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.

操控液体中纳米级物体位置的能力，对于纳米流体学至分子生物学等基础与应用研究至关重要。为克服其随机的布朗运动，静电流体陷阱通过精心设计的壁面形貌塑造静电相互作用，从而在势能中形成局部极小值。然而，此策略本质上具有静态性；一旦制造完成，势阱便无法进行调节。本研究中，我们提出并通过实验验证了，此类陷阱可通过埋入式栅极电极进行控制。我们测量了纳米粒子从陷阱中逃逸的平均时间变化，以量化势能中0.7 kBT和表面电势中50 mV的诱导调制。最终，我们基于表面化学和静电边缘效应的无参数预测模型，总结了该机制，该模型能够再现实验结果。我们的发现为实时可控纳米粒子陷阱开辟了新的途径。