ABSTRACT
Flexible power sources are crucial to developing flexible electronic systems; nonetheless, the current poor stretchability and stability of flexible power sources hinder their application in such devices. Accordingly, the stretchability and fatigue stability of flexible power sources are crucial for the practical application of flexible electronic systems. In this work, a flexible electrode with an arc-shaped star concave negative Poisson's ratio (NPR) structure is fabricated through the screen printing process. Using the combination of finite element analysis (FEA) and tensile tests, it is proven that the arc-shaped star concave NPR electrode can effectively reduce the maximum tensile stress and increase the maximum elongation (maximum elongation 140%). Furthermore, the flexible electrodes prepared in this study are assembled into all-solid-state symmetric supercapacitors (SSCs), and their electrochemical properties are tested. The SSC prepared in this study has a high areal capacitance of 243.1 mF cm-2. It retains 89.25% of its initial capacity after 5000 times of folding and can maintain a stable output even in extreme deformation, which indicates that the SSC prepared in this study has excellent stability. The SSC with the advantages mentioned above obtained in this study is expected to provide new opportunities to develop flexible electronic systems.
ABSTRACT
Flexible microfluidic chips have good application prospects in situations with easy bending and complex curvature. An important factor affecting the flexible microfluidic chip is its structural complexity. For example, the hybrid chip includes flow channels, mixing chambers, and one-way valves. How to achieve the same function with as few structures as possible has become an important research topic at present. In this paper, a Tesla valve micromixer with unidirectional flow characteristics is presented. A passive laminar flow Tesla valve micromixer is fabricated through 3D printing technology and limonene dissolution method. The main process is as follows: First of all, high impact polystyrene (HIPS) material was employed to make the Tesla valve channel mold. Second, the channel mold was dissolved in the limonene solvent. The mold of Tesla micromixer is made of HIPS material, the mixing experiment displace that the Tesla valve micromixer is characterized by unidirectional flow compared with the common T-shaped planar channel. At the same time, the 5-AAC Tesla valve micromixer can increase the mixing efficiency to 87%. By using four different groove structures and different flow rates of the mixing effect experiment, the conclusion is that the mixing efficiency of the 6-AAC Tesla valve micromixer is up to 0.89 when the flow rate is 2 mL/min. The results manifest that the Tesla valve structure can effectively improve the mixing efficiency.
ABSTRACT
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.
