Fabrication of Embedded Microvalve on PMMA Microfluidic Devices through Surface Functionalization

TL;DR

This paper presents a method to fabricate embedded microvalves in PMMA microfluidic devices by surface functionalization, enabling pneumatic control with low pressure and reliable bonding between PMMA and PDMS layers.

Contribution

It introduces a surface functionalization technique using air plasma corona treatment for permanent bonding of PMMA to PDMS in multilayer microfluidic devices.

Findings

Air plasma corona treatment effectively increases PMMA hydrophilicity.

Bonded PMMA multilayer devices withstand fluid pressures up to 9 μL/min.

Embedded PDMS membranes actuate at pneumatic pressures as low as 10 kPa.

Abstract

The integration of a PDMS membrane within orthogonally placed PMMA microfluidic channels enables the pneumatic actuation of valves within bonded PMMA-PDMS-PMMA multilayer devices. Here, surface functionalization of PMMA substrates via acid catalyzed hydrolysis and air plasma corona treatment were investigated as possible techniques to permanently bond PMMA microfluidic channels to PDMS surfaces. FTIR and water contact angle analysis of functionalized PMMA substrates showed that air plasma corona treatment was most effective in inducing PMMA hydrophilicity. Subsequent fluidic tests showed that air plasma modified and bonded PMMA multilayer devices could withstand fluid pressure at an operational flow rate of 9 mircoliters/min. The pneumatic actuation of the embedded PDMS membrane was observed through optical microscopy and an electrical resistance based technique. PDMS membrane actuation occurred at pneumatic pressures of as low as 10kPa and complete valving occurred at 14kPa for 100 micrometers x 100 micrometers channel cross-sections.