Research On Fractional Flow Reserve Measurement System Based On Micro-Opto-Electro-Mechanical Systems (MOEMS) Pressure Sensing Technology

The cardiovascular disease accounts for a large proportion of deaths,which is the first cause of death for residents in China.For a long time,coronary angiography and intravascular ultrasound have been the reference standards for the interventional diagnosis of vascular stenosis.However,their access to vascular stenosis function information is very limited.The fractional flow reserve(FFR)based on pressure measurement is an invaluable functional evaluation tool.FFR is an accurate lesionspecific indicator of whether specific narrowed or coronary arteries can cause ischemia.Most of the current FFR measurement systems use traditional piezoelectric sensors,which have limitations such as large drift and susceptibility to electromagnetic interference.Miniature optical pressure sensors have characteristics such as small size,high sensitivity,small drift,and immunity to electromagnetic interference.It is more and more widely used in FFR measurement.This thesis mainly aims at FFR parameter measurement and selects MOEMS(Micro-Opto-Electro-Mechanical Systems)pressure sensing technology for research,designs and builds the pressure calibration device of the sensor measurement system.By establishing the pressure sensing benchmark test system and micro-pressure measurement environment,the pressure of the sensor measurement system is calibrated.To obtain the relationship between the sensor cavity length change and the pressure value,the white light low coherence interference method is used to demodulate the reflection spectrum under different loading pressures.By comparing and analyzing the measured pressures of the sensor measurement system,the MOEMS pressure sensor measurement system is verified to have high accuracy and good correlation.In order to develop optical pressure sensors with higher performance,this paper also proposes a new plasmonic surface lattice resonances(SLRs)structure composed of metaldielectric-metal nanopillar arrays,which is asymmetric and has excellent performance in the dielectric environment.Due to the optimized geometric parameters,the structure has a quality factor of 86.Moreover,when the spatial distance between designed nanopillar array and the metal plate in the structure changes within the range of 5-9nm,the resonance wavelength’s shift is very obvious.For every 1nm interval change of the spatial distance,the resonance wavelength shifts by 42 nm,indicating that the structure response is very sensitive and relevant advantage,which is very suitable for high sensitivity pressure sensing system.Furthermore,it is found that the tunability can be obtained by changing the geometric parameters of the structure and the spatial distance from the metal.The research lays the foundation for further exploration to build an optical pressure sensing system that accurately measures FFR,and provides a technical basis for the realization of diagnostic equipment manufacturing wish small-size,high-sensitivity,high-precision pressure sensors and high-demand interventional.