Picometer-Scale Optical Electrohydrodynamic Sensing Method Based on F–P Interferometry

Accurate measurement of propulsion generated by electrohydrodynamics (EHD) contributes to the assessment of the thrust efficiency of drones and electric aircraft and may provide benefits in sustainability and stability. Here, we propose an electrohydrodynamic (EHD) measurement system based on an optical Fabry–Perot (F–P) sensor which senses the EHD thrust generated by a bipolar corona discharge via an elastic sensitive element. Static calibration experiments of the sensor were performed under such a pin-plate corona discharge system. The dynamic output characteristics of the sensors were tested under corona discharges with different polarities and discharge distances. The results show that the sensor has a linear operating region of 4–7 kV, a linearity of 99.6%, and a sensitivity of 257.7 pm/kV. Negative corona discharge leads to a higher spectral offset of the sensor compared with positive corona discharge. Continuous and simultaneous ionic wind sensing via an optical EHD sensor should provide accurate information about the performance of the propulsion system and contribute to the enhancement of the dynamic stability of the EHD actuator system.