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Nat Commun ; 10(1): 3299, 2019 07 24.
Artigo em Inglês | MEDLINE | ID: mdl-31341167


The striking similarity between biological locomotion gaits and the evolution of phase patterns in coupled oscillatory network can be traced to the role of central pattern generator located in the spinal cord. Bio-inspired robotics aim at harnessing this control approach for generation of rhythmic patterns for synchronized limb movement. Here, we utilize the phenomenon of synchronization and emergent spatiotemporal pattern from the interaction among coupled oscillators to generate a range of locomotion gait patterns. We experimentally demonstrate a central pattern generator network using capacitively coupled Vanadium Dioxide nano-oscillators. The coupled oscillators exhibit stable limit-cycle oscillations and tunable natural frequencies for real-time programmability of phase-pattern. The ultra-compact 1 Transistor-1 Resistor implementation of oscillator and bidirectional capacitive coupling allow small footprint area and low operating power. Compared to biomimetic CMOS based neuron and synapse models, our design simplifies on-chip implementation and real-time tunability by reducing the number of control parameters.

Geradores de Padrão Central/fisiologia , Marcha , Nanotecnologia , Robótica , Relógios Biológicos , Nanopartículas , Óxidos , Compostos de Vanádio
Nanoscale ; 11(13): 6016-6022, 2019 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-30869095


The 1T phase of tantalum disulfide (1T-TaS2) possesses a variety of charge-density-wave (CDW) orders, and as a result, it attracts an increasing amount of academic and technological interest. Researchers have devoted tremendous efforts towards understanding the impacts of doping, alloying, intercalation or other triggering agents on its charge density wave orders. In this work, we demonstrate that incorporating potassium chloride (KCl) during chemical vapor deposition (CVD) of TaS2 can control the phase (1T, 2H or metal nanowires) via the intercalation of potassium ions (K+) between TaS2 layers. Finally, we demonstrate that K+ not only impacts the structure during synthesis but also strongly impacts the CDW phase transition as a function of temperature, increasing the nearly commensurate (NCCDW) to commensurate (CCDW) transition to just below room temperature.

Beilstein J Nanotechnol ; 3: 712-21, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23213635


Monitoring emissions in high-temperature-combustion applications is very important for regulating the discharge of gases such as NO(2) and CO as well as unburnt fuel into the environment. This work reports the detection of H(2) and CO gases by employing a metal-metal oxide nanocomposite (gold-yttria stabilized zirconia (Au-YSZ)) film fabricated through layer-by-layer physical vapor deposition (PVD). The change in the peak position of the localized surface plasmon resonance (LSPR) was monitored as a function of time and gas concentration. The responses of the films were preferential towards H(2), as observed from the results of exposing the films to the gases at temperatures of 500 °C in a background of dry air. Characterization of the samples by XRD and SEM enabled the correlation of material properties with the differences in the CO- and H(2)-induced LSPR peak shifts, including the relative desensitization towards NO(2). Sensing characteristics of films with varying support thicknesses and metal-particle diameters have been studied, and the results are presented. A comparison has been made to films fabricated through co-sputtered PVD, and the calibration curves of the sensing response show a preferential response towards H(2). The distinction between H(2) and CO responses is also seen through the use of principal-component analysis (PCA). Such material arrangements, which can be tuned for their selectivity by changing certain parameters such as particle size, support thickness, etc., have direct applications within optical chemical sensors for turbine engines, solid-oxide fuel cells, and other high-temperature applications.