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The high-performance pH-sensing membrane of extended-gate field-effect transistors (EGFET) composed of high-conductivity horizontally aligned carbon nanotube thin films (HACNTFs) after oxygen plasma treatment is successfully demonstrated. The 10-µm-wide catalytic metal lines with 60 µm interspace produced CNT vertical plates, and the plates were mechanically pulled down and densified to form HACNTFs. A large amount of oxygen-containing functional groups are decorated on the CNTs after the oxygen plasma treatment. These functional groups act as the sensing sites and respond to the H + or OH % ions in solutions with different pH values. Therefore, these functionalized HACNTFs as pH-EGFET-sensing membranes can achieve a high voltage sensitivity of 40 mV/pH and high current sensitivity of 0.78 µA 1/2 /pH. Moreover, large linearity of 0.998 is measured in a wide sensing range from pH 1 to 13. These results reveal that the oxygen plasma treatment is an effective way to improve the CNTsensing characteristics in pH-EGFET sensors.

Transparent ultraviolet (UV) detectors with nanoheterojunctions (NHJs) of p-type NiO and n-type ZnO nanowires (ZnO-NWs) were successfully fabricated using a DC sputtering system and a hydrothermal process, respectively. After annealing in nitrogen ambient, the near-band-edge emission to deep level emission ratio (NBE/DLE) of ZnO-NWs gradually increased as the temperature increased and reached a maximum of 28.9 at a temperature setting of 500 °C. In contrast, after annealing in oxygen atmosphere, the NBE/DLE of ZnO-NWs initially increased from 1.2 to 5.9 and then decreased to 3.2. At a reverse bias of 2 V, the devices with the 500-°C-N2-annealed ZnO-NWs exhibited better sensitivity (JUV/JDark = 5.65; JVisible/JDark = 1.35) to UV light (365 nm, 0.3 mW/cm2) than those with the as-grown ZnO-NWs (JUV/JDark = 4.98; JVisible/JDark = 3.82) because the structural defects in ZnO-NWs were effectively eliminated after annealing in nitrogen ambient at 500 °C.

In this study, a simple densification method for carbon nanotube (CNT) pillars is proposed to achieve high-performance field emission characteristics and stable emission. Through capillary force during solution evaporation, the CNT density in each pillar can be increased by about six times without causing damage to the crystallinity of CNTs. The densified CNT pillars exhibit lower series resistance, sharper pillars, better contacts, higher thermal conductivity, and better mechanical stiffness than as-grown ones. Therefore, the threshold field of the field emitter with such CNT pillars of 50 µm height can be reduced to 1.98 V/µm, as compared with 2.2 V/µm for the undensified ones. Moreover, the fluctuation of field-emission current decreases from 15.5 to 9.4% after the stress tests at a field of 2 V/µm for 1800 s. These findings imply that the densified CNT pillars are promising for the field-emission applications.

Aerosol particles in urban areas are deposited in street canyons due to the wind field generated by building blocks. The purpose of this study was to discuss with CFD software the effect on lowering the aerosol concentration in urban space by means of active and auxiliary adjustable wind deflectors installed on the building facade to divert and control the micro-climate wind environment surrounding the buildings. The results suggested that, the wind deflector could produce an enormous improving efficiency for channelizing the particles.