it to the manipulation algorithm. The combination of the proposed method with the manipulation techniques of Shapiro and coworkers ([4], [1], [2] and [10]) would allow for an integrated system of detection, planned manipulation and control of particles towards an arbitrary target.…”

Three-dimensional anti-Brownian electrokinetic trapping of a single nanoparticle in solution

“…In recognition of the need for 3D electrokinetic trapping, arrangements of two stacked sets of four planar electrodes 15 or multiple crossed microchannels 16 have been suggested as means of providing 3D control. However, finite-volume time-domain numerical modeling has predicted that a simpler configuration of just four electrodes in a tetrahedral arrangement should suffice to form an electric field of controllable orientation and strength.…”

“…The double peak in z, which varies between device realignments, is most likely an effect of coupled motion exacerbated by non-ideal alignment and non-optimized response parameters and will require further analysis of the electric field to address. 16 The data clearly show that the nanoparticle is trapped in 3D exceeding one minute. Figure 4 shows a single ROI image from the video stream used for Figure 3.…”

Nanoscale Imaging with a Single Quantum Dot

“…The demonstrated approach provides a direct measurement of the electromagnetic field profile, and also enables deterministic control of these interactions by precise placement of the QD at different field locations. Fluidbased methods for three-dimensional tracking and control25 of particles could also be incorporated to perform three-dimensional imaging with nanoscale accuracy. In addition, by combining this technique with methods for selective immobilization of QDs13 , our results can be extended from probing to a deterministic assembly of active quantum emitters and plasmonic structures for development of new nanoelectronic devices26 and quantum optical circuits27 .METHODSFluid composition.…”