UC Berkeley

This paper presents a facile and low-cost fabrication method to construct microfluidic channels by means of a simple candle soot coating process. The fluid channels are defined via a shadow mask fabricated by a Kirigami cutting scheme and placed on top of a hydrophilic substrate. The candle-soot coating process is followed to convert the rest areas with the superhydrophobic property. High-resolution shadow masks can be built via the computer-aided design software. The resulting micro channels are found to have good inert chemical properties and remarkable durability for repeated usages. Three distinctive achievements have been accomplished in this work: 1) an ultra-fast process for the fabrication of microchannels on an area of 18 × 18 mm2 of only ~120 seconds; 2) good lateral channel resolution of ~300 μm; and 3) demonstration of a practical application to detect multiple explosive ions such as and NO2- as well as pH values within ~90 seconds. As such, this low-cost, easy-to-fabricate method is a promising alternative to those of traditional microchannel fabrication techniques.