Multi-channel PMMA microfluidic biosensor with integrated IDUAs for electrochemical detection.

Area of Science:

• Electrochemistry
• Microfluidics
• Biosensing

Background:

• Microfluidic devices offer miniaturization and high throughput for bioanalysis.
• Simultaneous detection in microfluidic systems requires robust electrode integration and channel design.
• Existing single-channel devices limit parallel analysis capabilities.

Purpose of the Study:

• To develop a novel multi-channel poly(methyl methacrylate) (PMMA) microfluidic biosensor.
• To achieve simultaneous electrochemical detection using a large interdigitated ultramicroelectrode array (IDUA) across multiple microchannels.
• To demonstrate the device's utility in nucleic acid quantification.

Main Methods:

• Fabrication of PMMA microfluidic channels and IDUAs using UV/ozone-assisted thermal bonding.
• Optimization of gold adhesion, protective coatings, and bonding pressure for device ruggedness.
• Electrochemical performance evaluation using amperometric detection of potassium ferri/ferro hexacyanide and coulometric detection of DNA sequences.

Main Results:

• Demonstrated linearity (R(2)=0.98) from 0-38 μM and a limit of detection of 3.48 μM for potassium ferri/ferro hexacyanide.
• Achieved highly reproducible signals comparable to single-channel devices with no cross-talk between channels.
• Successfully quantified specific nucleic acid sequences with a limit of detection of 12.5 μM within 250 s.

Conclusions:

• The developed multi-channel microfluidic biosensor provides a reliable platform for simultaneous electrochemical detection.
• The device exhibits excellent linearity, reproducibility, and low detection limits for both small molecules and nucleic acids.
• This robust, high-throughput design is well-suited for multianalyte bioanalytical applications and future high-throughput assays.