In the Air Design Challenge - Pollen & Allergen Sensing – Post 1 (Pollen Sensor)

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In the Air Design Challenge - Pollen & Allergen Sensing

Figure 1. Bad guy (Ambrosia pollen grain)

As I’m still waiting for my challenge kit I’m using the time to consider pollen sensing since that might be the weakest point of my project.

Possibilities

At this moment I have two alternatives for pollen sensor: Homemade and commercial one.

Using commercial one would make my project much easier and the focus would be on making some nice apps for desktop and mobile but with homemade sensor most efforts would be on making the sensor do its thing...

1) Homemade pollen sensor

As my plan is to detect pollen, I did some research and discovered a paper on pollen sensing that proposes an idea which seems feasible (Shigeto Kawashima et al. - An algorithm and a device for counting airborne pollen automatically using laser optics).

This task would require very much hard work and could easily turn out to be a failure but I can still try. Some optics would be required - hopefully I will be able to obtain all the necessary parts to build the prototype.

Figure 2. Pollen sensor

Authors propose that red laser should be used but I think that maybe green or yellow laser would be more appropriate because pollen colour is usually the same (i.e. it reflects green or yellow). I bought the green (532nm) one locally to be used for this purpose.

In order to observe the photodiode sensor signals an oscilloscope is required so I decided to order one that fits in the budget (PicoScope 2204A). It arrived in just two days(!) and as I last used the oscilloscope ~15 years ago (at university) I spend some time testing it – It turned out it’s like riding a bike

2) Commercial sensor

Now some bad news regarding the commercial pollen sensor… The one that I found (http://www.shinyei.co.jp/stc/optical/poln/main_poln_e.html) is not suitable for my location.

It only detects Japanese Cedar and Cypress but these pollen particles are bigger than those of Ragweed (which is the most common allergen in this part of Europe). This is not completely bad news as someone in Japan might find this project useful even with this sensor but for me that's probably not good enough.

Ragweed pollen presence in Europe:

Figure 3. Ragweed pollen presence in Europe (August 2014)

Conclusion

In short, I will most probably focus my work on homemade pollen detection.

I will update as soon as my challenge kit arrives (at this moment it’s being held at the local customs)

Comments and suggestions are always welcome.

Dragan