Related Experiment Video
Updated: Dec 4, 2025
08:41
Generation and Control of Electrohydrodynamic Flows in Aqueous Electrolyte Solutions
Published on: September 7, 2018
9.3K
Regulating the aggregation of colloidal particles in an electro-osmotic micropump
Zhu Zhang1, Joost de Graaf, Sanli Faez
1Nanophotonics, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, The Netherlands. z.zhang@uu.nl.
Soft Matter
|October 23, 2020
Summary
Electro-osmotic aggregation of colloidal particles in microfluidic channels can cause clogging. Reversing electric potential or using a tuned square-waveform potential can control particle flow and prevent clogging.
Area of Science:
- Microfluidics
- Colloidal science
- Electrokinetics
Background:
- Microfluidic channels are crucial for lab-on-a-chip devices.
- Unrestricted particle transport is essential for many microfluidic applications.
- Particle aggregation can lead to microfluidic channel clogging.
Purpose of the Study:
- To investigate electro-osmotic aggregation of colloidal particles at microchannel openings.
- To understand the influence of electric fields and salt gradients on particle transport.
- To develop strategies for controlled particle transport and anti-fouling in microfluidics.
Main Methods:
- Video microscopy to observe particle aggregation.
- Numerical modeling using Stokes-Poisson-Nernst-Planck equations.
- Experimental manipulation of electric potential (DC reversal and square-waveform).
Main Results:
- Identified transport processes driven by electric fields and salt gradients.
- Demonstrated that a balance of these forces leads to particle aggregation and channel clogging.
- Showed that a tuned square-waveform electric potential can achieve net colloid flow through the channel.
Conclusions:
- Controlled particle transport in microfluidic channels is achievable.
- Understanding electro-osmotic aggregation is key for designing microfluidic pumps.
- Results offer insights for anti-fouling strategies in ultra-filtration systems.
Related Concept Videos
01:09Colloidal precipitates
3.5K
The high insolubility of some precipitates can result in an unfavorable relative supersaturation. This can lead to colloidal particles with a large surface-to-mass ratio, where adsorption is promoted. For instance, in the precipitation of silver chloride, silver ions are adsorbed on the surface of the colloidal particles, forming a primary layer. This layer attracts ions of opposite charge (such as nitrate ions), forming a diffuse secondary layer of adsorbed ions. This electric double layer...
3.5K
01:06Coagulation
871
Colloidal solids are solid particles suspended in solution. They are usually negatively charged, attracting a compact primary layer of positively charged ions, which attract more counterions to form an electrical double layer. Electrostatic repulsion between the charged double layers prevents the particles from colliding, stabilizing the colloids. These solids are often undesirable because they can contain toxins that are difficult to remove. Coagulation is a technique that helps aggregate and...
871
03:22Colloids
19.9K
Children at play often make suspensions such as mixtures of mud and water, flour and water, or a suspension of solid pigments in water known as tempera paint. These suspensions are heterogeneous mixtures composed of relatively large particles that are visible to the naked eye or can be seen with a magnifying glass. They are cloudy, and the suspended particles settle out after mixing. On the other hand, a solution is a homogeneous mixture in which no settling occurs and in which the dissolved...
19.9K