Eumelanin is a ubiquitous pigment in the human body, animals, and plants, with potential for bioelectronic applications because of its unique set of physical and chemical properties, including strong UV‐vis absorption, mixed ionic/electronic conduction, free radical scavenging and anti‐oxidant properties. Herein, a detailed investigation is reported of eumelanin thin films grown on substrates patterned with gold electrodes as a model system for device integration, using electrical measurements, atomic force microscopy, scanning electron microscopy, fluorescence microscopy, and time‐of‐flight secondary ion mass spectroscopy. Under prolonged electrical biasing in humid air, one can observe gold dissolution and formation of gold‐eumelanin nanoaggregates, the assembly of which leads to the formation of dendrites forming conductive pathways between the electrodes. Based on results collected with eumelanins from different sources, a mechanism is proposed for the formation of the nanoaggregates and dendrites, taking into account the metal binding properties of eumelanin. The surprising interaction between eumelanin and gold points to new opportunities for the fabrication of eumelanin‐gold nanostructures and biocompatible memory devices and should be taken into account in the design of devices based on eumelanin thin films.

Carbon nanotubes (CNTs) are produced using a 100 kW dc non-transferred plasma torch and C2Cl4 as the carbon precursor. Catalytic metallic nanoparticles are generated in situ using the tungsten metal vapours emitted by the electrode erosion process. Large quantities of multi-walled carbon nanotubes (MWNTs) and spherical (onion-like) carbon structures are observed under FE-SEM and TEM. Preliminary results are given here on the effect of the type and pressure of the gas in the reactor on the zone of CNT nucleation. A large amount of CNTs, over 50 µm in length, is observed to grow within the torch nozzle at 0.26 atm pressure in helium and argon. Increasing the pressure to 0.66 atm in both gases has the effect of pushing the CNT production downstream in the gas phase within the main reactor.

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, hydrated thin films of the biomolecule eumelanin are contacted with Au electrodes. Prolonged biasing of these films by C. Santato and co‐workers leads to the growth of Au–eumelanin dendrites, as shown. These structures form upon application of electrical biases as low as 0.6 V and result in a sudden resistive change of the sample upon bridging the interelectrode region. This phenomenon, possibly related to the metal chelation properties of eumelanin, has to be considered in the design of eumelaninbased bioelectronic devices and can potentially be exploited for biocompatible memory devices.

Single splats of commercially pure (CP) Ti are deposited onto sapphire by cold spray under two spray conditions to achieve different in-flight powder velocities. The powders used have two morphologies: spherical powder (SP), manufactured by plasma gas atomization and irregular powder (IP), manufactured by the Armstrong process, with a coral-like morphology. The adhesion strength of the single splats is measured by splat adhesion testing. By use of a specialized in situ scratch tester, interface failure during splat adhesion testing is observed through the sapphire substrate. Particle velocity does not significantly influence the adhesion strength and failure mechanism of SP splats. After deposition, the SP splat has an interface pore in its center which acts as an initiation site for crack propagation during splat adhesion testing. After failure, a well bonded portion of Ti remains on the substrate in the shape of a ring. IP splats deposited at low velocity show similar, well adhering, rings on the surface in localized locations scattered throughout the interface. An increase in velocity for IP splats led to an increase in adhesion strength and a nearly continuous well adhering interface. The behaviour of IP splats is understood by electron channelling contrast images of cross-sections where low velocities resulted in little change in microstructure while high velocities led to a highly deformed microstructure at the interface.