When we are building our prototypes, we want to provide the best possible interaction for our final users. Sometimes, we build real-world applications that don't have any human interaction but they simply listen to the environment to collect data and decide what to do. Whatever our prototype, if we want to read and understand human actions or environment changes, we need to use a new set of electronic components: sensors.

Every time we build a physical application, we have to bear in mind that the more complex our project is, the more likely we need to add sensors to achieve the desired interaction.

In this chapter, we will start a new real-world application from scratch that is capable of sensing our heartbeat and publishing the result to our Android application.

In this chapter, we will cover the following topics: