Quality Assessment of Fiber Optic Pressure Sensors

BACKGROUND: Since the functional features of an artery can correlate to the risk of cardiovascular events, intra-arterial pressures can be utilized as a tool to gain more information about the condition of a vessel or even downstream structural features in the vasculature. Pressure waveforms contain information regarding peak systolic and diastolic pressures, as well as the elasticity and possibly sites of reflection. Similarly, the pulse wave velocity can be indicative of the mechanical properties of the arterial system. Intravascular fiber optic pressure sensors are one tool that can be used to record continuous pressure readings. OBJECTIVE: In order to effectively maximize the capabilities of the RJC fiber optic pressure sensors, they must be tested to fully understand the magnitude of their capabilities. Specific tests were performed to analyze the behavior, precision, and accuracy in different scenarios. METHOD: In vitro, four RJC fiber optic pressure sensors were immersed into known depths of water systematically. The pressures ranged from 0 mm H2O to 500 mmH2O. The pressure measurements included 6 measurements at low pressures (under 100 mmH2O) and 1 measurement at 500 mmH2O. Each pressure reading was approximately 10 seconds and the sensor recorded pressure measurements at a frequency of 1000 Hz. At each pressure reading, the variation and behavior of each individual sensor, the discrepancies between two sensors, as well as the accuracy compared to the theoretical pressure value were evaluated. In addition, the pressure receiver box and various methods of calibration were tested to ensure that there were not other factors causing a bias on the sensors' measurements. RESULTS: The sensors were found to have the capability of giving instantaneous pressure values with a precision of 0.03 mm Hg. The standard deviation of one pressure sensor at a constant pressure for 10 seconds was 0.15mmHg. The average difference between two sensors' pressure values that were calibrated simultaneously was 0.66 mmHg. Lastly, the accuracy of the sensors decreased at higher pressures. Specifically, at a pressure of 37 mmHg, the accuracy of the sensors was approximately 1.9%. CONCLUSION: This data will be important for all future experiments and measurements that involve the RJC fiber optic pressure sensors. With a complete understanding of quantitatively how the sensors behave, it will be feasible to analyze results of future pressure measurements.