A low-cost and high-performance 3D micromixer over a wide working range and its application for high-sensitivity biomarker detection

Homogenous mixing in microfluidic devices is often required for efficient chemical and biological reactions. Passive micromixing without external energy input has attracted much research interest. We have developed a high-performance 3D micromixer over a wide range of Reynolds number (Re) and viscosity, which was fabricated in a low-cost method of 3D printing. The characterization of the 3D printer was performed by measuring the surface roughness and fabrication error. The mixing mechanism and performance of the micromixer were investigated through numerical simulations and experiments. Influences of geometry parameters, including length, rotation direction and connection angle of helical elements, were also investigated. The mixing performance of the micromixer was studied over an ultra-wide range of flow rates from 0.3 to 70 000 μL min⁻¹ (Re = 0.01-2333.3). The mixer presented an excellent mixing performance, with a mixing efficiency of more than 96.5% for water and more than 85.1% for solutions with viscosities nearly 13 times that of water. The micromixer can achieve rapid mixing with a mixing time of 883.7 μs for aqueous solutions. In addition, the high-performance micromixer was integrated into a versatile electrochemical detection platform to enhance enzyme-catalyzed reactions. The bare microelectrode array (μEA) on the detection platform has a wide linear detection range to sarcosine from 30 to 1000 μM with a limit of detection (LOD) of 9.7 μM. The highest sensitivity for sarcosine detection (281.7 μA mM⁻¹ cm⁻²) and enhancement of current response up to 57.1% were achieved on the detection platform. This work broadens the scope of micromixer applications and sheds new light on the development of high-performance micromixers.