Fabrication of freestanding Pt nanowires for use as thermal anemometry probes in turbulence measurements

We report a robust fabrication method for patterning freestanding Pt nanowires for use as thermal anemometry probes for small-scale turbulence measurements. Using e-beam lithography, high aspect ratio Pt nanowires (~300 nm width, ~70 µm length, ~100 nm thickness) were patterned on the surface of oxidized silicon (Si) wafers. Combining wet etching processes with dry etching processes, these Pt nanowires were successfully released, rendering them freestanding between two silicon dioxide (SiO2) beams supported on Si cantilevers. Moreover, the unique design of the bridge holding the device allowed gentle release of the device without damaging the Pt nanowires. The total fabrication time was minimized by restricting the use of e-beam lithography to the patterning of the Pt nanowires, while standard photolithography was employed for other parts of the devices. We demonstrate that the fabricated sensors are suitable for turbulence measurements when operated in constant-current mode. A robust calibration between the output voltage and the fluid velocity was established over the velocity range from 0.5 to 5 m s−1 in a SF6 atmosphere at a pressure of 2 bar and a temperature of 21 °C. The sensing signal from the nanowires showed negligible drift over a period of several hours. Moreover, we confirmed that the nanowires can withstand high dynamic pressures by testing them in air at room temperature for velocities up to 55 m s−1.

Use of Constant Current Mode to Allow Both Monopolar and Bipolar Interleaving at a Single Contact

A 56-year-old woman with advanced Parkinson disease underwent implantation of bilateral subthalamic nucleus (STN) deep brain stimulation with bilateral single-channel internal pulse generators (IPGs; Activa SC). Initial monopolar review suggested that ventral placement of the right STN lead and sufficient motor control could not be achieved without stimulation-induced side effects. She eventually underwent revision of the right STN lead. Subsequently, achieving the best balance between tremor control and dysarthria required interleaving of contacts 1 and 2 on the right. When she was due for battery replacement, she opted for a single, dual-channel, rechargeable IPG (Activa RC). Because her right STN lead used interleaving, at 125 Hz per program, and her left STN was programmed at 185 Hz without interleaving, the new dual-channel IPG required reprogramming of her left STN to be used for interleaving. However, the addition of any contact other than the most effective contact reduced her benefit, and thus it was decided to interleave two programs stimulating this contact in monopolar and bipolar mode. To achieve this, a change to constant current mode was required. Tremor control was re-established with this setting.

Lithium-Ion Laptop Battery Testing and Energy Recycling

Before recycling used lithium-ion laptop batteries, testing and sorting work is needed through charge and discharge tests. For current lithium-ion battery charge and discharge tests, the battery is discharged through a resistor. Thus, the energy in the process is all dissipated. In this paper, an energy-recycling battery test system model is introduced. In the system, a Li-ion 18650 battery can be charged at a constant current mode and a constant voltage mode and discharged at a constant current mode, which are realized by PWM-controlled DC-DC converters. The modes are automatically switched through a controller. In the discharging process, energy is transferred from the under-test battery to a storage battery, which can also serve as a charging source instead of the DC power supply to recycle the energy. The system is simulated using Matlab Simulink. Its test accuracy and energy-transferring efficiency is considerable. According to the simulation results, the system can save about 50% energy overall in one charge and discharge cycle.