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Size-Dependent Behavior of Micro/Nano-Structures and Systems
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  • RESEARCH ARTICLE
    Kaikai LI, Longsheng LU, Huaping CHEN, Guoxiang JIANG, Huanwen DING, Min YU, Yingxi XIE
    Frontiers of Mechanical Engineering, 2023, 18(1): 12. https://doi.org/10.1007/s11465-022-0728-9

    Surgical electrodes rely on thermal effect of high-frequency current and are a widely used medical tool for cutting and coagulating biological tissue. However, tissue adhesion on the electrode surface and thermal injury to adjacent tissue are serious problems in surgery that can affect cutting performance. A bionic microstriped structure mimicking a banana leaf was constructed on the electrode via nanosecond laser surface texturing, followed by silanization treatment, to enhance lyophobicity. The effect of initial, simple grid-textured, and bionic electrodes with different wettabilities on tissue adhesion and thermal injury were investigated using horizontal and vertical cutting modes. Results showed that the bionic electrode with high lyophobicity can effectively reduce tissue adhesion mass and thermal injury depth/area compared with the initial electrode. The formation mechanism of adhered tissue was discussed in terms of morphological features, and the potential mechanism for antiadhesion and heat dissipation of the bionic electrode was revealed. Furthermore, we evaluated the influence of groove depth on tissue adhesion and thermal injury and then verified the antiadhesion stability of the bionic electrode. This study demonstrates a promising approach for improving the cutting performance of surgical electrodes.

  • RESEARCH ARTICLE
    Gang SHEN, Jufan ZHANG, David CULLITON, Ruslan MELENTIEV, Fengzhou FANG
    Frontiers of Mechanical Engineering, 2022, 17(2): 26. https://doi.org/10.1007/s11465-022-0682-6

    The tribological performance of artificial joints is regarded as the main factor of the lifespan of implanted prostheses. The relationship between surface roughness and coefficient of friction (COF) under dry and lubricated conditions is studied. Results show that under dry test, friction coefficient is not reduced all the time with a decrease in surface roughness. On the contrary, a threshold of roughness value is observed, and frictional force increases again below this value. This critical value lies between 40 and 100 nm in Sa (roughness). This phenomenon is due to the transfer of friction mechanisms from abrasion to adhesion. Under wet test, COF always decreases with reduction in surface roughness. This result is mainly attributed to the existence of a thin layer of lubricant film that prevents the intimate contact of two articulating surfaces, thus greatly alleviating adhesion friction. Furthermore, surface texturing technology is successful in improving the corresponding tribological performance by decreasing friction force and mitigating surface deterioration. The even-distribution mode of texturing patterns is most suitable for artificial joints. By obtaining the optimal surface roughness and applying texturing technology, the tribological performance of polymer-based bioimplants can be greatly enhanced.