Open String Noise During Sweep Picking

While performing a sweep, many times after moving my left hand fingers from one string to another, it will cause that string to vibrate and cause the open note to be heard. is it a matter of positioning my hand better for a more direct vertical attack to the frets, or perhaps with greater speed, my fingers will return to the string before much of its open note can be heard?
any suggestions or reference to a tutorial on how to prevent this?

thanks!