[LCoder]

I spent years in a previous job developing acute care pressure pads like these utilizing pressure-sensitive conductive ink. The simple open/closed circuit pads shown here work well above the mattress but (depending on your mattress weight and bed frame structure) can provide false positives when placed below. We had fun stories with our first home testers where many people (me included) planted our elbows and lifted when we turned during the night. This movement was enough of a weight lift over the pad to cause the first iteration of our sensors to trigger. The ability to adjust your bed's unoccupied zero point using an analog measurement, deciding how much weight should be added (or removed) to determine a state change, and over how much time the movement occurred makes a big difference in reliability.

Near the end of my grandmother's life, she was living with my parents and a fall risk. I did this same ESPHome implementation to HomeAssistant to provide us with alerts when she got up on her own in the middle of the night, and it helped my mother sleep much better.

Side note: those other two wires the author says they "have NFI what they do" are most likely wired into the pad as a permanently connected loop. Most monitoring equipment will look for a closed circuit on those wires to detect that a sensor pad is connected correctly and the sensor wire hasn't been broken (ripped, torn, cut, etc).