Characterization of the effect of fractal micro-protrusion and heat on the wettability behavior on chips in medical MEMS

Abstract

Interfacial wettability, a fundamental property of solid surfaces in the medical field, is known to be affected by surface microstructure and temperature. This research aims to examine the influence of temperature on wettability by creating two distinct types of fractal single-stage microstructures on medical silicon wafers, utilizing the combined features of single-stage microstructure and fractal micro-nano structure. The experimental findings indicate that the area fraction and roughness of the fractal microstructure exhibit variations based on the specific fractal dimension employed. The hydrophobicity of the Sierpinski triangle fractal microstructure surpasses that of other tested microstructures under the same machining accuracy, which can increase the hydrophobicity of the chip surface by 47.9% on average. Furthermore, the hydrophobicity of the Sierpinski triangle fractal microstructure is found to be 13.1% higher than that of the Sierpinski carpet fractal microstructure, despite the temperature stability of the latter is 35% higher. When compared to a uniform micropillar structure with identical parameters, the Sierpinski carpet fractal microstructure demonstrates superior hydrophobicity, while the Sierpinski triangle fractal microstructure exhibits lower hydrophobicity. These findings suggest that the incorporation of fractal microstructures significantly influences the wettability of medical chips under different temperatures, which holds promise for its application in medical MEMS.