There are many ways to go for Wireless parti wish to build a wireless gas leakage detector..
anyone have idea about the wireless part?
For Transmitter sideblueroomelectronics,
i think i would try the simplest fm transmitter
For Transmitter side
give the output of gas sensor to microcontroller.
then give output of microcontroller to DTMF encoder
DTMF encoder output is given to FM transmitter
For Receiver side
FM receiver output is given to DTMF decoder
then give output of decoder DTMF to microcontroller
give the output of microcontroller to buzzer or display
or else you can give output of decoder directly to buzzer
Please let me know if you need any more help