Fighting Germs

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Hopefully this blog will help spark good ideas to combat the Covid-19 virus and other nasty bugs. This year I have not been blogging every week and just focussing on doing projects instead, but the call for ideas to help alleviate this crisis is a good reason to try and contribute solutions. I suppose it might be possible to make money off some of these ideas, but I would rather mobilize everyone to create solutions. Rather than wait for the ideas to be developed into working devices, I wanted to get them into everyone's hands immediately. This means they will still need further work and research to become practical solutions.

This bog starts off with a few ideas and gets into a build later in the blog.

The first set of ideas is around preventing transmission by physical contact with communal surfaces.

It should be possible to retrofit many commonly contacted surfaces with hands-free mechanisms:

  • door handles - become automatic doors - using facial recognition, voice recognition, ultrasonics, radars
  • cupboard handles, refrigerator door handles, toilet flush handles can all be hands-free automated
  • phones - voice control answering of a phone which goes to speakerphone
  • light switches - hands-free voice control or gesture control
  • microwave and stove controls - voice control of settings and door opener
  • faucet taps - hands-free voice control, IR control, gesture control
  • washing machines, dryers, dish washers - voice control of settings and door opener
  • etc

The next set of ideas deals with airborne transmission at work.

Some businesses must still operate, albeit with skeleton crews, but while at work some extra distancing precautions can be taken:

  • Put arrows on the floor so everyone walks in the same direction with suitable separation and no passing in the hallway.
  • Create a scheduling app to book and use the restrooms, cafeteria and any other facilities without overlap.
  • If your employees have android 9 phones, create an app to show where everyone is in the building.


The last set of ideas deals with attacking airborne virus.


The first idea make a device that kills the virus before you can breathe it in is Germ Zapper. This device is basically just 2 bare wires wound on a frame, very close together, but not touching - conceptually like this:

The idea is to apply a voltage between the wires that is very close to the breakdown voltage of air, so when air is blown though the wires any particle will cause the gap to reduce enough to cause a breakdown. The resulting spark needs to have enough energy to fry or zap the particle. In this picture the capacitor would store enough energy to zap a virus particle. Since the spark would ionize air and create a conductive plasma, when the capacitor discharges, there would not be enough current to maintain the current flow, which would quench the spark and air would blow it away. So this system just needs a fan to blow infected air through the wires and hopefully with enough layers of wires, all virus particles would be killed on the way through.

Virus particles are approximately 0.1 micron in diameter which is really small compared to wire diameters, but this technique is very similar to the apparatus used to detect subatomic particles, which are much smaller. The breakdown voltage of air is about 30K volts per mm, so if the spacing between wires is much less than 1 mm, the system could use  less voltage. The breakdown voltage will vary with humidity, but a feedback control circuit can be used to determine the exact local breakdown voltage.


The second idea is to kill the virus with heat - the Germ Fryer. This system simply heats up the air long enough to kill any virus present and then cools it back down to breathable temperatures:

The system needs a fan, heater and a cooler. Several cooling technologies also have heat as a byproduct, such as Peltier effect coolers and refrigerators, so some efficiency could be realized by using such technologies. It will require some research to determine what temperatures are needed to kill Covid-19 and how long they need to last, but conceptually the technique should work.

Some people are suggesting ultraviolet light would be a good way to kill the virus. I'm not keen on this as it would take a lot of UV and UV is dangerous in its own right, and I'm worried that UV can cause mutation (as it does with melanoma), and I wouldn't want to take a chance of mutating Covid-19.


The third idea is to make a Germ Pulverizer. Virus particles are tiny little flimsy particles that are probably easy to crush, smash or pulverize. The concept is to blow air through some rotating mesh disks or tubes where any particles cannot get through without being hammered by a wire in the mesh.

The fan and mesh disks could have separate motors or be linked with a gear train, and there could be several disks ganged and interleaved to create a tougher gauntlet. The mesh disks would spin at high velocity to ensure destruction of virus particles. There are many ways to devise a system that will beat up the air, and anything in it, as it passes through. It is just a matter of calculating the probability of virus sized particles hitting a wire or blade, based on relative velocities.


The fouth idea is a way to filter air with a centrifuge type of concept. I'm calling it a CentrAirFuge.

The idea is to blow air through a rotating tube, such that all particles will be accelerated to the walls. Clean air can then be collected from the center of the tube. I built a 3D printed version of such a machine to demonstrate the principle. The main component is a tube with vanes in it to ensure all air is rotating and a fan blade at the inlet to ensure air moves through the tube. I call this tube the impeller. There is an exterior tube to hold the impeller motor and the exhaust plenum.

The tube needs to be rotating fast enough and the tube needs to be long enough that all particles have time to reach the outer wall. The walls of the 3D printed tube have a ribbed texture due to the printing method. The ribs are much larger than the virus particles and would probably do a lot of damage to the delicate particles as they tumble along the wall, so not only should the device produce clean air, any virus in the dirty air (which should be all virus particles) is likely very damaged. Research would be needed to determine what speeds work, if the concept works on the virus at all and whether the walls damage virus particles.

Here is a video showing the concept:

I hope these ideas inspire others to make useful items to combat Covid-19.

I had one other idea for a low cost mask - it is described here:

Corona Cap


Stay safe and consider others ....