Integrative Biomimetics of Autonomous Hexapedal Locomotion.

Despite substantial advances in many different fields of neurorobotics in general, and biomimetic robots in particular, a key challenge is the integration of concepts: to collate and combine research on disparate and conceptually disjunct research areas in the neurosciences and engineering sciences. We claim that the development of suitable robotic integration platforms is of particular relevance to make such integration of concepts work in practice. Here, we provide an example for a hexapod robotic integration platform for autonomous locomotion. In a sequence of six focus sections dealing with aspects of intelligent, embodied motor control in insects and multipedal robots-ranging from compliant actuation, distributed proprioception and control of multiple legs, the formation of internal representations to the use of an internal body model-we introduce the walking robot HECTOR as a research platform for integrative biomimetics of hexapedal locomotion. Owing to its 18 highly sensorized, compliant actuators, light-weight exoskeleton, distributed and expandable hardware architecture, and an appropriate dynamic simulation framework, HECTOR offers many opportunities to integrate research effort across biomimetics research on actuation, sensory-motor feedback, inter-leg coordination, and cognitive abilities such as motion planning and learning of its own body size.

A new approach to the spectral analysis of liquid membrane oscillators by Gábor transformation.

Liquid membrane oscillators very frequently have an irregular oscillatory behavior. Fourier transformation cannot be used for these nonstationary oscillations to establish their power spectra. This important point seems to be overlooked in the field of chemical oscillators. A new approach is presented here based on Gábor transformation allowing one to obtain power spectra of any kind of oscillations that can be met experimentally. The proposed Gábor analysis is applied to a liquid membrane oscillator containing a cationic surfactant. It was found that the power spectra are strongly influenced by the presence of various added substances.

On the possibility of molecular recognition of taste substances studied by Gábor analysis of oscillations.

A liquid membrane oscillator containing nitromethane as membrane material has been investigated. The influence of substances responsible for taste belonging to four classes (sweetness, saltiness, sourness and bitterness) on oscillation patterns of liquid membrane oscillators with cationic surfactant benzyldimethyltetradecylammonium chloride (BDMTAC) was examined. A new approach based on Gábor transformation is proposed for obtaining the power spectra of the observed oscillating signals and for establishing "fingerprints" of the investigated substances. It was shown that two-dimensional form of these power spectra might be used efficiently for this purpose.

Stable field emission from arrays of vertically aligned free-standing metallic nanowires.

We present a fully elaborated process to grow arrays of metallic nanowires with controlled geometry and density, based on electrochemical filling of nanopores in track-etched templates. Nanowire growth is performed at room temperature, atmospheric pressure and is compatible with low cost fabrication and large surfaces. This technique offers an excellent control of the orientation, shape and nanowires density. It is applied to fabricate field emission arrays with a good control of the emission site density. We have prepared Co, Ni, Cu and Rh nanowires with a height of 3 µm, a diameter of 80 nm and a density of ∼10(7) cm(-2). The electron field emission measurements and total energy distributions show that the as-grown nanowires exhibit a complex behaviour, first with emission activation under high field, followed by unstable emission. A model taking into account the effect of an oxide layer covering the nanowire surface is developed to explain this particular field emission behaviour. Finally, we present an in situ cleaning procedure by ion bombardment that collectively removes this oxide layer, leading to a stable and reproducible emission behaviour. After treatment, the emission current density is ∼1 mA cm(-2) for a 30 V µm(-1) applied electric field.

Template-grown NiFe/Cu/NiFe nanowires for spin transfer devices.

We have developed a new reliable method combining template synthesis and nanolithography-based contacting technique to elaborate current perpendicular-to-plane giant magnetoresistance spin valve nanowires, which are very promising for the exploration of electrical spin transfer phenomena. The method allows the electrical connection of one single nanowire in a large assembly of wires embedded in anodic porous alumina supported on Si substrate with diameters and periodicities to be controllable to a large extent. Both magnetic excitations and switching phenomena driven by a spin-polarized current were clearly demonstrated in our electrodeposited NiFe/Cu/ NiFe trilayer nanowires. This novel approach promises to be of strong interest for subsequent fabrication of phase-locked arrays of spin transfer nano-oscillators with increased output power for microwave applications.