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All-fiber high-sensitivity pressure sensor with SiO2 diaphragm

The design and fabrication of a miniature fiber Fabry-Perot pressure sensor with a diameter of 125 m are presented. The essential element in the process is a thin SiO2 diaphragm that is fusion spliced at the hollow end of an optical fiber. Good repeatability and high sensitivity of the sensor are achieved by on-line tuning of the diaphragm thickness during the sensor fabrication process. Various sensor prototypes were fabricated, demonstrating pressure ranges of from 0 to 40 kPa to 0 to 1 MPa. The maximum achieved sensitivity was 1.1 rad/40 kPa at 1550 nm, and a pressure resolution of 300 Pa was demonstrated in practice. The presented design and fabrication technique offers a means of simple and low-cost disposable pressure sensor production.

Miniature fiber-optic pressure sensor with a polymer diaphragm

The fabrication and experimental investigation of a miniature optical fiber pressure sensor for biomedical and industrial applications are described. The sensor measures only 125 m 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 FabryPerot interferometer is formed between the inner fibercavity interface and the diaphragm. The fabrication technique is described in detail. Different sensor prototypes were fabricated upon 125 m-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. 2005 Optical Society of America

Miniature all-glass robust pressure sensor

This paper describes a newly designed all-glass miniature ( 125 ?m) fiber-optic pressure sensor design that is appropriate for high-volume manufacturing. The fabrication process is based on the chemical etching of specially-designed silica optical fiber, and involves a low number of critical production operations. The presented sensor design can be used with either single-mode or multi-mode lead-in fiber and is compatible with various types of available signal processing techniques. A practical sensor sensitivity exceeding 1000 nm/bar was achieved experimentally, which makes this sensor suitable for low-pressure measurements. The sensor showed high mechanical stability, good quality of optical surfaces, and very high tolerance to pressure overload.

Miniature all-fiber FabryPerot sensor for simultaneous measurement of pressure and temperature

This article presents a miniature, high-sensitivity, all-silica FabryPerot fiber-optic sensor suitable for simultaneous measurements of pressure and temperature. The proposed sensor diameter does not exceed 125 ?m and consists of two low-finesse FabryPerot resonators created at the tip of an optical fiber. The first resonator is embodied in the form of a short air cavity positioned at the tip of the fiber. This resonator utilizes a thin silica diaphragm to achieve the sensors pressure response. The second resonator exploits the refractive index dependence of silica fiber in order to provide the proposed sensors temperature measurement function. Both resonators have substantially different lengths that permit straightforward spectrally resolved signal processing and unambiguous determination of the applied pressure and temperature.

Photoplethysmographic heart rate and blood pressure estimation in dynamic condition

This paper describes a novel, unobtrusive photoplethysmographic device and experiments conducted in a dynamic condition. The device complements a photoplethysmograph with a dynamometer, an accelerometer, and a thermometer. We built it in the door handle of a refrigerator and made tests during the door opening and closing. Short-term PPG signals were obtained across all fingers pulling the handle. In parallel, we measured the standard ECG lead II as a reference for the detected heartbeat verification. The blood pressure of each participant was registered before each experimental trial by a standard sphygmomanometer. Based on the PPG signals, we ran our computer algorithms for detecting the heartbeats and estimating the mean blood pressure. Satisfactory results were achieved for heartbeats, with 97.62% sensitivity and 90.31% precision. However, blood pressure estimation appeared to be not very efficient - neither linear nor exponential modeling could lower the estimated mean absolute error in comparison to referential mean blood pressures below 6 mmHg.