Programmable active droplet generation enabled by integrated pneumatic micropumps

Abstract

In this work we have investigated the integrated diaphragm micropump as an active fluidic control approach for the on-demand generation of droplets with precisely defined size, frequency and timing. In contrast to valve-actuated devices that only modulate the flow of the dispersed phase being continuously injected, this integrated micropump allows the combination of fluidic transport and modulation to achieve active control of droplet generation. A distinct characteristic of this method compared to the valve modulated droplet formation processes is that it enables independent control of droplet generation frequency by adjusting the pumping frequency and droplet size by flow conditions. We also demonstrated the generation of complex droplet patterns through programming the pumping configurations and the application to multi-volume digital PCR for precise and quantitative detection of genetic targets. Overall, our results suggest that the pump-based droplet microfluidics provide a robust platform for programmable active droplet generation which could facilitate the development of high-performance chemical and biological assays.

Digital PCR using micropatterned superporous absorbent array chips

“…6, 9, 15 The average concentrations and their expanded uncertainties at a confidence level of 95% were calculated following the approach described by Pinheiro, et al for evaluating two commercial dPCR instruments, 46 which permits direct comparison with their results. As presented in Fig.…”

“…The results were compared to that obtained using the microfluidic droplet dPCR technology that we established previously (see Supporting Information for details). 6, 9, 15 …”

A droplet-based fluorescence polarization immunoassay (dFPIA) platform for rapid and quantitative analysis of biomarkers

“…Importantly, the incorporation of integrated pneumatic micro-pumps system with the dropletbased microfluidic systems obviates the need syringe-pumps or large dead-volume connections . It should be noted that some studies incorporating pneumatic micro-pumps within microfluidic systems have recently been reported (Sun et al, 2013;Zeng et al, 2013). However, the system described herein possesses additional desirable features; most notably complete pump integration (removing the need for external syringe pumps), simple operation via single step actuation and facile device fabrication.…”

Droplet microfluidics: A tool for biology, chemistry and nanotechnology

“…Standard methods exist to generate droplets, either in a hydrodynamically driven manner (e.g., flow focusing, co-axial and T-junction geometries) or in a manner driven by an external force (e.g., droplet generation based on an electromagnetic valve that provides the ability to produce a droplet on demand [11] or droplet generation by pneumatic micropumps) [12]. Recently, new methods have been introduced to increase the rate of generating and producing droplets, for example, by introducing gradient confinement [13] or by parallelizing conventional structures [14].…”