Active micromixers have been widely used in chemistry, biomedicine and many micro analyses as it offers low reagent consumption, controllable mixing process, safe, and reliable. Based on piezoelectric (PZT) drive technology and numerical simulation results, a self-circulation micromixer with high frequency vibration has been designed and fabricated. The micromixer is composed of PZT micropump, vibration substrate, mixing pool with double U-shaped inlet and outlet, upper cover plate and lower substrate. The performance of the micromixer’s self-circulation and high frequency vibration is evaluated by experimental tests. Experimental results show that: When the drive voltage and frequency of the self-circulation reflux micropump are set to 100 V and 100 Hz, respectively, a significant vortex flow is generated in the mixing pool, and the vortex flow speed is as high as 320 r min−1. When the driving frequency of the vibration substrate is set to its first resonance frequency, the displacement of its center point is the largest up to 28.1 µm. Furthermore, the vortex flow speed of the fluid in the mixing pool and the vibration intensity of the vibration substrate can be adjusted separately by regulating the driving voltage of the PZT micropump and vibration substrate.

On the basis of liquid-phase reduction mechanism, a novel synthesis method to prepare silver nanoparticles (AgNPs) is proposed, which uses piezoelectric-actuated three-phase flow pulsating mixing microfluidic chip. In order to study and explore the influence of different factors on the synthesis of AgNPs, a series of related synthesis experiments were carried out. e corresponding experimental conditions include the concentration of sodium hydroxide and reducing agent solution, polyvinylpyrrolidone (PVP) dosage, inlet flow rate, and synthesis temperature.e synthesized AgNPs were characterized by the UV-Vis absorption spectrophotometer and transmission electron microscopy. e effects of different experimental conditions on the controllable synthesis of AgNPs were analyzed, and the optimum synthesis conditions of AgNPs were obtained. Experimental results show that the spherical AgNPs with an average particle diameter of about 29 nm, high yield, fine morphology, and good monodispersity were synthesized using the microfluidic chip under the conditions of the working frequency (200 Hz), the initial concentration of silver nitrate (1 mM), the synthesis temperature (80°C), the concentration ratio of sodium hydroxide to silver nitrate (2 : 1), the concentration ratio of glucose to silver nitrate (4 : 1), the inlet flow rate (3.5 ml/min), and the quality ratio of PVP to silver (more than 1 : 1). e related research shows that it is an efficient synthesis method to develop the controllable synthesis experiments of AgNPs under multifactors using the three-phase pulsating mixing microfluidic chip.

Background: The diagnostic accuracy of CT-derived fractional flow reserve (CT-FFR) in clinical application has been well validated. This advanced technology focus on evaluating anatomical stenosis and functional ischemia simultaneously. However, the effect of CT-FFR on the management of decision making has not been fully evaluated in randomized controlled design. Method/design: TARGET study is a pragmatic, multicentre, prospective, open-label and randomized controlled trial evaluating the effect of a CCTA/CT-FFR strategy (Group A) versus usual care (Group B) on intermediate-to-high risk patients with suspected CAD who undergo clinically indicated diagnostic evaluation. A total sample size of 1216 subjects will be enrolled and followed up for 12 months. This study will be performed in 6 Chinese hospitals, and the primary endpoint is the planned ICA without significant obstructive CAD within 90 days. The secondary endpoints include MACE, quality of life, medical expenditure, and cumulative radiation exposure during 1-year follow-up.Disscusion: The study will provide information to patients, health care providers and other stakeholders in China about which strategy could be more effective in the management of intermediate-to-high risk patients with suspect CAD.Trial registration:ClinicalTrials.gov, NCT03901326, Registered on 03 April 2019.

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A micromixer with two-layer crossing microchannels based on PMMA bonding process was proposed. The micromixer consists of two-layer crossing microchannels and periodic mixing chambers. The numerical simulation and parameters optimization of the micromixer were carried out in a Reynolds number range of 0.5–100 using CFD software, and the prototype of micromixer was manufactured by PMMA bonding process under certain temperature and pressure condition. The mixing performance of the micromixer was tested and verified by the mixing experiments using red-blue dye. Both the numerical and experimental results confirmed that the micromixer achieves an excellent mixing characteristics over a wide range of Reynolds numbers through generating Dean vortices and chaotic advection. At the same time, the PMMA bonding process proposed in this paper has certain application value and reference significance for expanding the application of three-dimensional flow channels in the field of microfluidics.