Off-chip passivated-electrode, insulator-based dielectrophoresis (OπDEP)

Area of Science:

• Microfluidics
• Dielectrophoresis
• Biotechnology

Background:

• Traditional electrode-based dielectrophoresis (eDEP) offers sensitivity but lacks high-throughput capabilities.
• Insulator-based dielectrophoresis (iDEP) provides high-throughput and inexpensive devices but often with lower sensitivity.
• A need exists for microfluidic devices combining the sensitivity of eDEP with the throughput of iDEP.

Purpose of the Study:

• To introduce and characterize the first off-chip passivated-electrode, insulator-based dielectrophoresis microchip (OπDEP).
• To demonstrate the OπDEP device's ability to combine eDEP sensitivity with iDEP throughput.
• To showcase the OπDEP device's effectiveness in trapping and concentrating microorganisms from water samples.

Main Methods:

• Developed a novel microfluidic chip design featuring a disposable polydimethylsiloxane (PDMS) microfluidic chip with microposts.
• Utilized a permanent, reusable set of electrodes capacitively coupled to the microfluidic chip, enabling off-chip operation.
• Employed insulator structures and parallel electrodes to generate dielectrophoretic (DEP) forces within the microchannel.

Main Results:

• The OπDEP device generated DEP forces two orders of magnitude larger than conventional off-chip eDEP designs for the same applied voltage.
• Achieved 100% trapping efficiency for Escherichia coli (E. coli) at flow rates up to 400 μL/h, and 60% at 1200 μL/h.
• Demonstrated selective concentration of bacteria from a mixed suspension containing polystyrene beads.

Conclusions:

• The OπDEP technology successfully integrates the advantages of eDEP and iDEP, offering enhanced performance.
• The OπDEP device enables high-throughput and sensitive trapping of microorganisms at flow rates exceeding 1 mL/h.
• This technology holds significant potential for rapid, on-site detection of waterborne pathogens like E. coli.