Hi, I’m considering getting the CuboAi sleep sensor pad, which is placed under the baby’s mattress. As the pad is not completely flat, is it recommended to place under a mattress, or will it create too much of a lump and cause the baby to roll? Is it okay to put something like this in a bassinet as well as a cot? Thanks

How old is your baby?
What are your concerns which leads you to wanting to use a monitor?

Please check with instructions before using any product with your baby.
Does the Company recommend the use of this product in a bassinet?

If you see that this product (or any other product) creates a sleep surface that it not flat, its use would not be recommended.
Red Nose recommends that an infant’s sleep surface is firm, clean, well-fitting & flat (not elevated)

Red Nose does not recommend the routine use of monitors to reduce the risk of SUDI (Sudden Unexpected Death in Infancy)
However, for some parents, using a monitor can be helpful. Many parents describe increased anxiety by “false alarms”
https://rednose.org.au/article/do-baby-monitors-reduce-the-risk-of-sudden-unexpected-death-in-infancy