Did alot of searching on this subject as well, what I found in the forum:
Do not place anything directly on the heating element, you can damage it.
perforated foil packets and perforated steel cans have been suggested,...
I tried both in my Elect ECB neither worked out for me. Chips were not getting enough oxygen to smolder in my experiment.
So far soaked chips do produce That thin blue smoke, but fizzle out pretty quickly.
now Its also argued that smoke penetration is only absorbed within the first hour anyway, so a long smoke is not really needed.
( IMO - That is debatable )
Currently I am looking to MOD mine out with an additional grate placed over the element similar to how the original grates are inserted, to which I can add Todd's Amazin Pellet smoker for a long smoke at higher temps. or you can try an additional grate with some type of pie pan ( not aluminum or galvanized steel ) filled with chips or chunks. Just a suggestion as I haven't tried either method out yet.
Hope this helps
Bren