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authoren Fabrication of cobalt–nickel material libraries was performed by electrodeposition in a modified 3D-printed Hull cell using sulfate-based electrolyte baths containing trisodium citrate or glycine as additives. A transition from anomalous to normal co-deposition behavior was observed for different overall applied current densities. Scanning electron microscopy (SEM) images showed needle-shaped crystallites on the sample obtained from citrate solution and a nodular surface morphology for the material library from glycine solution. Non-enzymatic glucose sensing was carried out by flow-type scanning droplet cell microscopy (FT-SDCM) to investigate the electrocatalytic activity for glucose oxidation. Cobalt–nickel material library fabricated by electrodeposition in the presence of trisodium citrate or glycine as additives using a modified 3D-printed Hull cell.

A Co–Cu–Ni thin film material library was fabricated using a modified 3D-printed Hull cell. Rather than previous one by one attempts a combinatorial approach was here not to miss the exact optimum performance composition. An optimum activity at Co-16 at.% Cu-12 at.% Ni for the electrocatalytic glucose oxidation was found by screening along the compositional spread using flow-type scanning droplet cell microscopy (FT-SDCM). Crystallographic properties, surface microstructure and surface topography were investigated along the entire compositional spread using X-ray diffraction (XRD), scanning electron microscopy (SEM) as well as atomic force microscopy (AFM), respectively. The entire compositional spread (Co 40–76 at.%, Cu 0–19 at.% and Ni 11–60 at.%) showed suitability for being used in glucose detection, as determined by cyclic voltammetric measurements. A maximum response for glucose electrooxidation was identified at a Ni content of 12 at.% with a current density value of 21.8 mA cm−2. The performance of a glucose sensor constructed using this identified thin film alloy was evaluated by localised amperometric detection. A linear behaviour was obtained for a wide range of glucose concentrations in the electrolyte solution between 1 mM and 100 mM. Additionally, the identified thin film alloy showed high stability, good electrooxidation reproducibility and high selectivity, thus indicating its suitability for being used as catalyst in glucose detection.

Metal oxide thin films for soft and flexible electronics require low cost, room temperature fabrication, and structuring processes. We here introduce an anodic printing process to realize the essential building blocks of electronic circuitry, including resistors, capacitors, field-effect transistors, diodes, rectifiers, and memristors directly on imperceptible plastic substrates. Largely independent on surface properties, we achieve high-quality, few nanometer thin dielectric and semiconducting films even on rough substrates via localized anodisation of valve metals using a scanning droplet cell microscope. We demonstrate printing-like fabrication of 3D multilayer solid-state capacitors with a record-high areal capacity of 4 µF cm−2. Applicable to the whole class of valve metals and their alloys, our method provides a versatile fabrication technique for the circuits that empower the flexible and stretchable electronics of tomorrow. A simple concept of scanning head-guided anodization is shown to be highly expandable to fabricate various electronic components. A team led by Professor Siegfried Bauer from Johannes Kepler University Linz, Austria develops a universal and patternable printing protocol of anodic oxides for a full range of circuit components for flexible devices. The researchers employ a scanning droplet cell microscope to anodize the pre-deposited thin metal films to form dielectric layers with good control in both lateral dimension and vertical thickness. They demonstrate the versatility of the on-site anodization methods by fabricating oxides-based resistors, diodes, transistors and memristors, and multilayer capacitors with a record-high areal capacity of 4 µF cm−2. The approach is cheap, adaptable, and thus ideal for rapid-prototyping of metal oxides circuits for various applications.

Cobalt–nickel material libraries were electrodeposited in two different types of modified Hull cells. Chloride and sulphate based electrolyte baths, the influence of the overall applied current density, cobalt concentration in the bath and addition of citrate as complexing agent were studied. The experiments suggested a higher cobalt content in the deposits for relatively low overall applied current densities and higher Co2+ concentrations in the electrolyte bath. For the vast majority of the cobalt–nickel material libraries, a transition from anomalous to normal co-deposition behaviour was found as a result of the current density gradient establishing in the Hull cell during electroplating. Further examination was carried out by scanning electron microscopy (SEM), revealing a changing surface morphology within a material library depending on the cobalt content and the current density. X-ray diffraction (XRD) showed separate and mixed face-centred cubic (fcc) and hexagonal close-packed (hcp) crystallographic structures. Cobalt–nickel composition gradient obtained from two different Hull cell modifications including SEM micrographs of the material library deposited in the lying Hull cell.

Two types of nonbreakable, flexible micro-reference electrodes filled with gel-electrolytes were prepared for use in solutions with alkaline and neutral pH. The electrodes are intended for electrochemical measurements, in which chloride-free conditions are important. Due to the flexible, bendable construction of the electrodes, electrochemical experiments at locations difficult to access with common reference electrodes are enabled. Hg|HgO-type electrodes were prepared from amalgamated Au wires, followed by oxidation of the amalgam, which is mounted in a PTFE tube filled with 0.1M NaOH solution immobilized in a PAA-g-PEO gel. The potential of this type of electrode was found to be 0.162 ± 0.002 V (SHE) at room temperature. Cu|CuSO4 electrodes, consisting of a Cu wire immersed in a saturated CuSO4 solution jellied with gelatin, showed a stable open-circuit potential of 0.312 ± 0.001 V (SHE). Further characterization of the electrodes was performed in terms of electrochemical impedance spectroscopy and micro-polarization measurements. As an alternative to the flexible electrodes, rigid electrodes in glass enclosure were fabricated in analogy to the flexible-type electrodes.

Aluminium terbium alloys were prepared by simultaneous thermal evaporation resulting in a thin film library covering a 5 to 25 at.% Tb compositional spread. Synchrotron x-ray diffraction (XRD) proves all of the alloys to be amorphous. Scanning electron microscopy (SEM) measurements reveal the structural changes upon increase in Tb content with the formation of small, Tb-rich segregations right before a drastic change in morphology around 25 at.% Tb. Anodic oxides were formed systematically in cyclic voltammograms using scanning droplet cell microscopy. Coulometric analysis revealed a linear thickness over formation potential behaviour with film formation factors ranging from 1.2 nm V−1 (5 at.% Tb) to 1.6 nm V−1 (25 % Tb). Electrochemical impedance spectroscopy was performed for each incremental oxidation step resulting in a linear relation between inverse capacity and formation potential with dielectric constants ranging from 8 (5 at.% Tb) to 16 (25 at.% Tb).