I used a camera motion control unit by SYRP on a camera slider with an Elektroluch attached to it, to do automated slow moves across EMF emitters… skip to 1’58" in this vid, theres a shot tracking the Eletroluch across laptop keyboard using motion control (Elektroluch is on an arm, to avoid picking up the SYRP Genies motor EMF)
With eBow it would be a little more difficult as motion control is not silent (the motion controllers motor makes audible noise) so it would pollute acoustic recordings…
But doing it manually eg slowly sliding eBow along a string, you can hear it alter the tonality as it crosses nodes and antinodes etc… The only difference between Elektroluch and an eBow is there is some lag with an eBow - its takes a few seconds for the string to respond to an eBow, whereas EMF emitters are constant so doppler/movement is immediate