e  •  00  •  ~  ~  ~  ~  =  ~  ~  ~  N  ’"\,Ci  N  0  ....  QO  rJJ  =› (’D  (’D  .....  Ul  0  ....  N  0  d  r.,;_  _."-0  "-0  00  "’""’  ’N  ~  =  "’""’  FIG. 4B  Dispersed charged  particles  {ii}  Trigger applied for pH--contro!  substance (graduafly reduces  surfc1Ce  charge)  (iii)  Assembled,  ordered 3D array 