A 3D Printed Jet Mixer for Centrifugal Microfluidic Platforms

Efficient Mixing of Microfluidic Chip with a Three-Dimensional Spiral Structure

In this paper, a helical three-dimensional (3D) passive micromixer is presented. A three-dimensional spiral passive micromixer is fabricated through the 3D printing technology and the polymer dissolution technology. The main process is as follows: First of all, a high-impact polystyrene (HIPS) material was used to make a 3D spiral channel mold. Second, the channel mold was dissolved in limonene solvent. The mixing experiment shows that the single helix structure can improve the mixing efficiency to 0.85, compared with the mixing efficiency of 0.78 in the traditional T-shaped two-dimensional (2D)-plane channel. Different screw diameters, screw number structures, and flow rates are used to test the mixing effect. The optimal helical structure is 5 mm, and the flow rate is 2.0 mL/min. Finally, the mixing efficiency of the 3D helical micromixer can reach 0.948. The results show that the three-dimensional helical structure can effectively improve the mixing efficiency.

Editorial for the Special Issue on Analysis, Design and Fabrication of Micromixers

During the last couple of decades, there have been rapid developments in analysis, design, and fabrication of micromixers [...].

On-Chip Micro Mixer Driven by Elastic Wall with Virtual Actuator

In this paper, we propose an on-chip micromixer driven by an elastic wall with a virtual actuator. The on-chip micro mixer is composed of a circular chamber surrounded by a ring-shaped channel under isolation with an elastic wall. When vibrational pressure is put on the driving channel by an actuator, the volume of the circular chamber changes through the deformation of the elastic wall, as if there exists a virtual actuator near the wall. As a result, the liquid in the circular chamber is pushed out and pulled through the neck channel. This action creates a swirling flow in the circular chamber while maintaining isolation from the driving channel. Through experiments, we confirmed the swirling flow under an isolated environment using an air-based valve. The advantage of this approach is that the micromixer can be designed with a single layer having a simple mechanism.

Push/Pull Inequality Based High-Speed On-Chip Mixer Enhanced by Wettability

In this paper, a high-speed on-chip mixer using two effects is proposed, i.e., push/pull inequality and wettability. Push/pull inequality and wettability are effective for generating a rotational fluid motion in the chamber and for enhancing the rotational speed by reducing the viscous loss between the liquid and channel wall, respectively. An on-chip mixer is composed of three components, a microfluidic channel for making the main fluid flow, a circular chamber connected to the channel for generating a rotational flow, and an actuator connected at the end of the channel allowing a push/pull motion to be applied to the liquid in the main channel. The flow patterns in the chamber under push/pull motions are nonreversible for each motion and, as a result, produce one-directional torque to the fluid in the circular chamber. This nonreversible motion is called push/pull inequality and eventually creates a swirling flow in the chamber. Using hydrophilic treatments, we executed the experiment with a straight channel and a circular chamber to clarify the mixing characteristics at different flow speeds. According to the results, it is confirmed that the swirling velocity under appropriately tuned wettability is 100 times faster than that without tuning.