A spring base is not a problem but we have a tip to ensure your spring base is firm.
Before looking at your base, first ensure that the mattress you have is able to be used with the Babysense 7. The main thing to ensure is that the mattress does not have memory foam, and that there is a solid and firm connection between the mattress and sensor pads. This means ensuring your cot has the a firm base.
If your cot base has a spring structure, we normally request you place one or two plywood boards (depending on whether one or two sensors are being used) to assist with this:
If you have any question, let our Babysense Customer Support Team know.