{"id":246,"date":"2019-03-19T09:01:53","date_gmt":"2019-03-19T09:01:53","guid":{"rendered":"https:\/\/allabouttheproduct.com\/blog\/?p=246"},"modified":"2019-03-19T09:01:53","modified_gmt":"2019-03-19T09:01:53","slug":"pollution-guardian-measuring-air-pollution-with-cereal-packet-prototypes","status":"publish","type":"post","link":"https:\/\/allabouttheproduct.com\/blog\/startup\/pollution-guardian-measuring-air-pollution-with-cereal-packet-prototypes\/","title":{"rendered":"Pollution Guardian: Measuring air pollution with cereal packet prototypes"},"content":{"rendered":"\r\n<p>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 (NO<sub>2<\/sub>) gas sensors and the type of electronics needed to setup, amplify and filter the output of these sensors. We called it our \u201cbench test\u201d circuit board as we thought it would only get used indoors on the bench..<\/p>\r\n\r\n\r\n\r\n<figure class=\"wp-block-image\"><img loading=\"lazy\" decoding=\"async\" width=\"285\" height=\"331\" class=\"wp-image-247\" src=\"https:\/\/allabouttheproduct.com\/blog\/wp-content\/uploads\/2019\/03\/NO2_bench_board.jpg\" alt=\"\" srcset=\"https:\/\/allabouttheproduct.com\/blog\/wp-content\/uploads\/2019\/03\/NO2_bench_board.jpg 285w, https:\/\/allabouttheproduct.com\/blog\/wp-content\/uploads\/2019\/03\/NO2_bench_board-258x300.jpg 258w\" sizes=\"auto, (max-width: 285px) 100vw, 285px\" \/>\r\n<figcaption>Bench test circuit board<\/figcaption>\r\n<\/figure>\r\n\r\n\r\n\r\n<p>With the bench test board, we designed a couple of options for the electronics solution:<\/p>\r\n<ul>\r\n<li>to provide a backup option, in case the one circuit failed to perform<\/li>\r\n<li>provide us alternate options based on relative performance<\/li>\r\n<li>to enable optimisation of the bill of materials cost<\/li>\r\n<\/ul>\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n<p>Designing &amp; making the circuits went relatively smoothly,\u00a0 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.<\/p>\r\n<p>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 (<a href=\"http:\/\/www.ti.com\/tool\/launchxl-cc2640r2\">TI cc2640R2<\/a>) all contained in a cereal packet wrap for protection. We called our first units\u00a0 Dougal &amp; Zebedee and took them out of the lab and into the car:<\/p>\r\n<p><a href=\"https:\/\/allabouttheproduct.com\/blog\/wp-content\/uploads\/2019\/03\/doug_zeb.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-249\" src=\"https:\/\/allabouttheproduct.com\/blog\/wp-content\/uploads\/2019\/03\/doug_zeb.jpg\" alt=\"Dougal and zebedee prototypes\" width=\"842\" height=\"529\" srcset=\"https:\/\/allabouttheproduct.com\/blog\/wp-content\/uploads\/2019\/03\/doug_zeb.jpg 842w, https:\/\/allabouttheproduct.com\/blog\/wp-content\/uploads\/2019\/03\/doug_zeb-300x188.jpg 300w, https:\/\/allabouttheproduct.com\/blog\/wp-content\/uploads\/2019\/03\/doug_zeb-768x483.jpg 768w, https:\/\/allabouttheproduct.com\/blog\/wp-content\/uploads\/2019\/03\/doug_zeb-624x392.jpg 624w\" sizes=\"auto, (max-width: 842px) 100vw, 842px\" \/><\/a><\/p>\r\n\r\n\r\n\r\n<p><span style=\"font-family: Calibri;\"><span style=\"color: #000000;\"><span style=\"font-size: medium;\">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 NO<\/span><sub><span style=\"font-size: small;\">2<\/span><\/sub><span style=\"font-size: medium;\"> inside the car. <\/span><\/span><\/span><\/p>\r\n<p><span style=\"font-family: Calibri;\"><span style=\"color: #000000;\"><span style=\"font-size: medium;\">The picture below shows a trace of NO<\/span><sub><span style=\"font-size: small;\">2<\/span><\/sub><span style=\"font-size: medium;\"> measurements whilst traversing the one way gyratory system in the centre of Guildford &#8211; note that a decreasing level on the graph trace implies a higher NO<\/span><sub><span style=\"font-size: small;\">2<\/span><\/sub><span style=\"font-size: medium;\"> concentration:<\/span><\/span><\/span><\/p>\r\n<p><a href=\"https:\/\/allabouttheproduct.com\/blog\/wp-content\/uploads\/2019\/03\/Guildford_gyratory2.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-251\" src=\"https:\/\/allabouttheproduct.com\/blog\/wp-content\/uploads\/2019\/03\/Guildford_gyratory2.png\" alt=\"Air pollution on Guildford gyratory system\" width=\"626\" height=\"879\" srcset=\"https:\/\/allabouttheproduct.com\/blog\/wp-content\/uploads\/2019\/03\/Guildford_gyratory2.png 626w, https:\/\/allabouttheproduct.com\/blog\/wp-content\/uploads\/2019\/03\/Guildford_gyratory2-214x300.png 214w, https:\/\/allabouttheproduct.com\/blog\/wp-content\/uploads\/2019\/03\/Guildford_gyratory2-624x876.png 624w\" sizes=\"auto, (max-width: 626px) 100vw, 626px\" \/><\/a><\/p>\r\n<p>&nbsp;<\/p>\r\n\r\n\r\n\r\n<p><span style=\"font-family: Calibri;\"><span style=\"color: #000000;\"><span style=\"font-size: medium;\">So, at the conclusion of our cardboard proto work, we knew we had the right potential sensitivity toward NO<\/span><sub><span style=\"font-size: small;\">2<\/span><\/sub><span style=\"font-size: medium;\"> which we could work with on the next prototype to calibrate and try to get consistent between test units.<\/span><\/span><\/span><\/p>\r\n\r\n\r\n\r\n<p>&nbsp;<\/p>\r\n\r\n\r\n\r\n<p>&nbsp;<\/p>\r\n\r\n\r\n\r\n<p>&nbsp;<\/p>\r\n","protected":false},"excerpt":{"rendered":"<p>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 [&hellip;]<\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[40,44,32],"tags":[],"class_list":["post-246","post","type-post","status-publish","format-standard","hentry","category-iot","category-pollution-guardian","category-startup"],"_links":{"self":[{"href":"https:\/\/allabouttheproduct.com\/blog\/wp-json\/wp\/v2\/posts\/246","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/allabouttheproduct.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/allabouttheproduct.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/allabouttheproduct.com\/blog\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/allabouttheproduct.com\/blog\/wp-json\/wp\/v2\/comments?post=246"}],"version-history":[{"count":10,"href":"https:\/\/allabouttheproduct.com\/blog\/wp-json\/wp\/v2\/posts\/246\/revisions"}],"predecessor-version":[{"id":260,"href":"https:\/\/allabouttheproduct.com\/blog\/wp-json\/wp\/v2\/posts\/246\/revisions\/260"}],"wp:attachment":[{"href":"https:\/\/allabouttheproduct.com\/blog\/wp-json\/wp\/v2\/media?parent=246"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/allabouttheproduct.com\/blog\/wp-json\/wp\/v2\/categories?post=246"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/allabouttheproduct.com\/blog\/wp-json\/wp\/v2\/tags?post=246"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}