Oliso already had a sous vide machine that used induction, but we wanted to try and come up with an enclosed Sous Vide system that could be set on top of an induction top. The goal was to see if you could use induction to get a consistent temperature in the clamshell water bladder. Since the cooktop also heats metal that's about 1 cm from the coil, only the bottom layer would be directly heated from the metal mesh that was inside. The hope was that the bottom bladder would conduct heat to the top bladder, and that if it was well insulated it might reach an equilibrium. Another issue was where to mount the PID controller. If you mounted it to the bottom, the top was too cool. Mounted at the top and the bottom overheated. At the crease didn't work, either. Other metal substrates were tried as well (thick cast iron plates, thin baking sheets, etc), but the real issue was the temperature difference between the top and bottom bladder. Even though they were technically connected (clamshell style), the water couldn't really circulate through, and the heat didn't conduct well enough between the two. 

Steel mesh inside bag to create heat via induction. 

Temp controller in fold crease to try and get a more consistent temperature (also doesn't work). 

Clamshell water filled bladder with silicone sheet inside. 

Top sleeve to hold temperature controller. Water on bottom gets too hot. 

Created new water filled vessel using two pans and a silicone sheet.

Temperature control from induction cooker vessel added to bladder.

Bottom sleeve to hold temperature controller. Top layer doesn't get hot enough. 

Bottom of new vessel to test induction strategy. Trapped air becomes an issue (balloon effect).