Flexible and soft bioelectronics display conflicting demands on miniaturization, compliance, and reliability. Here, the authors investigate the design and performance of thin encapsulation multilayers against hermeticity and mechanical integrity. Partially cracked organic/inorganic multilayer coatings are demonstrated to display surprisingly year‐long hermetic lifetime under demanding mechanical and environmental loading. The thin hermetic encapsulation is grown in a single process chamber as a continuous multilayer with dyads of atomic layer deposited (ALD) Al2O3‐TiO2 and chemical vapor deposited Parylene C films with strong interlayer adhesion. Upon tensile loading, tortuous diffusion pathways defined along channel cracks in the ALD oxide films and through tough Parylene films efficiently postpone the hermeticity failure of the partially cracked coating. The authors assessed the coating performance against prolonged exposure to biomimetic physiological conditions using coated magnesium films, platinum interdigitated electrodes, and optoelectronic devices prepared on stretchable substrates. Designed extension of the lifetime preventing direct failures reduces from over 5 years yet tolerates the lifetime of 3 years even with the presence of critical damage, while others will directly fail less than two months at 37 °C. This strategy should accelerate progress on thin hermetic packaging for miniaturized and compliant implantable electronics.
In this work, a multi-sensor chip for the investigation of the sensing properties of different types of metal oxides towards hydrogen peroxide in the ppm range is presented. The fabrication process and physical characterization of the multisensor chip are described. Pure SnO 2 and WO 3 as well as Pdand Pt-doped SnO 2 films are characterized in terms of their sensitivity to H 2 O 2 . The sensing films have been prepared by drop-coating of water-dispensed nano-powders. A physical characterization, including scanning electron microscopy and X-ray diffraction analysis of the deposited metal-oxide films, was done. From the measurements in hydrogen peroxide atmosphere, it could be shown, that all of the tested metal oxide films are suitable for the detection of H 2 O 2 in the ppm range. The highest sensitivity and reproducibility was achieved using Pt-doped SnO 2 .Calibration plot of a SnO 2 , WO 3 , Pt-, and Pd-doped SnO 2 gas sensor for H 2 O 2 concentrations in the ppm range.
Transparent conductive metal oxides are interesting materials for various optoelectronic applications including solar cells and flat panel displays. This study focuses on the in situ deposition of aluminum-doped zinc oxide (AZO) thin layers on c-axis oriented sapphire substrates by dc sputtering and on the structural and electrical characterization. The films have a typical thickness of 90 nm and a roughness of 10 nm root mean square. An Al/Zn ratio of 2.4 at% Al was determined by X-ray photoelectron spectroscopy. X-ray diffraction shows a preferential growth in the (0002) c-axis direction. Films have an average transparency of 90% in the visible-light spectrum, a room-temperature resistivity of 3.7 Â 10 À3 V cm and a carrier mobility of 6.7 cm 2 V À1 s À1 .
Plasma-enhanced chemical vapor deposition (PECVD) was used to deposit SiO x thin films of varying thicknesses on parylene C substrates, using hexamethyldisiloxane (HMDSO) as a precursor. The microstructure of SiO x coatings was analyzed using X-ray photoemission spectroscopy (XPS), nanoindentation, and spectroscopic ellipsometry. The composition ranged from oxygen-rich oxides with large silanol OH content to hybrid oxides with larger organic content, while refractive index varied from 1.45 to 1.5 depending on the specimen. Reduced moduli of coatings obtained by nanoindentation varied between 15 and 59 GPa and could be correlated with permeability to oxygen and water vapor through the existence of porosity in a broader sense. It can be concluded that the barrier properties are the result of a complex interplay of microstructural features, with porosity, silanol, and carbon content playing important roles in the final thin film properties.
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