They also noted that the reported battery level was not very accurate ... potential water disasters. The Aqara Water Leak ...

Researchers have developed a new optical sensor that provides a simple way to achieve real-time detection of extremely low levels of arsenic in water.

These connect to an LX3302A inductive sensor IC, which reads the position of the copper slug inside the float. That simplifies the process greatly; [Mark] goes into great detail about the design ...