In this paper, a development of high sensitivity for vital sign detector based on the fiber optic-based Fabry-Perot interferometer (FFPI) has been proposed. Two interested parameters; heart rate (HR), and also blood pressure (BP) are measured as the vital sign parameters for investigating the performance of the FFPI. Particularly, the proposed sensor is exploited to detect human arterial pulse for indicating the number of interference signals (fringes). A fringe counting technique is, consequently, applied in associate with the deflection of material technique to demodulate the observed number of fringes into HR and BP. Additionally, the reflective thin film with reflectance of approximately 55% is utilized for attaching to the human wrist during the measurement. Furthermore, a digital sphygmomanometer model OMRON HEM-7130 is employed as a reference sensor. After 20 times of repeatability on the same human subject, the FFPI could indicate the systolic and diastolic BP, as well as HR, with average error of 0.94%, 1.64%, and 1.01%, respectively. Moreover, the FFPI could determine the mentioned parameters in decimal numbers, as opposed to the reference sensor. This could, thus, verified that the FFPI is a very sensitive and more precise instrument for applying to the vital sign measurement.
Optical Harmonic Vernier Effect: A New Tool for High Performance Interferometric Fiber Sensors
