- Covid and similar threats will be here for a while. We need ubiquitous protection.
- Ultraviolet-C is one of the tools; it comes with a lot of promises and a lot of challenges.
- The most likely candidate for a ubiquitous UVC source is the UVC LED.
(1) Design an emitter cell based on UVC LEDs, that is:
- Optimized for COVID efficiency, well characterized and documented;
- Scalable: should be usable as the core of a multitude of UVC-based disinfection devices;
- Manufacturable by guerrilla methods: decentralized, by non-professional teams, with general purpose equipment and widely available materials.
(2) Release the design to the public domain, under a fully commercial, royalty-free, public license, so that anyone wishing to build or expand the design can do it immediately and free.
What it does
It provides a reference design of an UVC emitter that can be easily manufactured using 3D printing technology and general purpose materials, upon which a variety of other disinfection devices can be built upon.
A small disinfecting cover based on the emitter was designed and built as a demonstrator. It can disinfect small objects like a credit card or a key and it can be scaled to any size to disinfect any flat or slightly curved surface, from phone to laptop to desk to bed.
How we built it
First we built a CNC-based UVC measurement setup to allow us to characterize the irradiance pattern arround our emitter. We hijacked a milling CNC from our workshop and connected it to a ARM Coretex-M4 development board, then 3D printed a custom mount to attach the sensor to the mechanical rig. We wrote the firmware that controls the entire system and communicates to a computer through USB, and also the computer software that takes the measurements, which we processed in Matlab.
We designed a 3D printable UVC emitter around commercially available LED strips, and devised a way and tool to make it reflective. We then characterized the irradiation pattern around this emitter, to allow anyone using it in a UVC disinfection device to calibrate the system parameters such that the desired dosage can be achieved and the exposure time minimized.
As proof of concept, we then designed and made a small, flexible, UVC disinfection cover 3D printed on polyproplylene (PP), which is food safe and semi-flexible. It uses 25 2mW UVC LEDs mounted on a flexible strip and 25 emitters of our own make. It can provide a dosage of minimum 40 mJ/cm2 over the entire exposed area in 3.7 minutes.
- Refine the project – the optical design is most likely suboptimal, we hoped to find a professional in the field at this hackathon but it didn’t happen.
- Build another demonstrator with the updated design and test its effectiveness against COVID-19. For this we’ll need to find a microbiology research lab to partner with.
- Publish and maintain all the technical data on crowdinvent.com