Heart signals sensor based on optical fiber Fabry-Perot interferometer

A simple and inexpensive method of measuring heart beats was established using Fabry-Perot interferometry (FPI). The sensor consists of a bracelet, the Fabry-Perot cavity is formed with a thin aluminum foil and the tip of a singlemode fiber optic. The fiber and aluminum foil are inserted into bracelet by means of easily assembled mechanical components. Fiber-coupled laser diode (1550 nm wavelength) was used to provide the optical signal through a 50:50 fiber coupler. Furthermore, we used a photodetector to transform this signal into an electrical one and an oscilloscope to analyze this signal. The sensor measures heart rate in the time domain, detecting interference fringes through the sensor and displayed on an oscilloscope. The interference phenomenon takes place in the Fabry-Perot cavity (CFP) which is formed by the thin aluminum plate and the tip of the optical fiber. By analyzing the signal from the oscilloscope, it is possible to measure the heart rate. The analysis presented in this work shows several advantages over traditional electrocardiograms, real-time measurement and simplification in the experimental setup, coupled with its high sensitivity for the analysis of cardiograms.