Gate Electrodes Enable Tunable Nanofluidic Particle Traps

TL;DR

This paper demonstrates a novel method to actively control nanofluidic particle traps using gate electrodes, enabling real-time modulation of nanoparticle confinement in liquids.

Contribution

The authors introduce a buried gate electrode to dynamically tune electrostatic traps, overcoming the static limitations of traditional nanofluidic trapping methods.

Findings

Measured potential energy modulation of 0.7k_B T

Observed surface potential change of 50 mV

Developed a predictive model matching experimental data

Abstract

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 fluidic 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 $0.7k_\rm{B}T$ 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 towards real-time controllable nanoparticle traps.