Fig. 1. Structure diagram of the VOA array: (a) VOA- array structure; (b) Spiral orbit, where the small circles with solid points are collimators; (c) Liquid stop; (d) ITO annular electrodes.

Fig. 2. Working principle diagram of the VOA array with a spiral orbit: (a) Initial state (V = 0); (b) Attenuation state (V> 0)

Fig. 3. Working principle diagram of the VOA array with an annular orbit: (a) Annular orbit; (b) Initial state (V = 0); (c) Attenuation state (V > 0).

Fig. 4. Clear apertures for different voltages

Fig. 5. Attenuations for different voltages

Fig. 6. Fluid rate distribution for different time at 36 V：（a） 0.01 ms； （b） 0.1 ms； （c） 1 ms

Fig. 7. Clear aperture change with time, voltage:(a) 36 V; (b) 20 V