A Digital Micro Magnetofluidic Platform For Lab on a Chip Applications

Abstract

This paper reports the design and investigation of a digital micro magnetofluidic platform for labonachip applications. The platform allows a ferrofluid droplet to be driven along a preprogrammed path. The platform consists of a programmable xypositioning stage, a permanent magnet and a glass plate coated with a thin layer of Teflon. First, the actuation of a standalone waterbased ferrofluid droplet was investigated. Circular, rectangular, triangular and numbereightshape trajectories were tested and analyzed. The speed of the droplet is evaluated from the position data of the black ferrofluid using a customized MATLAB program. The results show that better positioning accuracy and steady movement can be achieved with smooth trajectories. Next, the ferrofluid droplet as the driving engine for a cargo of other diamagnetic liquid droplets is demonstrated. The characteristics of different cargo volumes are investigated. Due to the liquid/liquid cohesion, a large cargo of five times the volume of a 3خ¼L ferrofluid droplet can be transported. If the cargo is larger than the driving ferrofluid droplet, the liquid system forms a long trail that faithfully follows the preprogrammed path. Various mixing experiments were carried out. The effectiveness of mixing in this system is demonstrated with a titration test as well as a chemiluminescence assay. The platform shows a robust, simple and flexible concept for implementing a complex analysis protocol with multiple reaction steps.