Gate Electrodes Enable Tunable Nanofluidic Particle Traps

The ability to control the location of nanoscale objects
in liquids
is essential for fundamental and applied research from nanofluidics
to molecular biology. To overcome their random Brownian motion, the
electrostatic fluid trap creates local minima in potential energy
by shaping electrostatic interactions with a tailored wall topography.
However, this strategy is inherently static; once fabricated, the
potential wells cannot be modulated. Here, we propose and experimentally
demonstrate that such a trap can be controlled through a buried gate
electrode. We measure changes in the average escape times of nanoparticles
from the traps to quantify the induced modulations of 0.7 kBT in potential energy and
50 mV in surface potential. Finally, we summarize the mechanism
in a parameter-free predictive model, including surface chemistry
and electrostatic fringing, that reproduces the experimental results.
Our findings open a route toward real-time controllable nanoparticle
traps.

操控纳米尺度物体在液体中的位置能力对于纳米流体学至分子生物学等领域的基础研究和应用研究至关重要。为克服其随机的布朗运动，静电流体陷阱通过塑造与定制化壁面形貌的静电相互作用，在势能中形成局部极小值。然而，此策略本质上是静态的；一旦制造完成，势阱无法被调节。在此，我们提出并通过实验验证，此类陷阱可通过埋藏栅极电极进行控制。我们测量了纳米颗粒从陷阱中逸出的平均逃逸时间的变化，以量化诱导的势能0.7 kBT和表面电势50 mV的调制。最后，我们总结了该机制，构建了一个无参数的预测模型，该模型包括表面化学和静电边缘效应，能够再现实验结果。我们的发现为实时可控纳米颗粒陷阱开辟了途径。