Looking for good gas sensors

Projects General Guidance
1

Hi everyone,

I'm working on a project to measure greenhouse gases in the stratosphere w/ weather balloons, and need some help finding good gas sensors.

I need to detect the following gases - with a sensor for each:

  1. Carbon dioxide (Considering Sensiron SCD30)
  2. Methane
  3. Nitrous oxide
  4. Ozone

Here are my requirements for the sensor:

  1. Temperature - The sensor can withstand up to -67.42°C or at least -20°C
  2. Multiple Gases - The sensor should only detect one gas, not multiple.
  3. Cost - The sensor should cost no more than $100 (This is flexible though)

Your help would be greatly appreciated.

Thanks.

2

Is this just a hobby thing or are you after accurate results?

Gas sensor calibration is VERY hard to accomplish unless you have access to quantities of gas with known concentrations.

1 Like
3

This is for a school project - we're participating in a competition called NASA TechRise.

4

So, actual values are not necessary!

5

Define "good gas sensor", which in this case means defining the range of measurable values and required accuracy of measurements.

$100 per sensor is very unrealistic. For example, methane is a trace gas in the atmosphere, so you would be looking at industrial quality leak detectors for use in harsh environments. Methane Gas Sensor | Best Gas Leak Detection | NevadaNano

6

We do need actual values measured onboard the flight. Here is the competition structure:

  1. We design an experiment proposal (With part list + write-up)
  2. NASA rejects/approves our proposal
  3. We are given $1500 to design our experiment in a box
  4. We ship our experiment to NASA
  5. NASA launches our experiment onboard a weather balloon
7

"Good gas sensor" is defined as:

Accuracy - It should be at least ±100 ppm, preferably lower.
Cost - I'm flexible in this area, I would need to see the options however.

8

So, yes or no. Do you need the sensors calibrated?

9

Currently, methane concentration (by mole fraction) in the upper atmosphere is slightly less than 2 ppm.

To have any chance of winning, you really need to do some very basic research. The judges will instantly recognize and reject those proposals lacking fundamental understanding of the problem.

You have 39 days left.

10

We would need the sensors calibrated if our proposal gets accepted. However, we first want to pass the selection phase, we can worry about calibration later.

11

Ours at work are bump tested daily and then after every use

12

You just can't seem to resist digging that hole you're in deeper!

13

Sorry about the half-baked response earlier, here is the updated accuracy criteria.

  1. Carbon dioxide - ±50 ppm
  2. Methane - Couldn't find any good sensors + specs
  3. Nitrogen oxide - Couldn't find any sensors
  4. Ozone - ±50 ppb
14

Then make a friend with the head of the chemistry department at your nearest university and ask for their help. They will regularly calibrate gas sensors.

1 Like
15

Great! I'll make sure to do that once our proposal gets selected, thanks for your advice. :smile:

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