Design and fabrication of integrated solid-phase extraction-zone electrophoresis microchip

Area of Science:

• Microfluidics
• Analytical Chemistry
• Polymer Science

Background:

• Microchip electrophoresis offers miniaturized analytical capabilities.
• Integrated sample preparation enhances analytical throughput and reduces contamination.
• SU-8 polymer is a versatile material for microfabrication due to its photolithographic properties.

Purpose of the Study:

• To design and fabricate an integrated solid-phase extraction-zone electrophoresis (SPE-ZE) microchip.
• To evaluate the performance of the fabricated SPE-ZE device for analyte separation.
• To demonstrate the utility of SU-8 polymer for creating complex microfluidic structures with high aspect ratios.

Main Methods:

• Fabrication of the SPE-ZE device using multi-layered SU-8 photolithography and adhesive bonding.
• Integration of a fluidic reservoir with bead filters for solid-phase extraction (SPE).
• Design of a 25 mm electrophoresis channel coupled to the SPE unit.
• Utilizing Argon laser-induced fluorescence (LIF) detection for simultaneous monitoring.
• Simulation of flow characteristics and electric field distributions using Femlab software.

Main Results:

• Successful fabrication of the integrated SPE-ZE microchip with high aspect ratio pillars and uniform microchannels.
• Demonstration of on-chip SPE functions including adsorption, bead rinsing, and elution.
• Verification of the device's operational performance using fluorescein as the analyte.
• Validation of simulated flow and electric field characteristics.

Conclusions:

• The developed SU-8 based SPE-ZE microchip provides an effective platform for integrated sample preparation and electrophoretic separation.
• The novel fabrication technique ensures high yield and precise alignment of microfluidic components.
• This integrated device holds promise for rapid and sensitive on-chip chemical analysis.