i must do something with these matereals(sensor+arduino only)
Well, sensors by their very nature don't "do" anything, they "sense".... then you need an actuator to be the "do-er" based on what you sense. For example, you have a temperature sensor you say: well there's no point measuring the temperature if you don't act on that reading, eg switch the fan on if it's too hot.
But remember the Arduino has a built-in LED on pin 13- perhaps you could make that do something based on the readings