For quite some time the cgallange of high air-humidity or even condensation is known with SDS011 and high fluctuation in reading PM. Every now and then rumers say with SDS030 this problem has been overcome.
Because of law of physics and law of chemistry, I dought the problem has been overcome. What I guess is a calculation to compensate error-reading. This is naturally with cost.
Lets name the facts: In an air-sample-stream of high humidity (>75%) the number of moisture droplets increase rapidely. Where pure gas moisture is not visible, condensed moisture deflect, reflect light. The relation of moisture (ammount of H2O) and temperature determine the dew-point, when the air-body is not capable anymore holding H2O as gas and it becomes liquid as droplets.
Theoretically this is the point, when relative humidity is 100%. In reality, this physical process starts at about 70% Rel-Humidity in a non-linear function. Disturbance is caused by air-polution. Where mineral particles in the size of PM2.5 are very special, particles composed of chemically reactive substances, like sulfious or even more attractive for H2O (NOx), they form clusters. Such clusters not only result in a misreading in number of particles, the error-reading in particle size is obvious.
Heating up an sample-air-stream reduces the ammount of liquite H2O, but it doesn’t reduce the liquite H2O of clusters. The energy applied requires to be much higher, once at all. Applied energy to the air-sample-stream is absorbed by the surfaces in contact with the slip-stream, that is the casing of the sensor as well as the (laser)measuring chamber. Once the surfaces cool the air-sample below the dew-point, condensed H2O forms.
This, and many other aspects more, is why heating the sample is a semi-optimal way. A more promissing way is the absorbtion of moisture from the sample before reaching the testing chamber. This could be done in a combination of chemo-physical process. Material which has a high demand for H2O to ballance molecular grids, like some thermo-dynamically prepared CA[SO4], A theoretical maximum of 2[H2O] ballances the CA[SO4]. Means, for each g of CA[SO4] 2 g of H2O ballances. In reality it is about 1g H2O.
Talking about meta-data for the dehydration, at least this two different methods requires to be identified. Once a drying-chamber is operated, a revolving set of chambers extend the working-phase of the sensor and requires some actor/servo-operation through the firmware.
This is why I mentiond last wednesday the need to decide on sufficient flags and some processing capacity to operate autonomous the dehydration.