Environment Monitor
Personal Project
Present
This is an active project that I'm working on in the background. It's not fully completed, and therefore has not been through the whole product development process.
The Idea
The inspiration for this project came from a personal experience. I was using a table saw to cut 4' x 8' sheets of MDF down to smaller sizes that I could then laser cut. After ripping through a couple of sheets, I noticed that the air started to almost feel thick and there was a slight haze throughout the room. Taking a second and thinking about it, I realized that not only should I probably have some breathing protection, but also hearing protection.
Understanding when to wear PPE such as respirators or earplugs can be challenging in a wood shop environment, especially for beginners who are less familiar in such an environment and don’t understand the repercussions. To that end, I wanted to work on a product that could monitor the current air quality and noise of its environment and relay that information in a visual manner.
Develop a device to inform people of the current air quality and volume of the environment around them, giving the information needed to make more informed decisions about whether to be wearing PPE.
Breadboard Prototype
Before anything else, I wanted to put together a quick breadboard prototype to understand what sensors would need to be included in a final product. I had just bought a Raspberry Pi Pico recently and decided to use it for this project since I intended to upload the data online for remote storage. I also already had the microphone breakout and the two 8-pixel LED strips. I did not, however, have the air quality sensor, specifically an air particulate sensor, and ended up purhcasing a pre-existing sensor (the blue box in the picture above).
I wrote the code for this project in Circuit Python and used Adafruit IO to upload readings to the cloud. I used the shown scaling system on the left to highlight how the level of the current environment was. Additionally, if either reading stayed above the safe threshold for over 10 minutes, a notification would be sent to my phone via the Pushcut API.
A quick aside: I know that solely measuring particulate in the air is not a holistic means of sensing air quality. Given that at this time the scope was mostly focused on dust in a wood shop and that this was a quick prototype, I continued just with particulate measuring.
It Should Be Smaller
After finishing up the code and having the breadboard prototype sit in the shop for a couple of days, there were a few shortcomings that I noticed:
- You have to make an effort to look at it while working or else it fails to relay information about the environment.
- Room readings aren’t always representative of the air quality and noise levels someone in the room could experience. For example, when soldering, the fumes are highly localized, so the device might not capture them if it's too far away. Similarly, sound intensity decreases with distance from the source.
Because of these two things I knew that I ultimately wanted to shift the project into being a wearable device. Having it be a wearable also opens up the potential for this to become a device that could be used throughout your day and in every environment. It could, for instance, help gauge local air quality outdoors or monitor noise levels in a train or during a flight.
Develop a device a wearable to inform people of the current air quality and volume of the environment around them, giving the information needed to make more informed decisions about whether to be wearing PPE.
Calculating Air Quality using Position Tracking (In Theory)
Wearables inherently need to be small devices. If they get too big they become cumbersome and no-one will wear it ultimately making it pointless. And while most of the internals can be significantly shrunk using things like a MEMS microphone and custom-PCB, shrinking the air particulate sensor is a challenge.
Air particulate is measured by using a laser and counting how many times the beam is interrupt by small particulates. To take that count and translate it into actual measurements though, it needs to understand the volume of air that passed by the laser in that given time. To accomplish this there are two common methods: using a fan to push air at a constant rate, and using a heating element below the laser that ends up moving the air as it heats up and rises. Both of these have trade-offs that quite frankly don’t make them ideal in a wearable: the fan is large and makes the product big while the heating element approach is much smaller but only works in one orientation.
This is where my idea come into play.
I am currently in the process of trying to design a means to test this, and therefore is completely just a theory at this point in time.
Rather than using a fan or heating element to move area through a laser that is assumed to be stationary, what if you could understand how the laser is moving through the air while on your body, and therefore the volume of air that is encounters at any given time? This would get rid of the bulky fan while also allowing the device to work in any orientation as long as it is moving in space and has clear access to the air around it.
Sketching
Besides the internals, I have started doing some quick sketches of different forms that the wearable device could take. Below are pages from my notebook of different sketches with purple highlights for the concept that prefer and plan to make quick CAD models of that I can print and interact with.