Monthly Archives: March 2019

Pollution Guardian: Measuring air pollution with cereal packet prototypes

As mentioned in the previous blog, we put in a lot of preparation work over summer 2018 in order to be able to quickly start work on the Pollution Guardian project and de-risk certain areas. One of the first items to be actioned was the creation of a custom circuit board to explore the performance of our selected, affordable Nitrogen Dioxide (NO₂) gas sensors and the type of electronics needed to setup, amplify and filter the output of these sensors. We called it our “bench test” circuit board as we thought it would only get used indoors on the bench..

With the bench test board, we designed a couple of options for the electronics solution:

to provide a backup option, in case the one circuit failed to perform
provide us alternate options based on relative performance
to enable optimisation of the bill of materials cost

Designing & making the circuits went relatively smoothly, but it is not until you receive circuits that you can really see what is going on. Some mistakes we discovered quickly, whilst others took a period to debug. Mostly our mistakes were due to the misinterpretation of and assumptions on the component specifications; our first solutions to these issues actually went on to compound our problems.

After a period of investigation and debugging, we were finally able to identify and solve the underlying issue. As part of this work, we lashed these prototype circuits together with an off-shelf development board (TI cc2640R2) all contained in a cereal packet wrap for protection. We called our first units Dougal & Zebedee and took them out of the lab and into the car:

What we found when we started testing out the units was that whilst our units appeared quite sensitive to temperature change, they were actually capable of detecting low levels of NO₂ inside the car.

The picture below shows a trace of NO₂ measurements whilst traversing the one way gyratory system in the centre of Guildford – note that a decreasing level on the graph trace implies a higher NO₂ concentration:

So, at the conclusion of our cardboard proto work, we knew we had the right potential sensitivity toward NO₂ which we could work with on the next prototype to calibrate and try to get consistent between test units.

Pollution Guardian: From competition win to prototyping

Magic Roundabout characters

Feasibility projects like the Pollution Guardian imply a certain level of risk and it was critical for our business to secure some grant support from Innovate UK to help us mitigate those risks.

Looking back, it seems a long time since we made our application for funding, but considering the risks ahead, we prepared ourselves in order to get started quickly in case of a positive outcome of our bid:

Working on the system architecture, driving decisions on the hardware and software platforms to use within development
Further research on the key components
Talking to collaborators and contractors to re-check availability
Re-planning the market research

Now, many academic papers point to the difficulty in using affordable sensors e.g. around variability, stability and accuracy, so one of our biggest challenges in the project is to put together an affordable solution based on these sensors. Our approach was to tackle this issue head on, building a very early prototype and using a minimum “data gathering platform” around it to understand the pitfalls & performance issues.

This early work cut across several disciplines:

Electronics, designing a custom circuit to best interface with affordable gas sensors
Firmware, building on a development platform to gather and share sensor data over wireless
Mobile app, customised to gather the local sensor data & upload it to a data store
Mobile backend, a real time database to capture the data streams and tools to help explore the data
Mechanics, how to wrap this early prototype for real world use
Early system testing & validation approach

We will be adding a few blogs to the site to cover progress on the above items; suffice to say the first mechanical housing for the unit followed the “breakfast cereal box” approach. After wrapping up the first sensor unit, its looks gave us the name for our prototype, Dougal, after the dog character from the programme, “The Magic Roundabout”.

Origins of the Pollution Guardian Startup

We have now completed the first quarter of the Pollution Guardian project part funded by Innovate UK and it seemed a good time to reflect on where this whole thing came from in the first place.

It all started from a growing awareness, through many stories in the press, about the negative health effects of air pollution. Furthermore this pollution, unlike the ‘pea-souper’ of the 1950s and 1960s was largely invisible. However its immediate term effects were not invisible to the large numbers of people suffering from various respiratory illnesses such as asthma. It seemed there should be a demand to ‘shine a light’ on this pollution.

When starting a business idea it is important not only to understand customer needs but also the business’s capability to do something about it. At All about the Product we are veterans from the mobile phone industry and are steeped in both technical and commercial experience to bring highly sophisticated consumer electronic communications products to market. Any solution we were going to build would therefore be an ‘Internet of Things’ solution.

As many people have told us, for a good product idea it is not only important to know whether there are high levels of pollution present but also there needs to be something to do about it. We therefore became interested in the effects of pollution inside vehicles where there was an opportunity to control this enclosed space more than the entire atmosphere of a city. On further investigation we found articles which showed that very often the level of pollutants inside a car exceed those at the road-side [1] – we had our application focus.

We wanted a product within economic reach of the majority of the population and therefore a low cost consumer internet of things product for use in cars and other vehicles was born.

As this idea developed, we spoke to many stakeholder organisations such as health charities, workers unions, academia and local government. What we learnt from these discussions underlined the fact that there was this invisible problem there and many felt powerless to combat it. Our motivation to do something only grew.

We put our engineering hats and did a quick study to show that producing such a product was feasible. However when we looked at the skills needed to pull this product off, we quickly realised we lacked knowledge about urban pollution and the experience of pollution measurement. Fortuitously our local University – the University of Surrey has a very strong department in this field, so we contacted Professor Kumar at the Global Centre for Clean Air Research (GCARE) and set up a meeting. It quickly emerged that our skills complemented those of the university in making this product investigation happen. We agreed to join forces in making a bid for one of Innovate UK’s competitions and after a couple of attempts we won one! Thus the Pollution Guardian Project was born.

[1] Cepeda et al :Lancet Public Health 2017; 2:e23-34

https://allabouttheproduct.com/

https://www.surrey.ac.uk/global-centre-clean-air-research