On-Chip Impedance for Quantifying Parasitic Voltages During AC Electrokinetic Trapping

Area of Science:

• Microfluidics
• Electrical Engineering
• Biophysics

Background:

• Assessing microfluidic device effectiveness for electrokinetic or acoustic trapping typically requires microscopy.
• This conventional method is time-consuming, requires specialized equipment, and relies on trained personnel.
• Valuable biological samples are often used, increasing the cost and complexity of assessment.

Purpose of the Study:

• To develop an alternative, electrical method for assessing microfluidic device performance.
• To identify device geometry variations that lead to poor particle trapping.
• To avoid the need for microscopy and reduce reliance on trained operators.

Main Methods:

• An on-chip method was developed to acquire impedance spectra of microfluidic devices.
• The study focused on AC electrokinetic trapping in a contact-less dielectrophoresis (DEP) mode over an insulated channel.
• Parasitic voltage drops within the microfluidic device were quantified using impedance measurements.

Main Results:

• The on-chip impedance measurement successfully quantified parasitic voltage drops.
• The method demonstrated its utility in assessing AC electrokinetic trapping effectiveness.
• Device geometries were correlated with measured parasitic voltage drops.

Conclusions:

• Device geometries can be optimized based on parasitic voltage drop measurements to maximize the voltage available for DEP manipulation.
• On-chip impedance measurements provide a rapid feedback mechanism for optimizing microfluidic device design.
• This electrical approach facilitates efficient downstream decision-making for particle manipulation in microfluidic systems.