Micro wet analysis system using multi-phase laminar flows in three-dimensional microchannel network

Abstract

A three-dimensional microchannel network with two-level crossings of channels was constructed in a glass microchip by sandwiching an insulating glass plate between two glass plates with microchannels followed by thermal bonding. Pressure-driven stable multi-phase laminar flows inside the three-dimensional channel network were realized by balancing flow rates of syringe pumps. Micro unit operations for mixing, reaction, solvent extraction, and detection were properly arranged in the multi-phase laminar flows, so that four parallel analyses, comprising twenty unit operations in total, could be integrated onto a single chip. Two chelating reagents and two sample solutions containing heavy metal ions (Fe(II) or Co(II)) were mixed and reacted in four different combinations using the three-dimensional channel network. After chelating reactions were completed, post processing (solvent extraction or addition of acid) was applied to each solution stream to remove the interferences of coexisting metal ions. Finally, target metal complexes were detected using a thermal lens microscope (TLM). Integrity of the micro system was confirmed by qualitative analysis of Fe(II) and Co(II). This is the first example of continuous flow chemical processing utilizing multi-phase laminar flow realized in a three-dimensional channel network.