This investigation describes a detailed analysis of the fabrication and testing of
optical fibre pressure and temperature sensors (OFPTS). The optical sensor of this research
is based on an extrinsic Fabry–Perot interferometer (EFPI) with integrated fibre Bragg
grating (FBG) for simultaneous pressure and temperature measurements. The sensor is
fabricated exclusively in glass and with a small diameter of 0.2 mm, making it suitable
for volume-restricted bio-medical applications. Diaphragm shrinking techniques based on
polishing, hydrofluoric (HF) acid and femtosecond (FS) laser micro-machining are described
and analysed.