Recent Improvement of Medical Optical Fibre Pressure and Temperature Sensors

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. The presented sensors were examined carefully and demonstrated a pressure sensitivity in the range of [Formula: see text] = 2–10 [Formula: see text] and a resolution of better than [Formula: see text] = 10 Pa (0.1 cm H [Formula: see text] O). A static pressure test in 38 cmH [Formula: see text] O shows no drift of the sensor in a six-day period. Additionally, a dynamic pressure analysis demonstrated that the OFPTS never exceeded a drift of more than 130 Pa (1.3 cm H [Formula: see text] O) in a 12-h measurement, carried out in a cardiovascular simulator. The temperature sensitivity is given by [Formula: see text] [Formula: see text] , which results in a temperature resolution of better than [Formula: see text] = 0.1 K. Since the temperature sensing element is placed close to the pressure sensing element, the pressure sensor is insensitive to temperature changes.