Android App to Communicate via Bluetooth to a Microcontroller

Hello, I need an Android app that works as an interface to talk to an external device (could be a microcontroller) via Bluetooth. Have a look at the attached png file. This file shows examples of various screens that would be required. There are a few I've not shown but will be later. The app requires users to input certain parameters (show just 3 parameters here, but need a few more). This could be saved in a program that can be later accessed to be run or edited. During a run, app would pass on the saved parameters to the microcontroller using a certain protocol, that I'll give later. The microcontroller will pass back the actual parameters to the app which the app will display to show the actual parameters (numerically and graphically). Basically, at the start of the run, the app will send temperature 120.0C (for example) to the microcontroller. The microcontroller will read the sensor, switch on the heater, send the sensor reading back to the app, which the app will show. The control action etc. is not the app's responsibility, the microcontroller will do this. The app is just an interface to input and display the parameters. The app should be designed so that its scalable later on. There are going to be different versions of the app, with different parameters (temperature, time, pressure etc.), so adding, deleting these should not be too tough. Let me know if you need further clarifications. Regards, Mohit.