L. Couraud

Bio: L. Couraud is an academic researcher from Centre national de la recherche scientifique. The author has contributed to research in topics: High impedance & Noise (electronics). The author has an hindex of 9, co-authored 21 publications receiving 1234 citations.

Electro-osmotic propulsion of helical nanobelt swimmers

Abstract: Micro and nanoscale mobile agents capable of self-propulsion in low Reynolds number fluids would have a great technological impact in many fields. Few known mechanisms are able to propel such devices. Here we describe helical nanobelt (HNB) swimmers actuated by an electric field-generated electro-osmotic force. These HNB swimmers are designed with a head and a tail, similar to natural micro-organisms such as bacteria and their flagella. We show that these electro-osmotic propulsion of HNB swimmers achieve speeds (24 body lengths per second), force (1.3 nN), and pressure (375.5 Pa) above those demonstrated by other artificial swimmers based on physical energy conversion. Although nature’s bacteria are still more dynamic, this paper reports that the demonstrated electro-osmotic HNB microswimmers made a big step toward getting closer to their performances. Moreover, an unusual swimming behavior with discontinuous pumping propulsion, similar to jellyfish, was revealed at or above the speculated marginal limit of linear propulsion. These electro-osmosis propelled HNB swimmers might be used as biomedical carriers, wireless manipulators, and as local probes for rheological measurements.

Ultra-low noise high electron mobility transistors for high-impedance and low-frequency deep cryogenic readout electronics

Abstract: We report on the results obtained from specially designed high electron mobility transistors at 4.2 K: the gate leakage current can be limited lower than 1 aA, and the equivalent input noise-voltage and noise-current at 1 Hz can reach 6.3 nV/Hz1∕2 and 20 aA/Hz1∕2, respectively. These results open the way to realize high performance low-frequency readout electronics under very low-temperature conditions.

The control of human mesenchymal cell differentiation using nanoscale symmetry and disorder

Abstract: A key tenet of bone tissue engineering is the development of scaffold materials that can stimulate stem cell differentiation in the absence of chemical treatment to become osteoblasts without compromising material properties. At present, conventional implant materials fail owing to encapsulation by soft tissue, rather than direct bone bonding. Here, we demonstrate the use of nanoscale disorder to stimulate human mesenchymal stem cells (MSCs) to produce bone mineral in vitro, in the absence of osteogenic supplements. This approach has similar efficiency to that of cells cultured with osteogenic media. In addition, the current studies show that topographically treated MSCs have a distinct differentiation profile compared with those treated with osteogenic media, which has implications for cell therapies.

One-dimensional ZnO nanostructures: Solution growth and functional properties

Abstract: One-dimensional (1D) ZnO nanostructures have been studied intensively and extensively over the last decade not only for their remarkable chemical and physical properties, but also for their current and future diverse technological applications. This article gives a comprehensive overview of the progress that has been made within the context of 1D ZnO nanostructures synthesized via wet chemical methods. We will cover the synthetic methodologies and corresponding growth mechanisms, different structures, doping and alloying, position-controlled growth on substrates, and finally, their functional properties as catalysts, hydrophobic surfaces, sensors, and in nanoelectronic, optical, optoelectronic, and energy harvesting devices.

A 160-kilobit molecular electronic memory patterned at 10 11 bits per square centimetre

Abstract: The primary metric for gauging progress in the various semiconductor integrated circuit technologies is the spacing, or pitch, between the most closely spaced wires within a dynamic random access memory (DRAM) circuit. Modern DRAM circuits have 140 nm pitch wires and a memory cell size of 0.0408 mum(2). Improving integrated circuit technology will require that these dimensions decrease over time. However, at present a large fraction of the patterning and materials requirements that we expect to need for the construction of new integrated circuit technologies in 2013 have 'no known solution'. Promising ingredients for advances in integrated circuit technology are nanowires, molecular electronics and defect-tolerant architectures, as demonstrated by reports of single devices and small circuits. Methods of extending these approaches to large-scale, high-density circuitry are largely undeveloped. Here we describe a 160,000-bit molecular electronic memory circuit, fabricated at a density of 10(11) bits cm(-2) (pitch 33 nm; memory cell size 0.0011 microm2), that is, roughly analogous to the dimensions of a DRAM circuit projected to be available by 2020. A monolayer of bistable, [2]rotaxane molecules served as the data storage elements. Although the circuit has large numbers of defects, those defects could be readily identified through electronic testing and isolated using software coding. The working bits were then configured to form a fully functional random access memory circuit for storing and retrieving information.

Ultrahigh-Density Nanowire Lattices and Circuits

Abstract: We describe a general method for producing ultrahigh-density arrays of aligned metal and semiconductor nanowires and nanowire circuits. The technique is based on translating thin film growth thickness control into planar wire arrays. Nanowires were fabricated with diameters and pitches (center-to-center distances) as small as 8 nanometers and 16 nanometers, respectively. The nanowires have high aspect ratios (up to 106), and the process can be carried out multiple times to produce simple circuits of crossed nanowires with a nanowire junction density in excess of 1011 per square centimeter. The nanowires can also be used in nanomechanical devices; a high-frequency nanomechanical resonator is demonstrated.