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To meet the dimensional requirements for bioelectronic medicine, new packaging solutions are needed that could enable small, light-weight and flexible implants. For protecting the implantable electronics against biofluids, recently various atomic layer deposited (ALD) coatings have been proposed with high barrier properties. Before implantation, however, the protective coating should be evaluated for any defects which could otherwise lead to leakage and device failure. In these cases, the conventional helium leak test method can no longer be used due to the millimeter size of the implant. Therefore, an in-situ sensing platform is needed that could evaluate the coating and justify the implantation of the final device. In this work, we explore the possibility of using the CMOS bulk for such a platform. Towards this aim, as a proof of concept, test chips were made in a standard 6-metal 0.18 µm CMOS process and for the connection to the bulk, a p+ diffusion was used. A group of samples was then coated with an ALD multilayer. For coating evaluation, off-chip DC current leakage and impedance measurements were carried out in saline between the CMOS bulk and a platinum reference electrode. Results were compared between non-coated and coated chips that clearly demonstrated the potential of using the bulk as a sensing platform for coating evaluations. This novel approach could pave the way towards an all integrated in-situ hermeticity test, currently missing in mm-size implants.

H2020-ICT-2014-1 ERC-CoG-2014 CapTherPV, 647596 Aluminium doped zinc oxide (AZO) films were grown by Atomic Layer Deposition (ALD) on yellow Kapton and transparent Kapton (type CS) substrates for large area flexible transparent thermoelectric applications, which performance relies on the thermoelectric properties of the transparent AZO films. Therefore, their adhesion to Kapton, environmental and bending stability were accessed. Plasma treatment on Kapton substrates improved films adhesion, reduced cracks formation, and enhanced electrical resistance stability over time, of importance for long term thermoelectric applications in external environment. While exposure to UV light intensity caused the films electrical resistance to vary, and therefore their maximum power density outputs (0.3–0.4 mW/cm3) for a constant temperature difference (∼10 °C), humidity exposure and consecutive bending up to a curvature radius above the critical one (∼18 mm) not. Testing whether the films can benefit from encapsulation revealed that this can provide extra bending stability and prevent contacts deterioration in the long term. publishersversion published

Atomic layer deposition (ALD) is widely in use for depositing a variety of materials, such as metal oxides, metal nitrides and metals, in a conformal and defect-free form at low temperatures on high aspect-ratio substrates. These advantages make ALD uniquely powerful method for applications where sensitive substrate materials combine with extreme demands on coating quality and temperature/chemical resistance, such as those often seen in the medical applications.