Additional external sensors for Android?

Question

Android

Is it possible to take a signal from some external sensors, for example
- Magnetic contact sensors (reed switches)
Also, if you know other types of sensors that can be screwed to an Android-based mobile phone - speak.
I want to keep track of parameters (cadence, heart rate, speed, selected gear, moment of pressing the brake) when riding a bike.

Answer 1

developer.android.com/guide/topics/usb/adk.html

Answer 2

With the help of a bluetooth module, a mobile phone can be connected to a microcontroller (for example, Arduino), and already any sensors can be attached to it (reed switches, temperature, pressure sensors, etc.)