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A 3D passive micromixer with particles of stochastic motion is presented. 3D printing technology and computer numerical control milling technology are employed to manufacture the channel mold with the material of high impact polystyrene. Furthermore, a limonene dissolution method is utilized to dissolve the channel mold. The experimental results demonstrated that the mixing efficiency of the micromixer first increases and then decreases with the increase in the number of particles. Specifically, the mixing efficiency of the micromixer with two cube particles reaches 0.95 with the optimal particle size of 1.5 × 1.5 × 1.5 mm3. In addition, the larger the flow velocity is, the higher the mixing efficiency of the micromixer is. When the flow velocity reaches 1.0 ml/min, the mixing efficiency of the micromixer exceeds 0.9. Compared with the previous micromixers, a 3D passive micromixer with particles of stochastic motion has the advantages of simple manufacturing and no external power. This article is of great significance to the research of micromixers.

A method for manufacturing glass channels with a three-dimensional microstructure array via the micromilling technique is proposed. The three-dimensional microstructure array includes microcolumns, microcones, and microspheres. Then, the glass chip with the three-dimensional microstructure array is bonded with a polydimethylsiloxane chip. To obtain the optimum structure, the experiment of the contact angle is implemented. The results demonstrate that among the three different shapes, the contact angle of the microcolumn array is the largest with a value of 74.3° ± 2.4°. Compared with the other two structures, the microcolumn array is more helpful for continuous liquid mixing. Furthermore, with the increase in the array depth, the contact angle becomes small with the minimum contact angle of 37.9° ± 1.4°. Meanwhile, with the increase in the microcolumn diameter and array spacing, the contact angle becomes large with the maximum contact angle of 83.9° ± 1.4°. In addition, a mixing experiment is developed to verify the practicability of the chip. Compared to other processing methods, this method obtains the advantages of high efficiency and flexibility.