Mindboards

hi all
i'm new member here in this great forum

i'm trying to build my first robot (chemical robot) that can detect if any toxic gas and sends alarm to alarm students in lab to take the safty rules if they not do

can anyone give me a suggestion and comment about this idea and what sensors i need to use ?

wait your response as soon as possible becouse it is a part of My seior project

thanx

You need a gas sensor. You never told us what gas it needs to sense. There are no gas sensors that I know of that will work directly with the NXT, but with a little circuit, it should be pretty easy to get most sensors to work with the NXT.

Vernier got lots of scientific sensors and a sensor adaptor to NXT:
http://www.vernier.com/probes/index.html
http://www.vernier.com/nxt/

They do have a lot of really nice sensors, but they cost a TON! What I was thinking, was something more like a <$10 sensor, plus the circuit needed to interface to the NXT.

Here's an idea... If you want to detect a gas leak , then you could use some sort of pressure sensor in the piping.
Also, if this not just a proof-of-concept, and you plan to actually use it, then you will need a rechargeable battery pack.

really thanx all for replaying
the main project objective is increasing the safty in chemical lab but till now i'm not decide exactly which toxic gas i will detect
(i'm thinking to detect NO2) .

I actually found one - not nearly as expensive as I thought:
http://www.produktinfo.conrad.com/daten ... AS_MLN.pdf

SparkFun has a fairly good assortment of gas sensors. Only about $6 with the breakout board! They do need a 48 hour "break-in" time before you use them but once you do that they do seem easy to use. You'd only need a couple resistors and the breakout board (although even that is optional) and they seem to have good response time. A couple downsides though. You can't detect gas if it's on the other side of the room. You'd need a way to make sure you could reliably detect the gas, every time. Also, one person complained that once the sensor does detect gas, it takes a while for the sensor values to drop back down. Could just be one incident though.

Also notice a couple other things. Current draw is very high, upwards of 150 mA as far as I could see. Also, they run hot as they sense gas with a heated element. Just some things to think of. Also, as I've said before, I don't work for SparkFun, just a happy customer. [LINK]

thanx all you really sharing other your Knowledge
i will start reading in detail about these sensors
but does anyone has more ideas to increase the safty in chmical lab ?
i'm a computer science student so my knowledge in hardware is not very good
plz advice me is this idea is good to be senior project ?

Well, to increase safety in the science lab, you could attatch a robot to everyone's lunchbox, an RFID tag to detect when in the science lab, and it could detect when the lid is open and set an alarm off to enforce the 'no eating' rule. JOKES!