Meet Elephant Door: a smart home security system that alerts you when someone attacks your door. It has an accelerometer, gyroscope, and microphone for precise detection. Just attach the device to your door, and you will get notified upon a break-in attempt. Elephant Door can sound a 100+ dB alarm.
Elephant Door uses sound, vibration and motion algorithms to detect attempted break-ins. It has a sleek design and mounts to your door conveniently. Elephant Door is compatible with iOS and Android devices.[Source]