# Joule Heating-Induced Particle Manipulation on a Microfluidic Chip

## TL;DR

This paper introduces an energy-efficient electrokinetic method using Joule heating to manipulate and cluster colloidal particles on a microfluidic chip, avoiding complex laser systems.

## Contribution

It presents a novel on-chip particle manipulation technique leveraging Joule heating-induced electrothermal flows, enabling pattern formation with low power.

## Key findings

- Effective particle concentration into patterns achieved
- Low power consumption demonstrated
- Potential applications in biological cell manipulation

## Abstract

We develop an electrokinetic technique that continuously manipulates colloidal particles to concentrate into patterned particulate groups in an energy efficient way, by exclusive harnessing of the intrinsic Joule heating effects. Our technique exploits the alternating current electrothermal flow phenomenon which is generated due to the interaction between non-uniform electric and thermal fields. Highly non-uniform electric field generates sharp temperature gradients by generating spatially-varying Joule heat that varies along radial direction from a concentrated point hotspot. Sharp temperature gradients induce local variation in electric properties which, in turn, generate strong electrothermal vortex. The imposed fluid flow brings the colloidal particles at the centre of the hotspot and enables particle aggregation. Further, manoeuvering structures of the Joule heating spots, different patterns of particle clustering may be formed in a low power budget, thus, opening up a new realm of on-chip particle manipulation process without necessitating highly focused laser beam which is much complicated and demands higher power budget. This technique can find its use in Lab-on-a-chip devices to manipulate particle groups, including biological cells.

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Source: https://tomesphere.com/paper/1904.07315