Microfluidic valves made from polymerized polyethylene glycol diacrylate

Abstract

Pneumatically actuated, non-elastomeric membrane valves fabricated from polymerized polyethylene glycol diacrylate (poly-PEGDA) have been characterized for temporal response, valve closure, and long-term durability. A ~100 ms valve opening time and a ~20 ms closure time offer valve operation as fast as 8 Hz with potential for further improvement. Comparison of circular and rectangular valve geometries indicates that the surface area for membrane interaction in the valve region is important for valve performance. After initial fabrication, the fluid pressure required to open a closed circular valve is ~50 kPa higher than the control pressure holding the valve closed. However, after ~1000 actuations to reconfigure polymer chains and increase elasticity in the membrane, the fluid pressure required to open a valve becomes the same as the control pressure holding the valve closed. After these initial conditioning actuations, poly-PEGDA valves show considerable robustness with no change in effective operation after 115,000 actuations. Such valves constructed from non-adsorptive poly-PEGDA could also find use as pumps, for application in small volume assays interfaced with biosensors or impedance detection, for example.

3D printed microfluidic devices with integrated valves

“…We find that the valve membrane typically breaks sometime after 800 actuations. Given our earlier results for poly-PEGDA microfluidic valves where over 100 000 actuations resulted in little change in performance, 34 we are confident that lifetimes of 3D printed microfluidic valves can be dramatically increased.…”

“…We modified our previous resin formulation 34 for use in a B9 Creator 3D printer by replacing the original photoinitiator, 2,2-dimethoxy-2-phenylacetophenone (DMPA), with Irgacure 819 and adding an absorber dye, Sudan I. The B9 Creator's light source is a commercial XGA (1024 Â 768 pixels) projector which does not emit UV light.…”

“…33 More recently, we demonstrated that despite having a significantly larger bulk modulus than PDMS (>100 MPa compared to $0.5 MPa), our poly-PEGDA material can be configured in a 3-layer design to create a membrane-type valve with compelling characteristics: 19 ms closure time and 115 000 actuations with no degradation in performance. 34 Although 3D printed devices have excellent potential for biomedical microfluidic applications, current methods have limitations in terms of resolution, resin versatility, overall device dimensions, and/or prototyping system cost. Moreover, in all cases, the reported 3D printed microfluidic devices are composed of only passive elements.…”

“…34 Briefly, two pressure sensors were placed in-line to monitor both the air pressure applied to close a valve and the fluidic pressure applied at the front of the device used to open the valve. A CCD camera was used to track the meniscus at the device outlet which was then converted to volumetric flow rate.…”

“…Meanwhile, a syringe pump introduces fluid into the valve inlet while the fluid pressure (blue circle marked curve, left axis) and flow rate at the valve outlet (solid green curve, right axis) are monitored (see Ref. 34 for further details on the measurement method). As expected, the fluid pressure increases within the device as a function of time until it reaches approximately the control pressure that is used to close the valve membrane.…”