I need to know how hard will it be to get input from a heartbeat sensor connected to arduino to a android running a unity made app. Im making for my degree final project a vr system that take a real time heartbeat input to effect the unity game, and i need to decide if i want a simple android vr or oculus (which is less common and more expensive). The plan is to connect the arduino via usb and call the serial port, but i think it may be more complicated then that. Since I have no prior experience in arduino i would love to get your advice in what I will need to do to make it work.
The easiest way is to send the collected data through Bluetooth controller. You can buy an HC-05 Wireless Bluetooth Serial Transceiver Module for 3 US dollars. You can connect the device to Rx and Tx terminals on Arduino. See this link for details on how to use HC-05 with Arduino.
In android device side Install or create an android application which can send data through Bluetooth serial terminal. You can find lot of BT serial port terminal applications in play store. I think some of the applications are open source and you can use their code in your own application.