With the recent expansion of additive manufacturing (AM) in industries, there is an intense need to improve the surface quality of AM parts. A functional surface with extreme wettability would explore the application of AM in medical implants and microfluid. In this research, we propose to superimpose the femtosecond (fs) laser induced period surface structures (LIPSS) in the nanoscale onto AM part surfaces with the micro structures that are fabricated in the AM process. A hierarchical structure that has a similar morphology to a lotus leaf surface is obtained by combining the advantages of liquid assisting fs laser processing and AM. A water contact angle (WCA) of 150° is suggested so that a super hydrophobic surface is achieved. The scanning electron microscopy (SEM) images and X-ray photoelectron spectroscopy (XPS) analysis indicate that both hierarchical structures and higher carbon content in the laser processed area are responsible for the super hydrophobicity.

Additive manufacturing (AM) has become more prominent in leading industries. Recently, there have been intense efforts to achieve a fully functional 3D structural electronic device by integrating conductive structures into AM parts. Here, we introduce a simple approach to creating a conductive layer on a polymer AM part by CO₂ laser processing. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy were employed to analyze laser-induced modifications in surface morphology and surface chemistry. The results suggest that conductive porous graphene was obtained from the AM-produced carbon precursor after the CO₂ laser scanning. At a laser power of 4.5 W, the lowest sheet resistance of 15.9 Ω/sq was obtained, indicating the excellent electrical conductivity of the laser-induced graphene (LIG). The conductive graphene on the AM parts could serve as an electrical interconnection and shows a potential for the manufacturing of electronics components. An interdigital electrode capacitor was written on the AM parts to demonstrate the capability of LIG. Cyclic voltammetry, galvanostatic charge-discharge, and cyclability testing demonstrated good electrochemical performance of the LIG capacitor. These findings may create opportunities for the integration of laser direct writing electronic and additive manufacturing.

The integration of surface-enhanced Raman scattering (SERS) and surface-enhanced fluorescence (SEF) has attracted increasing interest and is highly probable to improve the sensitivity and reproducibility of spectroscopic investigations in biomedical fields. In this work, dual-mode SERS and SEF hierarchical structures have been developed on a single bio-metallic substrate. The hierarchical structure was composed of micro-grooves, nano-particles, and nano-ripples. The crystal violet was selected as reporter molecule and both the intensity of Raman and fluorescence signals were enhanced because of the dual-mode SERS−SEF phenomena with enhancement factors (EFs) of 7.85 × 10⁵ and 14.32, respectively. The Raman and fluorescence signals also exhibited good uniformity with the relative standard deviation value of 2.46% and 5.15%, respectively. Moreover, the substrate exhibited high sensitivity with the limits of detection (LOD) as low as 1 × 10⁻¹¹ mol/L using Raman spectroscopy and 1 × 10⁻¹⁰ mol/L by fluorescence spectroscopy. The combined effect of surface plasmon resonance and “hot spots” induced by the hierarchical laser induced periodical surface structures (LIPSS) was mainly contributed to the enhancement of Raman and fluorescence signal. We propose that the integration of SERS and SEF in a single bio-metallic substrate is promising to improve the sensitivity and reproducibility of detection in biomedical investigations.