Monitoring the traffic and the structural health of traffic tunnels requires numerous sensors. Powering these remote and partially embedded sensors from ambient energies will reduce maintenance costs, and improve the sensor network performance. This work reports on vibration levels detected in railway and road tunnels as a potential energy source for embedded sensors. The measurement results showed that the vibrations at any location in the road tunnel and at the wall in the railway tunnel are too small for useful vibration harvesting. In contrast, the railway sleeper features usable vibrations and sufficient mounting space. For this application site, a robust piezoelectric vibration harvester was designed and equipped with a power interface circuit. Within the field test, it is demonstrated that sufficient energy is harvested to supply a microcontroller with a radio frequency (RF) interface.

Short AbstractThe reduction of the thermal conductivity induced by nano-patterning is one of the major approaches for tailoring thermoelectric material properties. Here, we chose two individual bismuth telluride nanowires (NWs), one with a strong diameter variation (NW1) and the other with smooth sidewalls (NW2). We investigated the role of the diameter variation by means of a combined fullthermoelectrical, structural and chemical characterisation on single nanowires. The electrical conductivity of both NWs exceeds the bulk value indicating the presence of a topological surface state. The thermal conductivity of NW2 compares to the bulk, while NW1 is about half that of NW2.Above. HRTEM micrograph of the smooth NW side and the amorphous shell of varying thickness of about (5 ± 1) nm. The inset shows a power spectrum of the NW core.

We report on the realisation of a chip-based multipole ion trap manufactured using microelectromechanical systems (MEMS) technology. It provides ion confinement in an almost field-free volume between two planes of radiofrequency electrodes, deposited on glass substrates, which allows for optical access to the trap. An analytical model of the effective trapping potential is presented and compared with numerical calculations. Stable trapping of argon ions is achieved and a lifetime of 16 s is measured. Electrostatic charging of the chip surfaces is studied and found to agree with a numerical estimate.

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We present a novel planar multipole radiofrequency (rf) ion trap built with microfabrication technologies on a transparent substrate. Simulations were performed using an analytical model of the effective potential to determine the trapping capabilities of different designs. Based upon these simulations an ion trap was designed, fabricated and successfully characterized in first experiments at ultra high vacuum conditions.