Protein and Anti-bodies Quantification: AVR-Controlled Negative Dielectrophoresis in Microfluidic Channels

February 28, 2015

In many developing countries, diseases like malaria, tuberculosis, and HIV continue to claim lives due to delayed or inaccessible diagnostics. Early detection is crucial for effective treatment, yet traditional diagnostic tools are often expensive, time-consuming, and require substantial sample volumes— barriers that are particularly pronounced in resource-limited settings. Recognizing this critical need, our research team at the Stanford Genome Research Lab, under the guidance of Professor Ron Davis, embarked on a mission to develop a lab-on-a-chip device that could transform medical diagnostics globally.

The Imperative for Enhanced Protein Quantification

Proteins are the workhorses of biological systems, involved in virtually every cellular process. Accurate quantification of proteins is essential not only for diagnosing diseases but also for advancing biomedical research. Conventional methods like Enzyme-Linked Immunosorbent Assay (ELISA) have been the gold standard for protein detection. However, these techniques often require large sample volumes, lengthy processing times, and specialized laboratory equipment—limitations that hinder their practicality in low-resource environments. This underscores the urgency for rapid, miniaturized assays that offer high sensitivity and specificity without the need for extensive resources.

Leveraging Microfluidics and Negative Dielectrophoresis

Our approach centers on the integration of microfluidics and negative dielectrophoresis (nDEP) to manipulate and analyze proteins at the microscale.

Microfluidics: Precision at a Small Scale

Microfluidics involves the control and manipulation of fluids in channels with dimensions of tens to hundreds of micrometers. This technology allows for precise handling of very small sample volumes, reducing waste and enabling faster reaction times. By miniaturizing the assay environment, we can perform complex biochemical analyses on a single chip, making diagnostics more accessible and efficient.

Technical Implementation

AVR Microcontroller Integration

We employed an AVR microcontroller to precisely control the electric fields necessary for negative dielectrophoresis. The microcontroller generates specific waveforms that create non-uniform electric fields, enabling the manipulation of proteins based on their dielectric properties.

Channel Design and Fabrication

The microfluidic channels were designed using computer-aided design (CAD) software and fabricated using soft lithography techniques. The channel dimensions were optimized to ensure efficient protein separation while maintaining laminar flow conditions.

Results and Validation

Our system demonstrated several key advantages over traditional methods:

  • Sample volume reduction by up to 100-fold
  • Analysis time reduced from hours to minutes
  • Comparable sensitivity to ELISA
  • Significantly lower cost per test
  • Potential for multiplexed detection

Future Directions

While our current prototype shows promising results, we continue to work on:

  • Improving detection sensitivity
  • Expanding the range of detectable proteins
  • Developing a more user-friendly interface
  • Integrating wireless data transmission capabilities
  • Exploring mass production possibilities

Conclusion

Our AVR-controlled microfluidic system represents a significant step toward making protein quantification more accessible in resource-limited settings. By combining microfluidics, negative dielectrophoresis, and smart control systems, we've created a platform that could potentially revolutionize diagnostic capabilities in developing regions.