The Optical Fibre Nanowire (OFN) is a potential building block in future micro- and nano-photonic device since it offers a number of unique optical and mechanical properties. In this thesis, the background and fundamental features of nanowires are introduced; the theory, design and demonstration of novel nanowire devices are discussed. At first, a short adiabatic taper tip is manufactured, and it is used as optical tweezers for trapping 1μm microspheres. Then, the most important devices - the OFN resonators including the simple Optical Nanowire Loop Resonator (ONLR) and complicated 3D Optical Nanowire Microcoil Resonator (OMNR) - are investigated theoretically and experimentally. A one-turn loop resonator and two-, three-, and four-turn ONMR are demonstrated experimentally; several kinds of methods on optimizing the ONMR profile are presented to make the manufacture of high-Q ONMRs easier. In order to protect and stabilize the ONMR, embedding the device in Teflon is demonstrated. Finally, more applications in refractometric sensing are presented: schemes of sensors based on an embedded ONLR and ONMR are presented. The sensor sensitivities are calculated: 700 nm/RIU (RIU is the Refractive Index Unit) can be achieved at the wavelength of 970 nm for a diameter of 600 nm. Additionally, a refractometric sensor based on an embedded ONMR is demonstrated experimentally; its sensitivity is about 40 nm/RIU.