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...

Nanoparticle-functionalized transition-metal carbides and nitrides (MXenes) have attracted extensive attention in electrochemical detection owing to their excellent catalytic performance. However, the mainstream synthetic routes rely on the batch method requiring strict experimental conditions, generally leading to low yield and poor size tunability of particles. Herein, we report a high-throughput and continuous microfluidic platform for preparing a functional MXene (Ti 3 C 2 T x ) with bimetallic nanoparticles (Pt−Pd NPs) at room temperature. Two 3D micromixers with helical elements were integrated into the microfluidic platform to enhance the secondary flow for promoting transport and reaction in the synthesis process. The rapid mixing and strong vortices in these 3D micromixers prevent aggregation of NPs in the synthesis process, enabling a homogeneous distribution of Pt−Pd NPs. In this study, Pt−Pd NPs loaded on the MXene nanosheets were synthesized under various hydrodynamic conditions of 1−15 mL min −1 with controlled sizes, densities, and compositions. The mean size of Pt−Pd NPs could be readily controlled within the range 2.4−9.3 nm with high production rates up to 13 mg min −1 . In addition, synthetic and electrochemical parameters were separately optimized to improve the electrochemical performance of Ti 3 C 2 T x /Pt−Pd. Finally, the optimized Ti 3 C 2 T x /Pt−Pd was used for hydrogen peroxide (H 2 O 2 ) detection and shows excellent electrocatalytic activity. The electrode modified with Ti 3 C 2 T x /Pt−Pd here presents a wide detection range for H 2 O 2 from 1 to 12 000 μM with a limit of detection down to 0.3 μM and a sensitivity up to 300 μA mM −1 cm −2 , superior to those prepared in the traditional batch method. The proposed microfluidic approach could greatly enhance the electrochemical performance of Ti 3 C 2 T x /Pt−Pd, and sheds new light on the large-scale production and catalytic application of the functional nanocomposites.

PDMS-based micropillar array electrodes with increased surface area and surface modification were developed to detect biomarkers with high sensitivity.

No abstract

Micromixers play an important role in the micro total analysis systems (µTAS) that require rapid and effective mixing. However, current micromixers are usually designed to meet the need for mixing at limited Reynolds numbers. Herein, this paper presents a high‐performance 3D micromixer with helical elements over wide Reynolds numbers to achieve efficient mixing and has numerically investigated flow patterns and mixing characteristics accordingly. A coupled numerical model is built to analyze the flow pattern, mixing behavior, residence time distribution (RTD), and mixing performance of the 3D micromixer. Helical elements inside could greatly enhance a secondary flow and induce chaotic advection around. Dean vortices are observed in the micromixer, enormously shortening the RTD and promoting the related mixing effect. Furthermore, the effects of various geometric parameters are systematically investigated to optimize the performance of this 3D micromixer. The optimized micromixer shows excellent mixing ability over wide Reynolds numbers ranging from 0.01 to 2333.3, with an efficiency of over 94%. In addition, the numerical results are proved well consistent with analytical and experimental data correspondingly. Therefore, this work would potentially expand the use scope of 3D micromixers and provide a constructive strategy to develop essential parts involving the mixing or reacting process in µTAS.