Zinc oxide (ZnO) nanowires (NWs) based ultraviolet (UV) sensors have been fabricated using different assembly techniques to form functional structures, aiming at the improvement of the performance of NW-based sensors for optoelectronic applications. NWs with diameters and lengths varying between 90-870 nm and 2-20 mu m, respectively, were synthesized by controlling the growth conditions in a chemical vapor transport system. Optical properties of NWs were studied by means of transmission spectroscopy. Electrical properties of single ZnO NW-based sensors were analyzed in dark and under UV illumination (at photon wavelength of lambda < 370 nm) as a function of the NW diameter. Results of the study indicate that reduction of the NW diameter below 200 nm leads to an improvement of the photocurrent (at lambda < 370 nm) up to 10(2) mu A and a decrease of the decay time around 150 s. These enhancements may help to improve the performance of ZnO-based optoelectronic devices. (C) 2013 Elsevier B.V. All rights reserved.