A comblike time-valve used in capillary-driven microfluidic devices

Capillary-driven microfluidic devices can provide rapid on-site diagnostic results. It has gained more concerns over the years. Time-valve, which can provide enough reaction time for the target ligand and the test reagent, is an important module in the device. Traditional microfluidic valves usually have complicated and small line-width structures, which may limit their use in the mass production of the devices. Here, a comblike time-valve is presented. The valve comprises of a number of parallel comblike protrusions and interval channels. The time that the liquid takes to pass through the valve can be readily controlled by changing the number of the comblike protrusions. The effects of the valve's size parameters on flow time control have been studied. Results show that the valve can delay the liquid flow from several tens of seconds to several minutes, which will provide an accurate time control for the reaction between the target ligand and the test reagents. This time-valve has a simple structure with a minimal line-width above 100 pm. It can be readily fabricated and integrated onto a capillary-driven microfluidic device for mass production and quantitative diagnostics. (C) 2017 Elsevier B.V. All rights reserved.