Compact sampling device based on wax microfluidics

Abstract

There is an increasing demand for sampling devices that can provide spatial and temporal information on water quality. Microfluidic systems, applied in combination with the rapid developments in unmanned vehicles (i.e. drones) show the potential to address this challenge. This work reports on the design, fabrication and performance of a low-cost, self-contained sampling device based on a wax microfluidics technology. The sampler with a total size of 18.25×18.25mm2 integrates 14 electrically controlled wax microvalves that connect the collection outlets to the central chamber. These new wax microvalves are capable of multiple actuation and have small-footprint (0.2mm2), fast-response (≤0.15s), and very low energy consumption (<25mJ). The sampler device is simple to operate, leak-proof to at least 100kPa and can be easily fabricated in a single wax stamp transfer using soft-lithography. Water samples containing known concentrations of heavy metals were collected using the wax-valve sampler and further analysed by ICP-MS demonstrating the perfect isolation of the collected samples. Thanks to its small size and low power requirements, the sampler devices described here could be very useful for water sampling from small unmanned vehicles like underwater drones.