In this paper we review the fabrication and characterisation techniques of microstructured optical fibre (MOF) tapers, their fundamental waveguiding properties and potential applications. We fabricate photonic crystal fibre tapers without collapsing the air-holes, and confirm this along the taper with a non-invasive probing technique. We then describe the fundamental property of such tapers associated with the leakage of the core mode that leads to long wavelength loss. We also revisit the waveguiding properties in another form of tapered MOF photonic wires, which transition through waveguiding regimes associated with how strongly the mode is isolated from the external environment. We explore these regimes as a potential basis for evanescent field sensing applications, in which we can take advantage of controlled air-hole collapse as an extra dimension to these photonic wires.