Transparent and flexible, nanostructured and mediatorless glucose/oxygen enzymatic fuel cells

Here we detail transparent, flexible, nanostructured, membrane-less and mediator-free glucose/oxygen enzymatic fuel cells, which can be reproducibly fabricated with industrial scale throughput. The electrodes were built on a biocompatible flexible polymer, while nanoimprint lithography was used for their nanostructuring. The electrodes were covered with gold, their surfaces were visualised using scanning electron and atomic force microscopies, and they were also studied spectrophotometrically and electrochemically. The enzymatic fuel cells were fabricated following our previous reports on membrane-less and mediator-free biodevices in which cellobiose dehydrogenase and bilirubin oxidase were used as anodic and cathodic biocatalysts, respectively. The following average characteristics of transparent and flexible biodevices operating in glucose and chloride containing neutral buffers were registered: 0.63 V open-circuit voltage, and 0.6 mu W cm(-2) maximal power density at a cell voltage of 0.35 V. A transparent and flexible enzymatic fuel cell could still deliver at least 0.5 mu W cm(-2) after 12 h of continuous operation. Thus, such biodevices can potentially be used as self-powered biosensors or electric power sources for smart electronic contact lenses. (C) 2015 Elsevier B.V. All rights reserved

Biofuel cell based on microscale nanostructured electrodes with inductive coupling to rat brain neurons.

Miniature, self-contained biodevices powered by biofuel cells may enable a new generation of implantable, wireless, minimally invasive neural interfaces for neurophysiological in vivo studies and for clinical applications. Here we report on the fabrication of a direct electron transfer based glucose/oxygen enzymatic fuel cell (EFC) from genuinely three-dimensional (3D) nanostructured microscale gold electrodes, modified with suitable biocatalysts. We show that the process underlying the simple fabrication method of 3D nanostructured electrodes is based on an electrochemically driven transformation of physically deposited gold nanoparticles. We experimentally demonstrate that mediator-, cofactor-, and membrane-less EFCs do operate in cerebrospinal fluid and in the brain of a rat, producing amounts of electrical power sufficient to drive a self-contained biodevice, viz. 7 μW cm(-2) in vitro and 2 μW cm(-2) in vivo at an operating voltage of 0.4 V. Last but not least, we also demonstrate an inductive coupling between 3D nanobioelectrodes and living neurons

Recommended reading list of early publications on atomic layer deposition-Outcome of the "Virtual Project on the History of ALD"

Atomic layer deposition (ALD), a gas-phase thin film deposition technique based on repeated, self-terminating gas-solid reactions, has become the method of choice in semiconductor manufacturing and many other technological areas for depositing thin conformal inorganic material layers for various applications. ALD has been discovered and developed independently, at least twice, under different names: atomic layer epitaxy (ALE) and molecular layering. ALE, dating back to 1974 in Finland, has been commonly known as the origin of ALD, while work done since the 1960s in the Soviet Union under the name "molecular layering" (and sometimes other names) has remained much less known. The virtual project on the history of ALD (VPHA) is a volunteer-based effort with open participation, set up to make the early days of ALD more transparent. In VPHA, started in July 2013, the target is to list, read and comment on all early ALD academic and patent literature up to 1986. VPHA has resulted in two essays and several presentations at international conferences. This paper, based on a poster presentation at the 16th International Conference on Atomic Layer Deposition in Dublin, Ireland, 2016, presents a recommended reading list of early ALD publications, created collectively by the VPHA participants through voting. The list contains 22 publications from Finland, Japan, Soviet Union, United Kingdom, and United States. Up to now, a balanced overview regarding the early history of ALD has been missing; the current list is an attempt to remedy this deficiency. (C) 2016 Author(s).Peer reviewe

Technology and studies of electron transport in InAs nanowire junctions

The topic of this thesis is technology and experimental studies of electron transport in Indium Arsenide (InAs) nanowires and InAs nanowire junctions. The aim of this work has been fabrication of nanoelectronic devices which have possibilities for future nanoelectronics. The first chapter gives an introduction to modern electronics and some important concepts. The second chapter presents an overview of electron transport in three-terminal conductor junctions. The third chapter introduces the InAs self-forming nanowires. The paper attached to the thesis deals with the technology of the formation of electrical contacts to InAs nanowires. The electrical properties of the three-terminal nanowire junction devices and the device applications are shown and discussed in the manuscript attached to the thesis

Self-Charging Electrochemical Biocapacitor

Two-in-one: A biological supercapacitor—a combination of an electrochemical capacitor and an enzymatic fuel cell—is presented. Both the capacitor and the biofuel cell are built from nanomaterials, namely, polyaniline/carbon nanotube composites and redox enzyme/gold nanoparticle assemblies. The biosupercapacitor is self-charging, membrane- and mediator-les

Assembling ferromagnetic single-electron transistors by atomic force microscopy

We demonstrate the assembly of nanoscale ferromagnetic single-electron transistors using atomic force microscopy for imaging as well as for nanoscale manipulation. A single 30 nm Au disc, forming the central island of the transistor, is manipulated with angstrom precision into the gap between a plasma-oxidized Ni source and drain electrodes. The tunnel resistances can be tuned in real time during the device fabrication by repositioning the Au disc. Transport measurements reveal long-term stable single-electron transistor characteristics at 4.2 K. The well-controlled devices with very small central islands facilitate future in-depth studies of the interplay between Coulomb blockade, spin-dependent tunnelling and spin accumulation in ferromagnetic single-electron transistors at elevated temperatures

Assembling Ferromagnetic Single-electron Transistors with Atomic Force Microscopy

Ferromagnetic Single Electron Transistors (F-SETs) comprise ferromagnetic electrodes connected to a ferromagnetic- or non-magnetic central island via tunnel barriers. These devices are important for studies of spin-transport physics in confined structures. Here we describe the development of a novel type of AFM-assembled nano-scale F-SETs suitable for spin-transport investigations at temperatures above 4.2 K. The ingenious fabrication technique means that their electrical characteristics can be tuned in real-time during the fabrication sequence by re-positioning the central island with Ångström precision

Properties of electrical contacts to filamentary nanocrystals

We investigated properties of electrical contacts to filamentary nanocrystals based on InAs, synthesized by chemical-beam epitaxy. Robust, low resistive Ohmic contacts were manufactured to InAs segment of filamentary nanocrystals both directly and indirectly, through a catalytic particle at the top of nanocrystals. Current-voltage characteristics and degradation characteristics of devices based on InAs nanocrystals with electrical contacts are presented. It was determined, that properties of electrical contacts to nanocrystals can be improved by excluding natural oxide layer on the interface between metal and nanocrystal material

Concept for assembling individual nanostructure-based components into complex devices

Minute electronic (bio) devices will likely play an increasingly important role in everyday life and beyond, as overall device size often limits device functionality and applicability, a factor especially critical for brain implants. Recent progress in micro-and nanoelectronics has enabled the production of nanoscale electronic components; however, overall device size is often defined by technical and technological limitations, in particular, the ability to combine heterogeneous components made using incompatible processes on different substrates. Here, the authors suggest and evaluate a concept and approach aimed at the direct three-dimensional assembly of individual nanoscale-based components into complex devices for brain implants. They demonstrate this assembly possibility via the transfer of free-standing GaP nanowires, as well as test devices made of gold film which exhibit good quality electrical contacts. The key features essential for such a functional assembly process are discussed. The authors expect this approach to be generic and to enable the development of complex minute electronic (bio) devices based on nanoscale components. The proposed type of assembly may be especially beneficial for devices with strict size constraints, such as implantable neural interfaces. (C) 2015 American Vacuum Society