Self-assembly methods combined with standard top-down approaches are demonstrated to be suitable for fabricating three-dimensional ultracompact hybrid organic/inorganic electronic devices based on rolled-up nanomembranes. Capacitors that are self-wound and manufactured in parallel are almost 2 orders of magnitude smaller than their planar counterparts and exhibit capacitances per footprint area of around 200 microF/cm(2). This value significantly exceeds that which was previously reported for metal-insulator-metal capacitors based on Al(2)O(3), and the obtained specific energy (approximately 0.55 Wh/kg) would allow their usage as ultracompact supercapacitors. By incorporating organic monolayers into the inorganic nanomembrane structure we can precisely control the electronic characteristics of the devices. The adaptation of the process for creating ultracompact batteries, coils and transformers is an attractive opportunity for reducing the size of energy storage elements, filters, and signal converters. These devices can be employed as implantable electronic circuits or new approaches for energy-harvesting applications. Furthermore, the incorporation of functional organic molecules gives rise to novel devices with almost limitless chemical and biological functionalities.

Transparent oxide rolled-up microtube arrays were constructed on Si substrates by the deposition of a pre-stressed oxide layer on a patterned photoresist sacrificial layer and the subsequent removal of this sacrificial layer. These microtubes as well as their arrays can be well positioned onto a chip for further applications, while their dimensions (e.g. length, diameter and wall thickness) are controlled by tunable parameters of the fabrication process. Due to the unique tubular structure and optical transparency, such rolled-up microtubes can serve as well-defined two-dimensionally (2D) confined cell culture scaffolds. In our experiments, yeast cells exhibit different growth behaviors (i.e. their arrangement) in microtubes with varied diameters. In an extremely small microtube the yeast cell becomes highly elongated during growth but still survives. Detailed investigations on the behavior of individual yeast cells in a single microtube are carried out in situ to elucidate the mechanical interaction between microtubes and the 2D confined cells. The confinement of tubular channels causes the rotation of cell pairs, which is more pronounced in smaller microtubes, leading to different cellular assemblies. Our work demonstrates good capability of rolled-up microtubes for manipulating individual and definite cells, which promises high potential in lab-on-a-chip applications, for example as a bio-analytic system for individual cells if integrated with sensor functionalities.

We fabricate inorganic thin film transistors with bending radii of less than 5 μm maintaining their high electronic performance with on-off ratios of more than 10(5) and subthreshold swings of 160 mV/dec. The fabrication technology relies on the roll-up of highly strained semiconducting nanomembranes, which compacts planar transistors into three-dimensional tubular architectures opening intriguing potential for microfluidic applications. Our technique probes the ultimate limit for the bending radius of high performance thin film transistors.

Articles you may be interested inAlInP-based rolled-up microtube resonators with colloidal nanocrystals operating in the visible spectral range Appl.

Bulky organic semiconductors have been widely applied on a variety of devices including transistors, sensors, and organic light-emitting diodes. Recently, the capability of producing stable ultrathin organic semiconductor-based junctions has opened the possibility of a variety of novel device concepts, including highspeed organic transistors, organic spin valves, and biosensors. In such context, the investigation of the charge transport mechanisms across ultrathin organic semiconductors is the key for the engineering of emerging organic-based technologies. Here, the charge transport mechanisms across heterojunctions based on physisorbed ultrathin copper phthalocyanine on gold are precisely determined and controlled over a wide range of temperatures and electric fields. We observe that the macroscopic electrical characteristics of Au/CuPc/Au heterojunctions are similar to what has been reported for chemisorbed molecular junctions. For instance, the transition from thermally activated transport to tunneling is verified regardless of the nature of the molecule-contact bonding. The Au/CuPc/Au heterojunction transport is dominated by charge localization sites at high temperatures and, upon cooling, a continuous transition from direct tunneling, via resonant tunneling, to field emission takes place by increasing the voltage bias. Such a continuous transition has not been reported for a hybrid metal/organic heterojunction yet. We have also determined the dielectric constant of the CuPc molecular layer via transport measurements, which allowed us to infer the possible molecule arrangements between the electrodes.

In this work, we combine self-assembly and top-down methods to create hybrid junctions consisting of single organic molecular monolayers sandwiched between metal and/or single-crystalline semiconductor nanomembrane based electrodes. The fabrication process is fully integrative and produces a yield loss of less than 5% on-chip. The nanomembrane-based electrodes guarantee a soft yet robust contact to the molecules where the presence of pinholes and other defects becomes almost irrelevant. We also pioneer the fabrication and characterization of semiconductor/molecule/semiconductor tunneling heterojunctions which exhibit a double transition from direct tunneling to field emission and back to direct tunneling, a phenomenon which has not been reported previously.

The wrinkling of thin films on substrate surfaces is a wellknown phenomenon, and has been studied in different material systems in great detail for several decades. [1][2][3][4][5][6][7][8][9][10][11] While several potential applications of wrinkles have been put forward, such as applications in force spectroscopy in cells, [1] optical devices, [3] metrology methods, [9] and flexible electronics, [11] the use of wrinkles as complex nanochannel networks on a substrate surface to study nanofluidics [12][13][14] or to herald applications in bionanotechnology [15][16][17] seems an intriguing and almost obvious idea. Recently, the employment of folded thin films [18] with wrinkles that run perpendicular to the main fold has been suggested for realizing complex nanochannel systems, [4] but thus far fluid flow through such wrinkles has not been reported.Here, we describe a technology that exploits the deterministic wrinkling and subsequent bond-back of a semiconductor layer to create well-defined and versatile nanochannel networks. The technology is termed "release and bond-back of layers" (REBOLA), and consists of the partial release, wrinkling, and bond-back of a compressively strained functional layer on a substrate surface. Linear and circular nanochannel networks, both of which consist of a main channel and several perpendicularly oriented branch channels, were fabricated by REBOLA. In these networks the periodicity and the positions of the branch channels could be tuned and controlled by changing the width of the partially released layers and by applying appropriate lithographic techniques. To elucidate the usefulness of REBOLA, we demonstrate nanofluidic transport as well as femtoliter filling and emptying of individual wrinkles on a standard semiconductor substrate.

The fabrication, characterization, and optimization of large area rolled-up ultracompact nanomembrane-based capacitor arrays is demonstrated by combining bottom-up and top-down fabrication methods. The scalability of the process is tested on a 4-inch wafer platform where 1600 devices are manufactured in parallel. By using a hybrid dielectric layer consisting of HfO 2 and TiO 2 incorporated into an Al 2 O 3 matrix, rolled-up ultracompact capacitors can have their capacitance per footprint area increased by over two orders of magnitude. Their electrical properties can be precisely controlled by adjusting the oxide composition. Furthermore, the rolling of large-area nanomembranebased structures naturally results in a substantial decrease of the occupied footprint area. Such electrostatic rolled-up ultracompact energy-storage elements have a large potential in powering various autonomous microsystems.