This is a great device for developers with an idea! A little pricey now, if it catches on that will change. You can hook up motors, solenoids, sensors, etc. directly to pins , no interface circuits needed!
To build this LPG gas leakage detector using arduino uno, we used a LPG gas sensor module to detect LPG Gas. When LPG gas leakage occurs, it gives a HIGH pulse on its DO pin and arduino continuously reads its DO pin.