We report on a functional, highly reproducible and cost effective sensing platform based on photonic crystal fibers
(PCFs). The platform consists of a centimeter-length segment of an index-guiding PCF fusion spliced to standard single
mode fibers (SMFs). The voids of the PCF are intentionally sealed over an adequate length in the PCF-SMF interfaces.
A microscopic collapsed region in the PCF induces a mode field mismatch which combined with the axial symmetry of
the structure allow the efficient excitation and recombination or overlapping of azimuthal symmetric modes in the PCF.
The transmission or reflection spectrum of the devices exhibits a high-visibility interference pattern or a single, profound
and narrow notch. The interference pattern or the notch position shifts when the length of the PCF experiences
microelongations or when liquids or coatings are present on the PCF surface. Thus, the platform here proposed can be
useful for sensing diverse parameters such as strain, vibration, pressure, humidity, refractive index, gases, etc. Unlike
other PCF-based sensing platforms the multiplexing of the devices here proposed is simple for which it is possible to
implement PCF-based sensor arrays or networks.