Miniaturized corona flow sensor operating in drift mobility increment mode for low flow velocity measurement

• Use of negative corona discharge for low flow velocity measurement.
• Employed drift mobility increment (DMI) mode instead of space charge displacement mode.
• Three sensor configurations investigated.
• Discussed significance as well as limitations of the presented approach.

We demonstrated low flow velocity measurement with a miniaturized corona flow sensor operating in drift mobility increment (DMI) mode. The corona flow sensor consisted of a corona flow probe residing in a small diameter flow tube. The corona flow probe had an electrode gap of ∼700 μm and was constructed with 50 μm stainless wire for cathode and nickel plated steel for anode. As evident in both the analytical and experimental corona current versus applied voltage curves, the corona current varied with the ozone concentration in the drift region. This also allowed the corona current to be responsive to air flow. The experimental corona current versus flow velocity trend was shown to be in agreement with the analytical trend. At an applied voltage of 1800 V, the corona flow sensor was able to measure flow velocities from 4.7 to 94.3 mm/s with a resolution of ∼5 mm/s. Three configurations consisting of the corona flow probe in different orientation with respect to the flow direction were investigated. We also showed that the sensitivity and operating range could potentially be tuned by adjusting the applied voltage. Finally, the significance and limitations of the results were also discussed.