Dataico Albertin

Outline What are the requirements? Why ALD? Protection against corrosion Protection against UV Conclusions

Needs in bioapplications Different devices, like bio-MEMS (sensors, surgery tools…) [1] How foreign bodies interact with the organism [2] Interaction happens on the surface Biocompatibility [1]

Why ALD? Uniformity (hermetic coating) [2] Conformal deposition Great variety of substrates and film materials Good adhesion

Protection against corrosion on stainless steel [3] Temporary contact medical devices (e.g. forceps, kidney dishes…) Biological fluids  NaCl rich  pitting corrosion ALD offers defect free films Reduction of passivation region current density

Two different roughness substrates (AISI 316) 100nm Al 2 O 3 : Al(CH 3 ) 3 precursor 300nm amorphous TiO 2 : TiCl 4 precursor H 2 O as oxidant agent for both Roughness virtually equal after deposition Fig 1: SEM image of Sample A [3] Fig 2: SEM image of Sample B [3]

UV protection: ALD TiO2 on PES [4] PES: heat resistant, mechanically strong polymer Surgical tools, bandages… UV light (sterilization) causes loss of mechanical properties 21nm after 100 cycles Room temperature deposition TDMAT as a precursor Fig 3: difference in color in uncoated PES samples after and before UV exposure [4]

Conclusions ALD is more and more used in medical applications Most versatile in such delicate environment High quality protection films

Questions

References 1. Finch, Oreskovic, Ramadurai, Hermann, George, Mahajari. “Biocompatibility of atomic layer-deposited alumina thin films” Wiley Periodicals, Cianci, Lattanzio, Seguini, Vassanelli, Fanciulli. “Atomic layer deposited TiO2 for implantable brain-chip interfacin devices” Thin Solid Films 520 (2012) Marin, Lanzutti, Guzman, Fedrizzi. “Corrosion protection of AISI 316 stainless steel by ALD alumina/titania nanometric coatings” J. Coat. Technol. Res., 8 (5) , Petrochenko, Scarel, Hyde, Parsons, Skoog, Zhang, Goering, Narayan. “Prevention of UV-induced Surface Damage and Cytotoxicity of Polyethersulfone Using Atomic Layer Deposition (ALD) Titanium Dioxide” JOM, Vol. 65, No. 4, 2013