Faculty Publications

Now showing 1 - 4 of 4

Coating technologies for copper based antimicrobial active surfaces: A perspective review
(MDPI AG, 2021) Bharadishettar, N.; Bhat K, U.; Bhat Panemangalore, D.B.
Microbial contamination of medical devices and treatment rooms leads to several detrimental hospital and device‐associated infections. Antimicrobial copper coatings are a new approach to control healthcare‐associated infections (HAI’s). This review paper focuses on the efficient methods for depositing highly adherent copper‐based antimicrobial coatings onto a variety of metal surfaces. Antimicrobial properties of the copper coatings produced by various deposition methods including thermal spray technique, electrodeposition, electroless plating, chemical vapor deposition (CVD), physical vapor deposition (PVD), and sputtering techniques are compared. The coating produced using different processes did not produce similar properties. Also, process parameters often could be varied for any given coating process to impart a change in structure, topography, wettability, hardness, surface roughness, and adhesion strength. In turn, all of them affect antimicrobial activity. Fundamental concepts of the coating process are described in detail by highlighting the influence of process parameters to increase antimicrobial activity. The strategies for developing antimicrobial surfaces could help in understanding the mechanism of killing the microbes. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
Degradation response and bioactivity assessment of antimicrobial copper coatings in simulated hand sweat environment
(Elsevier B.V., 2022) Bharadishettar, N.; Udaya Bhat, K.
The antimicrobial copper coatings were deposited on AISI 304 stainless steel (SS) using electrodeposition technique for touch surface applications. Electrodeposition was performed using a non-cyanide electrolyte, with varying copper concentrations. The copper coatings were investigated for their microstructure, in vitro degradation in the simulated hand sweat environment, and antimicrobial activity in an agar medium. It is noted that all the coatings have nanostructures in their microstructure. The microstructure of the coatings along with the contact period with the bacteria affects the antimicrobial activity measured against Escherichia coli and Staphylococcus aureus. The nanostructured morphology has resulted in an increased surface area with enhanced copper toxicity. The degradation behavior of coatings in the simulated hand sweat solution was further probed using potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS). © 2022 Elsevier B.V.
Effect of acid pickling treatment of stainless steel substrate on adhesion strength of electrodeposited copper coatings using non-cyanide electrolyte
(Elsevier Ltd, 2023) Bharadishettar, N.; Udaya Bhat, K.
In recent years, copper-based antimicrobial coatings have gained popularity in healthcare and public recreation facilities. The morphology, topography, and adhesion strength are decisive properties for copper coatings to have long-term antimicrobial effectiveness in hospital environments. This work explores the effect of multistage acid pickling treatment of AISI 304 stainless steel substrate on the adhesion strength of the copper coating. The copper coating was obtained by electrodeposition using an alkaline non-cyanide electrolyte. After the fourth stage of acid pickling, the copper coating had an excellent adhesion strength, up to 9 MPa. Glow discharge optical emission spectroscopy (GDOES) examination revealed no oxide scales or other contaminants on the SS surface after the fourth (final) stage of acid pickling. Using a non-contact optical profilometer, it was observed that the roughness of the substrate increased with each stage of the pickling treatment. The surface topography analysis confirms the increased density of the interlocking sites, which favors the adhesion of the coating. On the other hand, the microstructure of the copper coating showed a cauliflower-like morphology with an average nodule size of 28 nm. Transmission electron microscopy confirmed that the coatings have nano-scaled crystallites with internal twins inside the grains of copper coatings. © 2023 Elsevier Ltd
Development of adherent antimicrobial copper coatings on stainless steel for healthcare applications
(Springer, 2023) Bharadishettar, N.; Bhat, K.U.; Bhat, K.S.
Copper coatings were fabricated using an environmentally sustainable non-cyanide electrodeposition technique. By following four-stage acid pickling treatment of the substrate and optimum parameters during electrodeposition, adhesion strength up to 9 MPa was obtained. Four different copper coatings were fabricated by varying CuSO4. 5H2O concentration in an electrolyte (10, 15, 30, and 45 g/L) to understand nucleation and growth mechanism and surface texture evolution. Nano-nodular morphology of the deposited copper marks a significant feature. It increases the fraction of grain boundaries in it. The grazing incidence X-ray diffraction analysis revealed the preferred orientation along the (111) plane with the presence of residual compressive stresses (in the range of 24.90–273.92 MPa). Surface texture studies indicated that the coating had an abundance of nano-scaled protruding structures with surface roughness’s Sa in the range of 2.507–1.674 µm (Ra in a range of 1.714–1.235 µm). It offers 3D contact with microbes. The developed coating had increased hardness (41.93%), scratch resistance (58.77%), and 9 MPa adhesion strength with the substrate. Initially, copper coatings had hydrophobicity against water (initial contact angle in the range of 134–139°). The extent of hydrophobicity decreased with exposure time. The developed coatings exhibited significant antimicrobial activity. Antimicrobial studies using the cell viability technique indicated that the coating exhibits toxicity against Escherichia coli (ATCC25922) and Staphylococcus aureus (MCC2408) microbes. 100% reduction of the survival of microbes is observed after 4 h of exposure. Graphical Abstract: [Figure not available: see fulltext.]. © 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.

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