Robust temperature change rate actuated valving and switching for highly integrated centrifugal microfluidics

Area of Science:

• Microfluidics
• Biotechnology
• Mechanical Engineering

Background:

• Centrifugal microfluidics offers precise fluid handling but requires robust valving and switching mechanisms.
• Existing methods often involve complex fabrication or additional components, increasing costs and limiting integration.

Purpose of the Study:

• To introduce novel, cost-effective unit operations for valving and switching in centrifugal microfluidics.
• To demonstrate control of these operations using temperature change rate (TCR) and rotational frequency.
• To validate the compatibility and robustness of these methods for integrated assays.

Main Methods:

• Implementation of valving/switching via fluidic resistance in an air vent, creating thermally induced underpressure.
• Control of thermally induced underpressure using TCR and centrifugal counterpressure adjusted by rotational frequency.
• Analytical modeling and experimental verification of the TCR-actuated unit operations.

Main Results:

• Demonstrated a stand-alone switch routing liquid to collection chambers.
• Validated robust TCR-actuated valving within a microfluidic cartridge for nucleic acid testing.
• Quantified pressure ranges for preventing or enabling valving during PCR and for siphon valving.

Conclusions:

• TCR-actuated valving and switching provide a simple, cost-effective solution for centrifugal microfluidics.
• Independent control via TCR and rotational frequency allows flexible integration into existing protocols.
• These unit operations are suitable for advanced applications like integrated nucleic acid testing.