We present a novel microplasma flow reactor using a dielectric barrier discharge (DBD) driven by repetitively nanosecond high-voltage pulses. Our DBD-based geometry can generate a non-thermal plasma discharge at atmospheric pressure and below in a regular pattern of micro-channels. This reactor can work continuously up to about 100 minutes in air, depending on pulse repetition rate and operating pressure. We here present the geometry and the main characteristics of the reactor. Pulse energies of 1.9 $\mu$J and 2.7 $\mu$J per channel at atmospheric pressure and 50 mbar, respectively, have been determined by time-resolved measurements of current and voltage. Time-resolved optical emission spectroscopy measurements have been performed to calculate the relative species concentrations and temperatures (vibrational and rotational) of the discharge. Effects of the operating pressure and the flow velocity on the discharge intensity have been investigated. In addition, the effective reduced electric field strength E/N has been obtained from the intensity ratio of vibronic emission bands of molecular nitrogen at different operating pressures. The derived effective E/N increases gradually from 500 Td to 600 Td when decreasing the pressure from one bar to 0.4 bar. Below 0.4 bar, further pressure reduction results in a significant increase in the effective E/N up to about 2000 Td at 50 mbar.
