3-Dimensional electrokinetic tweezing for micro and nano assembly

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

“…Here we present a device design, along with the associated modeling and control, which can extend EK trapping and steering capabilities to the third dimension. The modeling, algorithm, and simulation results we present here are a prerequisite to subsequent experimental demonstrations, as has been the case for all our prior theory developments [22][23][24][25][26] that subsequently led to experimental demonstrations for control of one and multiple cells [4,18], swimming bacteria [18], and EK tweezing of single quantum dots to tens of nanometers precision [5,27].…”

“…DEP actuation has been used to trap [12][13][14], sort [15,16], and move particles by sequentially trapping them in adjacent traps [17]. EK tweezing allows control of essentially any visible objects [4,5,18]. It has enabled on-chip individual manipulation of one and multiple cells [4], including the steering and trapping of live swimming cells [18].…”

“…EK tweezing allows control of essentially any visible objects [4,5,18]. It has enabled on-chip individual manipulation of one and multiple cells [4], including the steering and trapping of live swimming cells [18]. The favorable scaling of electroosmotic (EO) actuation (drag forces scale with particle size [19] rather than with particle volume as do optical and DEP forces [20]) has further allowed control of nanoscopic particles to tens of nanometers precision [5,21], the best reported precision to date of any method.…”

“…The process repeats continuously to steer the particle along its desired path. Device fabrication, vision sensing, and control design for implementing such a system is covered in detail in [4,18]; the latter reference includes both a detailed protocol as well as sensing and control software to realize the feedback manipulation.…”

“…We first briefly summarize how EK tweezers work in two spatial dimensions [4,18,23] before showing how to extend the method to work in the third dimension. As shown in figure 1, a micro-fluidic device, a vision system (microscope, camera, and particle detection software), and a control algorithm are connected in a feedback loop.…”