Microfluidic Concentration Gradient Chip for Drug Susceptibility

Device engineering for microbial testing

Overview

A research project developing a microfluidic concentration gradient chip for rapid and cost-effective gradient-based microbial drug susceptibility testing, with applications in clinical microbiology and antimicrobial resistance monitoring.

Intellectual Property

  • 1 Invention Patent: Microfluidic device with gradient generation
  • 1 Utility Model Patent: Manufacturing and assembly optimization

Publication

Published in Chinese Journal of Medical Physics, 2021.

Shi, H., Cao, Y., Zhou, Y., et al. “Development and Application of Microfluidic Concentration Gradient Chip”

Funding

PhD Research Startup Fund: EA202008205

Clinical Significance

Traditional microbial drug susceptibility testing faces challenges:

  • Time-consuming: 24-72 hour culture requirement
  • Resource intensive: Large sample volumes needed
  • Labor demanding: Manual preparation and interpretation
  • Reproducibility issues: Concentration gradient variability

Key Innovations

Device Design

  • Gradient Generation: Passive mixing via diffusion and hydrodynamic focusing
  • Concentration Range: 8-point logarithmic gradient (1-1000 µM)
  • Precision: ±5% concentration uniformity across gradient
  • Integration: Multiple testing zones on single chip

Microfluidic Principles

  • Laminar Flow: Reynolds number control for stable gradients
  • Channel Design: Optimized geometry for rapid equilibration
  • Valve Integration: On-chip sample loading and routing
  • Biocompatibility: PDMS substrate with surface coatings

Experimental Validation

Performance Metrics

  • Concentration Linearity: R² > 0.98
  • Temporal Stability: <2% drift over 4 hours
  • Spatial Uniformity: ±3% across transverse direction
  • Reproducibility: Inter-chip CV < 5%

Microbial Testing

  • Organism Coverage: E. coli, S. aureus, P. aeruginosa
  • Drug Panels: Aminoglycosides, fluoroquinolones, β-lactams
  • MIC Accuracy: ±1 dilution of reference (EUCAST)
  • Time Reduction: 6-8 hours vs. 24-72 hours traditional

Clinical Applications

  • Antibiotic Stewardship: Rapid resistance detection
  • Point-of-Care Testing: Decentralized susceptibility assessment
  • Infection Control: Quick turnaround for severe infections
  • Epidemiology: Large-scale resistance surveillance

Manufacturing

  • Fabrication Method: Soft lithography with PDMS molding
  • Scale-Up: Compatible with mass production
  • Cost: <$5 per chip vs. >$20 for traditional methods
  • Shelf Life: 12+ months at 4°C

Collaborators

A/Prof. Shi Huanhuan - Associate Professor, Department of Biomedical Engineering

Future Directions

  • Multi-pathogen detection panels
  • Integration with smartphone microscopy
  • Real-time growth kinetics monitoring
  • AI-assisted result interpretation

Timeline

  • Start: December 2019
  • End: December 2021
  • Duration: 24 months
  • Publication: 2021