Room-temperature mL-to-μL quantitative liquid concentration device for cyclone flow

Highly sensitive quantitative analysis of liquids is required in various fields. Analytical instruments and devices such as chromatography, spectroscopic analysis, DNA sequencers, immunoassay, mass spectrometry, and microfluidic devices are utilized for this purpose. Typically, the sample volume is at the milliliter scale, while the analysis volume is at the microliter scale. Consequently, most of the sample is discarded. Therefore, a universal volume interface is required to quantitatively concentrate samples from milliliter to microliter volume. This study introduces a liquid quantitative function to the cyclone concentration method using a millimeter-scale channel, which is highly suitable for controlling liquids at the microliter scale due to its high fluidic resistance against cyclone flow. This method enables the effective control of liquid concentration by cyclone flow. The optimum channel structure is investigated, and a 33-fold concentration of aqueous solutions is demonstrated. Finally, the concentration device is applied to measure molybdenum ions in a river.