Capillary driven low-cost V-groove microfluidic device with high sample transport efficiency.

In this study we investigate the liquid sample delivery speed and the efficiency of microfluidic channels for low-cost and low-volume diagnostic devices driven only by capillary forces. We select open, non-porous surface grooves with a V-shaped cross section for modeling study and for sensor design. Our experimental data of liquid wicking in V-grooves show an excellent agreement with the theoretical data from the V-groove model of Rye et al. This agreement allows us to quantitatively analyze the liquid wicking speed in V-grooves. This analysis is used to generate data for the design of sensors. By combining V-groove channels and printable paper-like porous detection zones, microfluidic diagnostic sensors can be formed. Non-porous V-grooves can be fabricated easily on polymer film. Suitably long surface V-grooves allow short liquid transport time (<500 ms), thus reducing the evaporation loss of the sample during transport. Non-porous V-grooves also significantly reduce chromatographic loss of the sample during transport, therefore increasing the sample delivering efficiency. Sensors of such design are capable of conducting semi-quantitative chemical and biochemical analysis (i.e. with a calibration curve) with less than 1000 nL of sample and indicator solution in total.