Chip for dielectrophoretic microbial capture, separation and detection II: experimental study.

Area of Science:

• Microfluidics
• Biophysics
• Electrical Engineering

Background:

• Previous modeling established dielectrophoretic force (DEP) and cell behavior in microfluidic channels.
• Experimental validation is needed for theoretical design constraints of electrode architectures.

Purpose of the Study:

• To experimentally validate the theoretical design constraints of a ring electrode architecture for microbial capture.
• To compare the performance of ring and dot electrode designs in bacterial capture and separation.
• To investigate the electroosmosis (EO) to positive dielectrophoresis (PDEP) transition and its effect on capture efficiency.

Main Methods:

• Experimental testing of ring and dot electrode designs in a microfluidic channel.
• Investigating bacterial motion in response to applied electric fields.
• Quantitative evaluation of the EO to PDEP transition and capture efficiency.

Main Results:

• The ring electrode structure demonstrated 99% bacterial capture efficiency for both PDEP and EO.
• The ring structure exhibited over 200x faster bacterial response to the electric field compared to the dot structure.
• Efficient microbial cell capture and separation were achieved with the ring electrode architecture, with critical design constraints identified.

Conclusions:

• The ring electrode architecture is highly effective for microbial capture and separation in microfluidic devices.
• Optimized periodicity and spacing of DEP traps are crucial for efficient bacterial capture.
• Ensuring DEP trap spacing is smaller than the depletion zone length maximizes DEP force dominance over other motion types.