Miniature fiber-optic pressure sensor with a polymer diaphragm
Applied Optics Vol. 44, Issue 14, pp. 2736-2744 (2005) •doi: 10.1364/AO.44.002736

The fabrication and experimental investigation of a miniature optical fiber pressure sensor for biomedical and industrial applications are described. The sensor measures only 125 µm in diameter. The essential element is a thin polymer diaphragm that is positioned inside the hollow end of an optical fiber. The cavity at the fiber end is made by a simple and effective micromachining process based on wet etching in diluted HF acid. Thus a Fabry–Perot interferometer is formed between the inner fiber–cavity interface and the diaphragm. The fabrication technique is described in detail. Different sensor prototypes were fabricated upon 125 µm-diameter optical fiber that demonstrated pressure ranges from 0 to 40 and from 0 to 1200 kPa. A resolution of less than 10 Pa was demonstrated in practice. The fabrication technique presented facilitates production of simple and low-cost disposable pressure sensors by use of materials with that ensure the required biocompatibility.