[HN Gopher] Smallest particulate matter air quality sensor for u...
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Smallest particulate matter air quality sensor for ultra-compact
IoT devices
Author : Liftyee
Score : 155 points
Date : 2025-07-27 03:34 UTC (19 hours ago)
(HTM) web link (www.bosch-sensortec.com)
(TXT) w3m dump (www.bosch-sensortec.com)
| arnejenssen wrote:
| Cool. So we could get air quality apps for the phone or
| smartwatch?
| mjs wrote:
| Might need to wait a few generations. It costs ~30EUR for a
| single unit (maybe half that at volume?). And not waterproof.
| progbits wrote:
| It needs an external lens anyway so you could shove it into
| the camera assembly, waterproofing is not an issue.
|
| Cost is one, but this isn't something you can measure quickly
| on demand, you want to keep averaging multiple measurements
| over time. So unless you want to hold out your phone for
| minutes to get a measurement it doesn't seem practical.
| user_7832 wrote:
| Where did you see 30 euros? If so that's quite good I think -
| I remember (a long time ago when I was researching air
| sensors) Honeywell's laser sensors were similarly priced. A
| low price point will absolutely help Bosch drive adoption.
| mjs wrote:
| Re price, there's links to retailers from
| https://www.bosch-sensortec.com/products/environmental-
| senso...
| shagie wrote:
| Chasing through to https://www.bosch-
| sensortec.com/products/environmental-senso...
|
| > Discover the PurpleAir PIXEL, one of the first end devices
| featuring the BMV080 particulate matter sensor for precise
| local air quality measurement. This user-friendly device
| provides real-time PM2.5 readings with a quick response time,
| clearly displayed via LED indicators. The BMV080's fanless
| design ensures completely silent operation, making it both
| effective and unobtrusive.
|
| https://www2.purpleair.com/products/purpleair-pixel
|
| That's the form factor you'd be looking at when its included
| with the rest of the supporting circuitry and logic.
|
| So... possibly might be able to get it into a smaller package
| if the data display is externalized (Purple Air uses LEDs).
|
| My parents are interested in this as one of their use cases is
| to put it on their e-bike so that they can be made aware of
| worsening air conditions after they've left the house.
| 9dev wrote:
| Waiting for Achim Haug of AirGradient! What's your thoughts on
| this?
| ahaucnx wrote:
| Hahah. Thanks for calling me!
|
| We actually have a sample of the Bosch in our office but
| haven't come along to test it yet. Maybe with this call, I will
| get our team onto it.
|
| The form factor has pros and cons in my opinion. The size and
| lower energy consumption definitely opens new applications but
| the problem is that it needs a clear field of view to do the
| measurements.
|
| This could in turn restrict the applicability, eg as a wearable
| sensor.
|
| In general I think it's great to see innovations in the PM
| sensor field but often minimizations go on costs of accuracy.
|
| We saw that for example with the Sensirion photo acoustic CO2
| SCD4x sensor that is tiny but needs more black box algorithms
| to compensate for certain environmental conditions that then
| limits the range of applications.
| mrlonglong wrote:
| Airthings View Plus is PS250!
| Liftyee wrote:
| Interesting points - I wasn't aware of the accuracy tradeoffs
| with smaller sensors, though as an engineer I should probably
| have anticipated it.
|
| I've been messing around with air quality measurement for a
| while but haven't got anything for the day to day yet.
|
| Been a long time admirer of the Airgradient project. What are
| your thoughts on the SEN5x Vs Plantower PM sensors?
| ahaucnx wrote:
| We don't have enough experience with the SEN5x yet to give
| an opinion but it's definitely a good sensor.
|
| It might be better than the Plantower but on the other hand
| we know the Plantower really well now after 10s of
| thousands of units going through our test chamber. This
| allows us to tweak the Plantower to really good
| performance.
| westurner wrote:
| I was looking at Radon sensors the other day. FWIU it isn't
| possible to detect radon with even a PM 2.5 sensor.
|
| I bought a 10-in-1 air quality sensor with USB-C, and it
| won't do USB-C PD.
|
| Batteries for when the power is out make sense.
|
| Which air quality sensor integrates the most sensors of all?
| noahjk wrote:
| Does the "Everything Presence One" and (hopefully) upcoming
| Pro model fall under things you review? Any thoughts on how
| it stacks up for a smart home device?
| ahaucnx wrote:
| Can you please clarify what you mean with "Everything
| Presence One" and the "Pro Model"?
| alliao wrote:
| love this... while the politicians busy angle themselves over
| stances on whether air filtration is required for public space
| during a pandemic engineers and companies come up with products
| and solutions ready to deploy.. it is my dream that our last
| generation gave us clean-ish water, and we can somehow pass down
| clean-ish air...
| zevon wrote:
| Does anybody know how they actually do it without a fan and a
| defined volume around it? The marketing fluff says "It applies
| sophisticated algorithms to measure the PM2.5 concentration
| directly in free space, without requiring a fan", so I assume the
| main difference to traditional PM sensors is the software?
| trailbits wrote:
| Also wonder how the sensor can stay clean without a fan. I
| suppose mounting upside down would help. Other fanless designs
| require periodic cleaning.
| dist-epoch wrote:
| The integration picture shows an "optical cover" transparent
| surface. I guess it's not meant to be used in highly
| contaminated areas.
| dist-epoch wrote:
| They have some tech specs: https://www.bosch-
| sensortec.com/media/boschsensortec/downloa...
|
| > Laser light is emitted from the sensor and focused by the
| sensor lens at approximately 5 mm from the top of the sensor's
| lens surface.
|
| > Particles traveling in free space due to the natural ambient
| airflow are detected when passing through the laser focal
| (sensitive) region.
|
| > Due to the interaction between particles and light, the light
| scatters in different directions; a fraction is back-scattered
| towards the sensor, where the integrated photo-detectors detect
| it.
|
| > The back-scattered signal is processed by unique algorithms
| (based on particle counts, particle relative velocity, probed
| air volume during measurement) to derive the particulate matter
| mass concentration.
| trailbits wrote:
| That's pretty much how all laser particle counters work...
| except the good ones use a fan and a chamber. Guess we'll
| have to wait and see how this compares to the reference
| sensors.
| ImaCake wrote:
| Yep, I suspect this is all marketing fluff and no
| substance. I see a lot of superlatives but no substantial
| technical breakthrough here.
| f1shy wrote:
| I'm pretty pretty sure it is just marketing
| hakonjdjohnsen wrote:
| I think there is at least some plausible interpretation
| of this that points to more than marketing fluff.
|
| You want to count particles per volume of air, so
| conventional sensors use a fan to have a constant
| volumetric flow and then count particles per second to
| infer particles per volume.
|
| The way I interpret the above marketing language is that
| they use the optical sensor not only to count particles
| but also to measure the particle movement and infer
| airflow. So as long as there is some natural movement in
| the air, they can measure both particle count and
| volumetric flow, and thus infer particles per volume.
| TimByte wrote:
| My guess is they're relying on natural air convection and using
| a more sensitive optical setup to compensate for the lack of
| forced airflow
| f1shy wrote:
| They don't give lots of heat, so convection is negligible.
| f1shy wrote:
| Lying?
| rurban wrote:
| Marketing. Still a good sensor, just not as good as the ones
| with a fan. We didn't use this one
| ethan_smith wrote:
| These fanless PM sensors typically use thermal convection to
| create natural airflow across the sensing area, combined with
| advanced signal processing to compensate for variable flow
| rates and environmental conditions.
| smingo wrote:
| The entire device is tiny: 20mm x 5mm x 5mm approx. It looks to
| work using a small laser and a lens which focuses the beam about
| 5mm above the device. The sensor unit contains a photodiode(s),
| and algorithms count the particulates. It looks to need a heat
| sink.
| pppone wrote:
| I've been running multiple Sensirion SPS30 PM sensors for years,
| and I'm honestly amazed how well they've held up. Particularly
| with respect to, within their spec'd error, how new/unused SPS30s
| report similar values to my heavily used ones.
|
| Curious if there are any maintenance requirements for the bosch
| sensor.
| quickthrowman wrote:
| Do you actually do anything with the data you collect?
|
| As someone who manages commercial building automation system
| installations, I have never understood the obsession that HN
| has with residential IAQ sensors. The number will go up if you
| cook, burn a candle, use a hairdryer, or if there's wildfire
| smoke outside and you have a ducted HVAC installation with an
| outdoor air intake.
|
| In a commercial BAS, IAQ sensors (CO/NO to be more specific)
| are used to turn on exhaust and make-up air fans to increase
| the air quality in a space, but in every single thread about
| IAQ monitoring on HN, nobody ever seems to use the sensor
| readings to automate their HVAC equipment to do anything. In
| fact, almost all commercial BAS systems have zero IAQ sensors
| (especially in offices), the vast majority of them are use for
| turning on exhaust fans and make-up air units in buildings
| where cars are driving inside, like a parking ramp or drive-in
| warehouse.
|
| I guess my question is, why collect this information and do
| nothing with it? Maybe you actually do something with it, or
| you monitor local outdoor air quality as a hobby. I'm asking a
| more general audience than you specifically.
|
| Lastly, ensuring your house is positively pressurized by paying
| a testing and balancing contractor to come over and adjust your
| HVAC system will do more to keep out particulate matter than
| measuring it ever will.
| shawabawa3 wrote:
| I use it to send an alert when CO2 is too high too open some
| windows
|
| I live in an old 1930s house in the UK so no HVAC or anything
| more automatable sadly
| macNchz wrote:
| I bought an Awair device in 2020 when my wife and I were
| working from home full time in the same room, out of
| curiosity as to whether our office area air was accumulating
| lots of CO2 during the workday (turns out this is not really
| an issue in drafty 120 year old houses).
|
| In the time since I've found it helpful for: confirming my
| DIY air purifier was effective during wildfire smoke periods,
| having a reminder to open the windows generally when the air
| gets stale and particularly after cooking, learning that
| cracking a window for makeup air for the range hood makes it
| much more effective, getting better about trimming candle
| wicks and snuffing them instead of blowing them out, getting
| a sense of our actual temp and humidity comfort ranges and
| how they differ from thermostat settings, and realizing that
| induction really might be preferable to gas whenever we're
| looking to buy a stove in the future.
| pppone wrote:
| I used to run https://www.open-seneca.org/. But, personally,
| it's nice to know the PM value whilst cooking, before going
| on a run, etc. Permits you to take informed decisions.
| Implicated wrote:
| I use co2 measurements in my home to do just what you're
| describing here - automate control of a DIY fresh air intake
| (through a custom built filter box/fan enclosure w/ 5" merv
| 14 filter).
|
| It's rather dumb at the moment, but when number gets too
| high, it kicks on for 1 hour and if it's back below threshold
| it shuts off. There's also a human presence detector that
| will "pause" it for 5 minutes since it's in my kitchen
| window.
|
| It's built out of cardboard (laminated, with wheat paste) as
| a proof of concept/tinker with design and placement of things
| and also serves as a platform for the cats to nap in the
| window.
|
| This, mainly, helps from bringing in all the outside humidity
| during the summer and the bitter cold during the winter.
| Otherwise, prior, I'd just keep an exhaust fan running all
| the time (eating the losses on air conditioning/heat) but
| we'd end up closing the window when it was super hot/cold and
| then the iaq would get terrible.
|
| Lots and lots of people are automating their various systems
| due to monitoring these values. An application I've seen lots
| of is to just kick on the hvac systems fans when the aq drops
| below a particular threshold in one room or another.
|
| > Lastly, ensuring your house is positively pressurized by
| paying a testing and balancing contractor to come over and
| adjust your HVAC system will do more to keep out particulate
| matter than measuring it ever will.
|
| Sadly, it took me a while to figure out that having this
| window fan in my kitchen on "exhaust" rather than "intake"
| was creating a negative pressure environment and that was..
| not optimal.
| bobmcnamara wrote:
| What's your measurement reference? Canned?
| pppone wrote:
| We've colocated many SPS30s with government reference
| stations, and the low cost sensor have always performed
| relatively well. But, more importantly for my use case, they
| are exceptionally inter-comparable.
| Catbert59 wrote:
| Many particle sensors are useless in foggy/hazy conditions, which
| ruins many citizen science projects in terms of data quality.
| Currently, the best solution is to calculate the dew point and
| then switching them off once you hit a specified limit.
|
| How does this model deal with this?
| pppone wrote:
| I don't think it would. Data in these instances would have to
| be ignored.
|
| You can detrend for high humidities, but once water condenses,
| the only way round this would be to add a drying instrument.
| HPsquared wrote:
| I wonder if a radiant heat source beside the sensor, maybe
| also somehow focused in the same area, could get rid of the
| condensed water.
| Catbert59 wrote:
| The problem is not condensed water. This can be solved with
| heating.
|
| It's that fog is being detected as a particle. This
| distorts the measured values.
| HPsquared wrote:
| Fog is condensed water droplets suspended in the air.
| Radiant heat , especially if it's optically focused,
| could remove them in the area where the PM sensor is
| looking.
| TimByte wrote:
| I didn't see anything in the article about humidity
| compensation
| progbits wrote:
| I mean this is cool but the size claims are somewhat misleading.
| They only sell you a sensor element on flatflex PCB, then you
| need to add own metal cage for thermal dissipation and a lens, so
| the overall size is significantly larger.
|
| This is great for flexibility but very impractical especially for
| DIY space. Hopefully small fully integrated modules on something
| like edgeconnector PCB come out soon enough.
| joshvm wrote:
| Unless I misread, the lens is integrated, but Bosch recommends
| an optical window to protect the device. The integration guide
| is pretty comprehensive. Many fan-based air sensors require
| some specific enclosure considerations to separate the
| in/outflow.
|
| Sparkfun sell a module with a ground plane + thermal pad as
| heat sink. This is suggested as OK by Bosch, though adding a
| small heatsink is probably a good idea, or just mount the
| enclosure on a metal surface.
|
| https://www.sparkfun.com/sparkfun-air-quality-pm1-pm2-5-pm10...
|
| https://www.bosch-sensortec.com/media/boschsensortec/downloa...
| progbits wrote:
| Ah I was looking at the integration guide but just skimmed it
| and I thought the window was a required lens. Thanks for the
| correction. (Can no longer storage edit my comment
| unfortunately)
| TimByte wrote:
| The fact that it's fanless and still works reliably makes me
| curious how well it handles airflow variability in real-world
| settings though
| SideburnsOfDoom wrote:
| FYI, it is a "Smallest sensor, for particulate matter", not
| "sensor, of Smallest particulate matter"
| benbojangles wrote:
| What use case would miniaturisation of dust sensors have, i mean
| i am unsure if it is going inside smartphones or smartwatches?
| What can it do that others cannot?
| ck2 wrote:
| I wish everyone had an air-quality sensor on their smartphone
|
| it might make people give a darn how bad it typically is
| everywhere now
|
| But won't trust this sensor until there are tech comparisons by
| AirGradient and BreatheSafeAir.com
| dzhiurgis wrote:
| Wish macbooks came with air sensors. Already has a fan, on when
| you use it can be woken up every 5 minutes if you need continuous
| monitoring.
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