A free app for Android, by NeoFrontier Technologies.

Bluetooth Signal Meter is a handy utility that will help you determine the status of your Bluetooth connection. By using this app, you will be able to detect if your smartphone is connected to a Bluetooth device or not. In addition, you will also be able to check the strength of the signal that is being received. 

The app is very easy to use, and all you have to do is to launch it and wait for it to detect your device. The app will then display the results and will also provide you with information regarding the detected device. You can also check the MAC address of the device and the signal strength.