Microfluidic valve with zero dead volume and negligible back-flow for droplets handling

摘要

Highlights•Microvalve prepared as monolithic PDMS device showing negligible back-flow volume.•The fabricated microvalve can sustain high pressure operations (up to 4bar).•Fabrication combines 3D printing, PDMS replica molding and wire-removal strategy.•Droplets can pass through the valve without been damaged or perturbed.•Valve is suitable for Droplet-on-Demand generation and droplet sorting.AbstractDroplet microfluidics allows the implementation of several biochemical and bioanalytical protocols in microfluidic devices. However, this integration typically requires the use of microfluidic valves, which allow the control of different operations on the same channels network. Unfortunately, the valves commercially available are almost exclusively suitable for-single phase flow, and only one valve system compatible with multi-phase systems has been presented so far in the literature. We present here a new pinch-like valve that withstands high pressures (tested up to 4bar), allows droplet manipulation and combines the advantages of conventional pinch valves regarding the absence of dead volume, while making negligible the backflow generated (less than 2nL). The conception and design of the presented valve, based on numerical simulations, is performed by an optimized microfabrication strategy, combining PDMS soft-lithography and 3D printing technologies. The valves had been tested regarding their mechanical stability and proving their capability of allowing droplets passing through them, without any perturbation. Finally, the very small back-flow volume generated during the actuation, has been exploited for various applications in droplets microfluidics, like droplet handling, droplet-on-demand generation and sorting.