This semiconductor gas sensor detects the presence of LPG, isobutane, and propane at concentrations from 300 to 10,000 ppm. The sensor s simple analog voltage interface requires only one analog input pin from your microcontroller.
The TMP36G is an analog temperature sensor which has a measurement range of -40 to +125 Degree C.
Unlike all the other temperature sensors we have, this breakout has a really cool IR sensor from TI that can measure the temperature of an object without touching it! Simply point the sensor towards what you want to measure and it will detect the temperature by absorbing IR waves emitted. The embedded thermopile sensor generates a very very small voltage depending on how much IR there is, and using some math, that micro voltage can be used to calculate the temperature. It also takes the measurement over an area so it can be handy for determining the average temperature of something.
The DHT22 (also known by RHT-03) is a low cost humidity and temperature sensor with a single wire digital interface. The sensor is calibrated and doesn t require extra components so you can get right to measuring relative humidity and temperature.