Narrow Results

Porous NiTi shape memory alloy (SMA) with 48% porosity and an average pore size of 50–800 μm was synthesized by capsule-free hot isostatic pressing (CF-HIP). To enhance the surface bioactivity, the porous NiTi SMA was subjected to H₂O₂ and subsequent NaOH treatment. Scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy analyses revealed that a porous sodium titanate (Na₂TiO₃) film had formed on the surface of the porous NiTi SMA. An apatite layer was deposited on this film after immersion in simulated body fluid at 37°C, while no apatite could be found on the surface of the untreated porous NiTi SMA. The formation of the apatite layer infers that the bioactivity of the porous NiTi SMA may be enhanced by surface chemical treatment, which is favorable for its application as bone implants.

Liquid-infused porous surfaces inspired by Nepenthes pitcher plant were fabricated on polyurethane. Five different micro-structures, including pillar (PIL), Sharklet${}^{\circledR }$ (SHK), continuous discrete ridge (DIR), hole (HOL) and networking (NET), were fabricated by soft lithography. Effects of micro-structural geometry on lubricant infiltration capability were investigated by infiltration the micro-structures with two lubricants of different viscosity, Krytox-103 ($\eta$: 0.131 $\mathrm{\text{Pa}}\cdot \mathrm{\text{s}}$) and Krytox-105 ($\eta :0.737\mathrm{\text{Pa}}\cdot \mathrm{\text{s}}$). The lubricant infiltration and retention capability were determined using a confocal laser scanning micro-scopy, and properties of the infused surfaces were evaluated by measuring the speed of water droplet motion at various tilting angles. The results revealed that, for the 80$\mu$m-high micro-structures, infiltration with a less viscous Krytox-103 resulted in more complete infiltration and retention, particularly for the PIL micro-structure. The infused surface exhibited a slippery behavior signified by low sliding angle and good anti-adhesion against chlorophyll fluid and milk yogurt. The lubricant retention capability was significantly reduced for the 7$\mu$m-high micro-structures due to lower aspect ratio and low capillary force. In this case, the PIL infused with a more viscous Krytox-105 provided a slippery surface.