Liquid-air based Fabry-Pérot cavity on fiber tip sensor

• Published in: Optics express Vol. 24; no. 8; pp. 8054 - 8065
• Main Authors: Llera, Miguel, Aellen, Thierry, Hervas, Javier, Salvadé, Yves, Senn, Pascal, Le Floch, Sébastien, Keppner, Herbert
• Format: Journal Article
• Language: English
• Published: United States 18.04.2016
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/OE.24.008054

This paper presents a Fabry-Perot fiber tip sensor based on an air-liquid filled cavity. The cavity is sealed off by a thin gold coated membrane of parylene C, between 300 and 350 nm, creating a particularly flexible diaphragm. In order to retrieve and track the cavity of interest from other cavities formed within the sensor tip, a signal processing of the feedback signal is performed by inverse fast Fourier transform. The experimental sensor has been manufactured and tested for temperature, giving cavity length sensitivities of 6.1 nm/°C and 9.6 nm/°C for temperature increase and decrease respectively. The external gas pressure response gives a sensitivity of 15 nm/kPa. The fiber sensor has also been adapted for force sensing after silicone embedment and has shown a sensitivity of about 8.7 nm/mN. Finally, the sensor has been tested on insertion into a human temporal bone, proving that it could be an interesting candidate for insertion force monitoring for robotic cochlear implantation.