The Notion sensors for smoke/ CO, water leaks, temperature changes, and entryways are wireless, peel-and-stick sensors that work by connecting to a bridge over Wi-Fi. That bridge connects to the Notion Android app or the Notion— Home Awareness iOS app so users get notified when alarms go off. Unlike most sensors, Notion’s sensors are multifunctional, so you can detect more information without buying more sensors. However, as Notion doesn’t offer cellular or landline backup, if your power or Wi-Fi falters, you may lose connection to your sensors.