Theoretical and Experimental Analysis of Surface Roughness and Adhesion Forces of MEMS Surfaces Using a Novel Method for Making a Compound Sputtering Target

Influence of Thin Film Deposition on AFM Cantilever Tips in Adhesion and Young’s Modulus of MEMS Surfaces

Adhesion is a critical factor in microelectromechanical systems (MEMSs) and is influenced by many parameters. In important fields, such as microassembly, an improved understanding of adhesion can result in higher precision. This study examines the influence of deposition of gold and titanium onto the atomic force microscope (AFM) tips in adhesion forces and Young’s modulus, between a few MEMS substrates (silicon, gold, and silver) and the AFM tips. It was found that, except for gold substrate, an AFM tip coated with gold has the highest adhesion force of 42.67 nN for silicon substrates, whereas the titanium-coated AFM tip decreases the force for all the samples. This study suggests that such changes must be taken into account while studying the adhesion force. The final results indicate that utilizing gold substrate with titanium AFM tip led to the lowest adhesion force, which could be useful in adhesion force measurement during microassembly.

Novel electrosprayed enhanced microcapsules with different nanoparticles containing healing agents in a single multicore microcapsule

A novel method was employed to synthesize microcapsules containing both epoxy and hardener healing agents in a single microcapsule using a two-step electrospraying technique. Moreover, the sodium alginate microcapsule shell was enhanced with three types of nanoparticles, including MWCNT, nanoclay, and nanosilica. The surface morphology of fabricated microcapsules was examined using FESEM and AFM images. The TEM and elemental mapping images illustrated that the added nanoparticles into sodium alginate microcapsule shells were dispersed homogeneously. In addition, the mechanical properties of microcapsule shells were obtained using nanoindentation tests. Based on this research, the addition of nanoparticles increased the size and the roughness of microcapsules and improved the elastic modulus and the hardness of microcapsule's outer shells, significantly. For instance, the elastic modulus and the hardness of incorporated microcapsule shells with MWCNT increased by 85.5% and 91.3%, respectively, compared to neat sodium alginate multicore microcapsules, due to intrinsic high strength and high aspect ratio of MWCNT.

Experimental Study of Rheological Behavior of MWCNT-Al2O3/SAE50 Hybrid Nanofluid to Provide the Best Nano-lubrication Conditions

In this study, MWCNT-Al₂O₃ hybrid nanoparticles with a composition ratio of 50:50 in SAE50 base oil are used. This paper aims to describe the rheological behavior of hybrid nanofluid based on temperature, shear rate ([Formula: see text] and volume fraction of nanoparticles ([Formula: see text]) to present an experimental correlation model. Flowmetric methods confirm the non-Newtonian behavior of the hybrid nanofluid. The highest increase and decrease in viscosity ([Formula: see text]) in the studied conditions are measured as 24% and - 17%, respectively. To predict the experimental data, the five-point-three-variable model is used in the response surface methodology with a coefficient of determination of 0.9979. Margin deviation (MOD) of the data is determined to be within the permissible limit of - 4.66% < MOD < 5.25%. Sensitivity analysis shows that with a 10% increase in [Formula: see text] at [Formula: see text] 1%, the highest increase in [Formula: see text] of 34.92% is obtained.