The Smoke SnifferTM
is the name of a robust, portable, and accurate particle detector, which measures small airborne particles.
It is currently being developed by Gerard Harbers and Herman Schaap, two Dutch-American engineers living in Northern California.
Its goal is to measure the airborne small particles in the field, and give direct feedback on the air quality as concerned to small particle count.
So that you know if it is safe to work or exercise outdoors, or when you need to use a mask, or — just stay indoors, with or without a mask.
These particles are produced for example with combustion engines (especially diesel), but in particular with open fires.
The SmokeSniffer is currently in development.
First prototypes are available soon for demonstration.
We expect to be able to supply these in larger quantities before summer, before the wildfires season starts again.
Why are we developing the Smoke Sniffer?
Late 2018, fires in Northern California caused poor air quality in much of the state.
Air quality is monitored in the United States by the Environmental Protection Agency,
and their data is reported on the AirNow Website.
When we had these bad conditions, I (Gerard) noticed that the air quality values could change rather quickly,
and that the forecast was not always correct.
And when I thought the air quality was good enough to do some work on the yard, based on the data of the website,
I noticed a couple of hours later that the actual air quality had been poorer than expected.
One problem with the official numbers is that the Air Quality Index Numbers are average over a period of 24 hours —
which might be good enough for country and state wide averages:
but not in case of wildfires, or local sources of pollution, which can occur much quicker and can be so localized,
that it will take a while before they show up in an official monitor station.
Frustrated by this, I looked online for relatively low cost, robust, portable, and accurately calibrate particle detectors,
so that I could get instant feedback on the air quality in my location.
And I could not find anything...
At least nothing that I really liked.
Being an engineer and an inventor, I decided to make it myself.
First I started looking for particulate matter sensors — the basic component used in a more generic air quality control products such as air purifiers.
These sensors measure the small particles that are the major source for bad air quality under smoky air conditions.
I checked many, and eventually made a choice, and ordered a couple.
The project stopped for a while, as I went on a vacation.
When I talked about the project with Herman Schaap when we returned from vacation, he motivated me to accelerate the project.
In the area where he lives they have a lot of burns, and he was very interested to use such a device to check the current air quality in their area with regard to smoke.
Together, we got started to make prototypes of actual devices, using a 3D printer.
This is currently still more or less a hobby project, and we are still in the prototype phase.
We are making fully functional prototypes though, and if you are interested and want to buy one of these and help to test them, please let us know!
We can only get this right with your feedback!
Just send us a note in the Contact Form, and we will contact you with more information.
The sensor used in the Smoke Sniffer is produced by Honeywell: it has the product code HPMA115S0-XXX and here is a link to its datasheet.
It measures both the PM2.5 and PM10 levels (this will be explained later on this page)
using a laser, a detector, and the principle of laser scattering.
This is a very sensitive method which measures the individual particles, and is a true particle counter.
The sensor has a small fan which sucks the air from the environment and leads it along the laser.
If there are no particles in the air, the laser light will not be interrupted and the detector under the laser beam does not detect any light.
Particles in the air, however, will scatter the laser light in all directions, and some of this light will fall on the detector and gets detected as a pulse by the on-board electronics.
The more particles, the more light pulses gets detected
The sensor has a measurement range from 0 to 1000 µg/m3, and has an accuracy of ±15%.
First I thought the sensor would be too big, but looking at the dimensions I thought it might work for my purpose.
And the operating temperature range, and the fact that it is fully calibrated by Honeywell, made me to proceed with this device.
It has a relatively fast response time of six seconds, and a whopping rated life of 20.000 hours,
However, the sensor as such provides only raw data over a serial port, and also needs to be powered.
It has no battery, and no means to report the result in direct visible form.
It also does not report the Air Quality Index directly: it reports the PM2.5 and PM10 levels particle count levels. which need to be scaled to give a single Air Quality Index Value.
It is intended to be used as part of another product, such as HVAC systems, air cleaners (at home or in your car), and environmental monitoring.
So we needed to add a housing, which would have a microcontroller board, a small battery, and a way to present the measured results instantly, in an accurate and easy-to-understand way.
Herman and I started working on the housing design directly after Christmas, using a CAD program, and my PRUSA I3 MK3 3D printer, shown here on the right.
We quickly prototyped and rejected 4 to 5 designs.
We wanted it to be as small as possible, with a minimalist, functional design.
We also wanted it to be relatively portable, and being able to measure air quality by sticking the sensor in the air, in an area where smoke is visible,
or measuring lower at the ground, without having to reach low.
So we thought it would be good to be able to put the device on a monopod, as for example used with the currently popular GoPRO camera.
And — for branding and marketing purposes — we needed a spot to put a product label.
After many iterations, we ended up with in total four parts, as shown at the picture above.
We chose the color orange, the familiar "warning" color.
The parts are:
The base plate, which attached to the mono-pod (upper left).
We chose a mount similar to the one which is used with GoPro cameras.
This is a solid, and low cost mount.
The housing, which holds the battery and electronic components (not shown).
A cable cover, which is used to cover the cable which runs from the electronics housing to the Honeywell connector.
This is shown here attached to the left side of the housing.
A brand cap, showing the "Smoke Sniffer" logo in black letters on an orange plate,
attached to the top of the Honeywell particle sensor.
Electronics and Instant Air Quality Indication
Next the electronics, which reads out the data from the Honeywell particle sensor, and calculates the Air Quality Index.
It indicates the current air quality using a colored LED, with colors same as used in the EPA's AirNow website, varying from green for good air quality,
to purple for very unhealthy.
AirNow uses a brown color for the "Hazardous" level: brown is not a very good color to display with LEDs, as it is a sort of dark orange.
This is hard to distinguish from orange and red.
For the Smoke Sniffer we chose to use blinking purple for the "Hazardous" level.
Internally We are using two boards, a battery, and an LED to generate the colors for these different Air Quality Levels.
If you want to keep updated, and maybe also want to be one of the first customers for a Smoke Sniffer, please use the form below.
Depending on your interest, we will contact you using the provided email address when and how you can obtain a Smoke Sniffer.
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- The first board is a microcontroller board.
This board communicates with the Honeywell sensor using a serial interface.
And it has a USB connector to connect the SmokeSniffer to a computer, in case you want to get more detailed information from the sensor.
We are using an Adafruit Trinket M0 board here, and an Arduino programming environment to program it.
The second board is the battery charger and sensor power board.
The SmokeSniffer has a battery, which is charged by connecting it to a USB charger.
This board charges the battery under the right conditions.
The board also has a boost converter, which transforms the battery voltage to a 5V voltage, which is needed by the Honeywell sensor.
We could not find a board which was small enough, and did what we wanted it to do, so we are making this board ourselves.
Currently the boards are being made, and we are waiting to get the boards back and start assembling and testing them.
For the battery we are using a small LIPO battery.
We did not do the testing yet with this battery, as we are still waiting go get the charger board up and running, but we expect the battery to be able to power the sensor for an hour or so.
Typically you would use the SmokeSniffer only for a minute or so, to quickly check the air quality.
You press a button on the Sniffer, and it will indicate the status by the LED color.
If you press the button again the Sniffer will switch off.
In case you forget to switch it off, it will switch off automatically after 5 minutes.
If it is attached to a computer, the Sniffer will remain on, and will run from the power provided by the computer through the USB board.
For the Air Quality Feedback an multi-color LED is used.
The microcontroller board as produced by Adafruit has a built-in RGB DotStar LED, capable of making all the colors we need.
Instead of using a separate LED, we decided to use this onboard LED, and use an optical light guide to bring the light out to the edge of housing.