Automated paper-based devices by microfluidic timing-valve for competitive ELISA

We present a timing-valve mechanism on a paper-based device to conduct competitive ELISA procedures. The device consists of multiple channels, where timing-valves regulate each individual liquid flow, to automate sequential steps. The timing-valve is achieved using surfactants to dissolve the hydrophobic barriers and to allow fluid to pass through in a timed duration. Imidacloprid (small molecule pesticide) is tested in our proposed device, while the results validate a simplified fluidic manipulation procedure and permits only single-step application of the sample solution for on-site detection.