Inspiration

The world faces three major challenges: COVID-19, Global warming, Pollution. What could we offer to help? Our idea stems from the economic and social impacts of COVID-19, as well as concern over an increase in single use plastics.

To brainstorm, we did research on our own and watched documentaries from PBS. It was eye-opening to see the devastating effects of single use plastics on our world. To help, we wanted to both find a way to limit plastic use and contribute to the efforts against COVID-19.

Our idea came from considering the produce you buy in store. When looking into this, we came across some ridiculous products being sold.

Plastics can easily offer a promise of sanitation, but could there be a better way? This is the question we asked ourselves, and we came upon the idea of sanitizing with UV light. We wanted to give customers confidence that their foods were virus free without the use of plastics.

We came up with a device that disinfects groceries at the checkout as the cashier scans them. It is a cheap, quick method of reducing contamination risks for buyers.

What it does

COVID-19 has reduced consumer confidence in public safety. People are shopping less, and people are buying fresh produce less. https://foodinsight.org/wp-content/uploads/2020/04/COVID-19-Consumer-Research.April2020.pdf https://www.thepacker.com/article/40-shoppers-report-changing-produce-purchases-due-coronavirus

People are also buying more packaged goods, making the single use plastic issue we are facing even worse. Our goal is to increase consumer confidence in shopping, to reduce contamination from grocery shopping, and to increase consumption of fresh produce that are not housed in single use plastics.

COVID-19 contamination can be caused by contact with surfaces. COVID-19 can live on surfaces for up to 3 days, so groceries and produce shoppers take home could be contaminated.

As well as food being an issue, conveyor belts in grocery stores are rife with bacteria. They are porous, making them dirty and not sanitary. Our device will also act to sanitize the conveyor belt itself, further increasing food safety.

How we built it

What bulb should we use?

Bulb: TUV PL-L 36W/4P This bulb is a UV-C type. This means that its wavelength is in the range of 100 - 280 nm. This bulb emits light with a wavelength of 254 nm.

Source: link

Cost: 15 Dollars each or 289.95 for 25

Source: link Source: link

Wavelength: 254 nm

UV Intensity: 12 W

Dosage = (UV Intensity / m^2) * t

Dosage: (12/(0.3)^2) * 10 = 5813 J/m^2

Can it kill COVID-19? What can it kill?

We chose this wavelength because it is capable of disinfecting. It has been shown that UV-C is able to combat bacteria and viruses: Source: link

UVC light has been shown to kill two close relatives of COVID-19: SARS-CoV-1 and MERS-CoV.

Source: link

What dose do we need to kill?

A dose of .2 J/cm^2 reduced the infectivity of SARS-CoV, CCHFV, and NiV. Source: link

It is predicted that a UV dose in the range of 25-31 J/m^2 will be lethal to the family of RNA known as Coronaviridae. Coronavirus is the common name for Coronaviridae.

Source: link

Dosage is dependent on the time exposed. If the groceries are in the chamber for 10 seconds, the dosage will be 5813 J/m^2. This far exceeds the predicted dosage that will kill COVID-19.

Sources: “Large-scale preparation of UV-inactivated SARS coronavirus virions for vaccine antigen,” Tsunetsugu-Yokota Y et al. Methods Mol Biol. 2008;454:119-26. doi: 10.1007/978-1-59745-181-9_11

“Efficacy of an Automated Multiple Emitter Whole-Room Ultraviolet-C Disinfection System Against Coronaviruses MHV and MERS-CoV,” Bedell K et al.ICHE 2016 May;37(5):598-9. doi:10.1017/ice.2015.348. Epub 2016 Jan 28

“Focus on Surface Disinfection When Fighting COVID-19”; William A. Rutala, PhD, MPH, CIC, David J. Weber, MD, MPH; Infection Control Today, March 20, 2020 (https://www.infectioncontroltoday.com/covid-19/focus-surface-disinfection-when-fighting-covid-19)

“Preventing the Spread of Coronavirus Disease 2019 in Homes and Residential Communities”; National Center for Immunization and Respiratory Diseases (NCIRD), Div. of Viral Diseases (https://www.cdc.gov/coronavirus/2019-ncov/hcp/guidance-prevent-spread.html)

“New coronavirus stable for hours on surfaces”; CDC (extracted from N van Doremalen, et al. Aerosol and surface stability of HCoV-19 (SARS-CoV-2) compared to SARS-CoV-1.The New England Journal of Medicine. DOI: 10.1056/NEJMc2004973 (2020)) (https://www.nih.gov/news-events/news-releases/new-coronavirus-stable-hours-surfaces).

Safety:

From the product specs, glass filters out ozone, so no ozone is emitted.

Acrylic covering will prevent light from getting out, so the cashier will not be exposed to harmful UV rays. Source: link

Electronics

Schematic: The device will be powered by a common American wall socket. This will pass through a single pole single throw 15 amp switch. Then, using a full wave rectifier, the bulbs will be provided with the steady required voltage.

Operating voltage for the bulb is 105 V and .44 A. I used LT Spice to simulate the circuit and get these required conditions.

Parts needed/Cost:

Full wave rectifier resistor, capacitor Fuse Acrylic Panels Flaps Bulbs UV resistant glue

Estimated Cost: 12 + 45 + 15 + 15 + 33 = 120 dollars / Unit

Longevity:

After 18000 hours, the UVC output of the bulb remained at 85%. http://www.mcp-hybec.co.jp/en/products/img/lamp/TUV%20Technical%20Data.pdf

Challenges we ran into

We wanted to make sure the UV light was actually doing something, but we didn't want to harm the cashier or customers with radiation. We needed a material that blocked UV rays, was relatively cheap, and could stand over a check out conveyor belt.

For the bulb, we had to learn how UV disinfection works and how to make it effective. By reading research papers done on the effectiveness of different doses of UV-C light, we were able to find out what we needed to make the product effective.

There has not been a comprehensive study done on if COVID-19 itself will be killed by UV light. But, there has been a lot of research into close relatives of COVID-19 and the family of RNA that is in COVID-19, Coronavirus. UV-C light in the right dosage will kill these close relatives, and it has been predicted that the whole family of RNA known as Coronavirus will die in doses from 25-32 J/m^2. Knowing that this was under a controlled environment, we surpassed it by quite a large margin.

Accomplishments that we're proud of

We modeled the product in a 3d render, and we simulated the circuit required for the device. We managed to make it pretty affordable as well.

What we learned

We learned about the problem of single use plastics and how the environment is being affected by plastics. We learned about the global impacts of COVID-19, both socially and economically. We learned how UV lights are categorized, how they kill viruses, when they can be effective and when they aren't, and how to be safe around them.

What's next for Scanitizer

It is affordable when considering the costs that grocery stores face when it comes to the checkout. Our next goal would be widescale implementation to lower the risks of food-borne illnessess and replace the need for extraneous single use plastic packaging. We also aim to replace chemical cleaning products which may have a harmful effect on the environment. Aside from reducing infections, we aimed to restore consumer confidence in shopping. We hope people will be reassured by our product and choose to purchase more produce and non-packaged items. Post COVID-19, we hope our project will help to restore life back to normal by giving people a feeling of safety when going grocery shopping.

Built With

  • creo
  • spice
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