Micro elastofluidic liquid diode for programmable unidirectional flow control

Area of Science:

• Microfluidics
• Surface Science
• Wearable Technology

Background:

• Controllable liquid transport is crucial for wearable biosensing platforms.
• Unidirectional flow offers passive liquid movement but lacks real-time tunability in most designs.
• Existing methods for unidirectional flow have limited adaptability and reconfigurability.

Purpose of the Study:

• To develop a tuneable open-channel microfluidic platform with reversible liquid diode behavior.
• To enable dynamic modulation of flow directionality and velocity.
• To demonstrate a passive, pumpless approach for wearable diagnostics and adaptive liquid routing.

Main Methods:

• Developed a microfluidic platform with chevron-ratchet geometry.
• Utilized plasma-induced wettability modulation and mechanical stretching for flow control.
• Established a theoretical force model and conducted numerical simulations based on energy-minimization principles.

Main Results:

• Demonstrated three distinct flow regimes: pinned, unidirectional, and bidirectional.
• Achieved programmable switching of flow states and geometry-sensitive pinning thresholds via mechanical strain.
• Validated sustained unidirectional transport using a hydrogel sweat-acquisition interface.

Conclusions:

• The developed platform offers a simple, tuneable, and reversible liquid diode behavior.
• Surface wettability tuning and mechanical stretching are effective for dynamic flow modulation.
• The open-channel microfluidic platform shows significant translational potential for wearable diagnostics and flexible microfluidic circuitry.