Miniature Fabry-Perot pressure sensor created by using UV-molding process with an optical fiber based mold

Abstract

We present a miniature Fabry-Perot pressure sensor fabricated at the tip of an optical fiber with a pre-written Bragg grating by using UV-molding polymer process. The mold is constructed by integrating an optical fiber of 80 μm diameter with a zirconia ferrule. The optical fiber based mold makes it possible to use optical aligning method to monitor the coupled intensity between the mold-side and replica-side fibers, rendering a maskless alignment process with a submicrometer accuracy. A polymer-metal composite thin diaphragm is employed as the pressure transducer. The overall sensor size is around 200 μm in diameter. Experimental study shows that the sensor exhibits a good linearity over a pressure range of 1.9-7.9 psi, with a sensitivity of 0.0106 μm/psi. The fiber Bragg grating is exploited for simultaneous temperature measurements or compensation for temperature effects in pressure readings. The sensor is expected to benefit many fronts that require miniature and inexpensive sensors for reliable pressure measurement, especially biomedical applications.

Fiber-optic combined FPI/FBG sensors for monitoring of radiofrequency thermal ablation of liver tumors: ex vivo experiments

“…Several EFPI-based configurations have been recently presented [21][22][23][24][25][26][27][28]; in addition, EFPI-based medical devices are commercially available [29]. It is possible to combine an EFPI probe with a fiber Bragg grating (FBG) [30,31], acting as temperature sensor in proximity of the EFPI sensor, to provide a dual sensing with cross compensation; such configuration has been proposed in [26][27][28]. In [26,27], a dual EFPI/FBG sensor is proposed, achieving 1.68 nm∕kPa pressure sensitivity, and 1.7 nm∕°C cross sensitivity; [28] proposes a novel manufacturing technique based on UV mold, with limited biocompatibility, and 1.53 nm∕kPa and 15.8 nm∕°C sensitivity coefficients.…”

“…It is possible to combine an EFPI probe with a fiber Bragg grating (FBG) [30,31], acting as temperature sensor in proximity of the EFPI sensor, to provide a dual sensing with cross compensation; such configuration has been proposed in [26][27][28]. In [26,27], a dual EFPI/FBG sensor is proposed, achieving 1.68 nm∕kPa pressure sensitivity, and 1.7 nm∕°C cross sensitivity; [28] proposes a novel manufacturing technique based on UV mold, with limited biocompatibility, and 1.53 nm∕kPa and 15.8 nm∕°C sensitivity coefficients. Commercial devices [29], on the other side, do not offer dual sensing option, and are not compatible with >60°C temperature operation.…”

“…The current state of the art of dual EFPI/FBG [26][27][28] does not allow an adequate cross compensation, as the temperature-sensing FBG is located few millimeters far from the EFPI tip, hence is exposed to a much different temperature making the compensation ineffective. In this paper, we present a combined EFPI/FBG probe in which the EFPI sensor exhibits a small temperature coefficient (51.9 pm∕°C, 32 times smaller than [26] and 304 times smaller than [28]); this allows a neat separation between temperature and pressure sensing, which is essential in presence of such a steep gradient. The dual probe exhibits accuracy of 40 Pa and 0.2°C and is based on an all-glass design, which complies with basic biocompatibility requirements.…”

A microscale optical implant for continuous in vivo monitoring of intraocular pressure

“…Such large implants have damaged surrounding 1 tissues and led to medical complications 66,67 . Previously investigated optical sensing approaches include a fiber-tip-based interferometry for hydrostatic pressure sensing [68][69][70][71][72][73][74] , a visualidentification-based method applied to pressure-sensitive microfluidic or micromechanical structures 75,76 , and laser-excited fluorescence measurements for ICP and IOP monitoring 77,78 . These approaches are promising, and with more improvements in terms of miniaturization and readout techniques, they may become practical approaches for IOP monitoring.…”

Compressible fiber optic micro-Fabry-Pérot cavity with ultra-high pressure sensitivity

“…A pressure sensor based on micro FP cavity commonly uses an elastic diaphragm at the fiber tip such as SiO 2 /silica, polymer, silver and graphene film [12][13][14][15][16][17][18][19][20]. The pressure sensitivity of the diaphragm-based fiber tip FP sensor is defined as the ratio of the FP cavity length variation to the pressure change, which critically depends on the size and the mechanical quality of the diaphragm employed.…”