This is the oxygen gas sensor.
It's used in several of our lab books,
It's used extensively in our biology series,
so the standard biology, advanced biology, the inquiry biology book
And it measures the concentration of oxygen gas in the air.
It's not for dissolved oxygen, so you do not put this into a liquid.
We do have a dissolved oxygen sensor, but it's not this one.
The way this works - It is a chemical half-cell, and it measures the concentration, 0 to 27 percent of oxygen.
The oxygen has to go through a membrane here at the bottom,
so it defuses through there and it can measure that concentration.
One thing about this sensor is that you need to store it vertically.
It comes in this box that says "This Side Up",
and this sensor is in the box in that orientation. it's important that you do store it that way.
The membrane down here, there is a gel that needs to stay across the membrane.
Otherwise, you could damage it if you store it for long term on its side there.
So it's important to be able to do that.
It is possible to calibrate the sensor, though you probably don't have to.
The sensor booklet will tell you how to go about doing that.
Now, the oxygen sensor comes with a Nalgene bottle,
and so this bottle here as the standard one would be in there. So it comes with that one.
Another option though is the BioChamber 250,
and this is a Nalgene bottle with an extra hole for a sensor to go in here.
You might use this in conjunction with a CO2 sensor, so you put the CO2 there and the oxygen there if you wanted to.
I am going to do a little data collection here.
I have some peas which are germinating, and I'm going to put them in the bottle here,
and we'll look at what happens to the oxygen level in this container as the peas are germinating.
To do this one I am going to put the lid on this one,
and then I will put the peas inside the bottle.
I will put the oxygen sensor down into there.
Like that.
And then plug in the sensor.
So when I do this, plugged it into channel one there, it's giving me the oxygen right now in terms of percent.
If you wanted to change those units, it's easy to do.
You tap on the meter itself, you can go into "Change Units" if you would like,
so I could do parts per thousand, parts per million, or percent.
I will leave it just like it is here. We have another option here: you could zero it,
so you could have it read just the change in the oxygen value if you wanted to,
or the calibration you could possibly do if you wanted to, but we will leave that just the way it is.
Now, if you look to the upper right corner there, we'll see our default collection parameters.
The mode is time based, meaning we're looking at the oxygen concentration as a function of time.
The default rate is 1 sample per second, and the default duration is 300 seconds or 5 minutes.
So we are now ready to collect some data, so I'm just going to hit "Collect".
It slides over to the graph, and it's now going to collect data for 5 minutes.
Our data is complete, and we might want to be able to do some analysis here.
If I look at my data, we see that at this first part it dropped fairly rapidly,
because I just put the sensor into the bottle and the peas had been in there just a little bit,
so we saw this drop there.
This last part there looks like it levels off and becomes a fairly linear portion,
and what I would like to do is analyze this section of the data.
So I'm going to highlight that, and I'm highlighting just that region of the graph,
that way when I do the curve fit it will use just those data to calculate that.
So I'll do "Curve Fit",
and then there are little brackets there, and it's asking me that I want to try and use those data.
I'm going to go up to where it says "Choose Fit", and tap "Choose Fit", and I will do a linear fit,
and it looks like I have a pretty nice correlation there, so I will hit "OK".
The slope of that section is displayed there,
so it's telling me what the rate of change is for that piece of the graph.
The oxygen sensor, we have seen, is quite useful. 59 00:05:06:500 --> 00:05:11.000 We used it for the pea respiration here, for the cellular respiration.
We could have used it for photosynthesis,
we could have looked at the oxygen consumption by various animals,
so anything which involves gaseous oxygen, it's definitely good for that.
it's used across the board, and it's definitely a great sensor to have.