BIOPARTICLE SEPARATION AND MANIPULATION USING DIELECTROPHORESIS Advisor: Yi-Chu Hsu Student: Le Van Cong ( 黎 文 功 ) Date: 11/04/2011

Outline 1.Introduction 2.Working principle and design 3.Fabrication and experimental setup 4.Results and discussion 5.Conclusion 6.References

Introduction The non-uniform AC electric field with the induced dipole in the particle. This paper presents a DEP-based microfluidic system with applications in micro-sized particle manipulation and separation.

Working principle and design Particles under positive DEP were attracted to the edges of the electrodes. Particles under negative DEP were repelled away from the electrodes and levitated at certain height above the electrodes.

Working principle and design Direction of cell movement depending on DEP response: (a) positive DEP cells and (b) negative DEP cells. the more polarisable particlethe less polarisable particle

Working principle and design The solution of the problem close to the electrode. (a) The calculated electric potential and (b) electric field E

Working principle and design The solution of the problem close to the electrode. (c) Logarithmical magnitude of the field-square gradient, (d) Directions of DEP. Different scales are used in getting the non-dimensional values

Working principle and design Electrodes: The width and the spacing between electrodes is : 30 μm 30 μm Cr/Au Base Si3N4

Working principle and design Schematic diagram of the DEP device (cross section) ElectrodesBase PCB Glass / Silicon Suspension medium Fluid inletFluid outlet

Fabrication and experimental setup The fluidic channel, which is 3000 μm wide, 10 4 μm long and 100 μm deep resulting in a volume of ∼ 3 μl. Fluidic access holes of ∼ 1 mm. Electrodes

Fabrication and experimental setup The electric field was generated by applying a sinusoidal voltage (1 kHz–15 MHz) up to 10 V with a function generator HP Agilent 33210A. Polystyrene particles (cross-linked with 4% to 8% divinylbenzene, DVB) of diameter of 4.3 μm.

Fabrication and experimental setup An inspection microscope system Olympus MX40 mounted with CCD and Video camera.

Results With the applied voltage off latex beads were introduced into the channel and randomly. Fig a: The latex beads are in channel at the applied voltage off.

 High frequency: With the applied voltage on, three different types of particle movement were observed when an AC voltage of 5Vwith various frequencies was applied to the electrode system. Fig b: 10 kHz Fig c: 100 kHz Fig d: 1 MHz Results

 Low frequency: At low frequencies (<5 kHz), the pasticles exhibited unstable behavior by oscillating around the electrode edges and mechanical breakdown. the frequency of 500 Hzthe frequency of 100 Hz Results

 Levitation height: A particle that experiences negative DEP force will be levitated to a certain height above the electrode where the DEP force is balanced by the gravitational force. Newton's first laws : is the gravitational force : is the DEP force the frequency of 100 Hz Results

 Levitation height: A typical dependence of levitation height on the frequency of the applied electric field. Frequency (kHz) The levitation height of the 4.3 μm latex bead Results

 Levitation height: The dependence of levitation height on the value of applied voltage. the frequency of 100 Hz The levitation height increased steadily with the increased applied voltage Results

Conclusion The DEP forces used to manipulate and separate different types of particles. The levitation height of the particles strongly depends on a number of parameters, such as frequencies of the electric field and the applied voltage. The presented DEP-based micro-device has the applications in manipulation and separation of micro particles, particularly bio-particles such as cells, in sample preparation and diagnostic processing.

Reference 1.AC Electrokinetics: colloids and nanoparticles Hywel Morgan and Nicolas G Green 2.A continuous cell separation chip using hydrodynamic dielectrophoresis (DEP) process, Il Doh, Young-Ho Cho 3.Separating Beads and Cells in Multi-channel Microfluidic Devices Using Dielectrophoresis and Laminar Flow

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