Sensing absolute air pressure using micro corona discharge

We demonstrated the sensing of absolute air pressure using micro corona discharge. Pin-to-plane electrode configuration with an electrode gap of ∼1.2 mm was used. The length and height of the plane were 3 mm and 1 mm, respectively. The electrodes were fabricated using a copper electroplating process and subsequently enclosed in a channel. The inception voltage was ∼1400 V. Analytical plot of corona current versus absolute air pressure showed that corona current decreased with the increase of absolute air pressure. In the experiment, applied voltages from 2500 to 3500 V and absolute air pressure from 101.3 to 173.7 kPa were used. The experimental corona current ranged from ∼2 to ∼10 μA. It was observed to decrease with increased absolute air pressure and therefore in agreement with the analytical trend. At a given applied voltage, the upper limit of the pressure measurement range was determined by the extinguishment of the corona discharge. On the other hand, the lower limit was determined by the transition of the corona discharge into streamers. The pressure measurement range could be extended by adjusting the applied voltage accordingly. Limitations of this approach include dependence on gas composition and generation of ionized species.