Laser-patterned carbon coatings on flexible and optically transparent plastic substrates for advanced biomedical sensing and implant applications

Medical grade polyethylene-based skeletal implants exhibit osteo-disintegration, erosion, and modest hemocompatibility. Herein, we report on the fabrication of highly adherent undoped and Si-containing DLC (Si-DLC) coatings for biomedical implant applications by utilizing plasma and laser-based processing techniques on thermally sensitive polyethylene (PE) substrates. Scratch testing reveals a strong interfacial shear strength of 620 MPa for DLC coatings deposited on PE. A contact stress of similar to 32 MPa induced cracking of the DLC thin film. The Si-DLC films demonstrated a higher critical failure load and less cracking compared to undoped DLC films. The contact angle for PE increased from 90 degrees to 110 degrees when it was coated with the Si-DLC thin film. A high optical bandgap of 2.5 eV was calculated for the 21 at% Si-DLC thin films. Pulsed laser annealing (PLA) of Si-DLC films at 0.3 J cm(-2) increased the amount of sp(2) bonded carbon, resulting in an improvement in lubricity, hydrophobicity, and electrical conductivity properties. In addition, the laser patterned pristine DLC films showed the formation of reduced graphene oxide, which possessed sizeable properties for wearable electronics and biosensing applications (R-s = 0.6 k omega (-1)). This study indicates that PLA is a useful technique for modifying the properties of DLC thin films on flexible polymeric substrates for state-of-the-art biomedical and electronic sensing applications.

Automated summary

This study reports on the fabrication of highly adherent undoped and Si-containing DLC coatings on polyethylene substrates and explores their properties. The results show that Si-DLC coatings have higher interfacial shear strength and less cracking, improve the wettability of polyethylene, and have a higher optical bandgap. In addition, pulsed laser annealing can improve the lubricity, hydrophobicity, and electrical conductivity properties of the coatings, and can also form reduced graphene oxide on DLC thin films.