@@ -24,14 +24,25 @@ The advantage of Wasp design is that the filters are held on the inside side of
We think that this detail would help decrease the contamination of the filters when changing them.
There are also fabric masks in which these filters could work [like this one, the HKMask](https://diymask.site/).
Key Steps:
SEM Measurements, measure the porosity of the wood pulp sheets; it must be >0.1um
Particle counting measurement, measure filtering capacity of the material, the ideal scenario will be an N95 filtering capacity.
In case the material's porosity is bigger than 0.1um or the filtering capacity isn’t enough, Arauco is going to modify their manufacturing process to get a tighter material, or we are going to test a Electrospinning machine.
Make the material Hydrophobic.
## Key Parameters to measure [[2](https://scientificfilters.com/wp-content/uploads/2016/03/BasicFiltrationConcepts.pdf)]
- Selective Electron Microscope [SEM](https://en.wikipedia.org/wiki/Scanning_electron_microscope): This tests characterize the materials porosity. Target: < 0.1 um.
- Particle Retention Rate: "In a filtration process, the particle retention efficiency of a depth-type filter is expressed in terms of the particle size (in µm) at which a retention
level of 98% of the total number of particles initially challenging the filter is
obtained". Target: 95%
- Preassure Drop: The higher the pressure drop, the harder it is to breathe. Target: <5.82 [mmH20] at a flow rate of 32 [L/min].
Filter Development
All this tests could be replaced by a DOP ([DOP Guideline](http://www.eacoontario.com/pdf/2013/Revised%20August%2027%202013%20DOP%20PAO%20HEPA%20IntegrityTesting%20Procedure.pdf)).
## Key Steps:
- SEM Measurements, measure the porosity of the wood pulp sheets; it must be >0.1um
- Particle counting measurement, measure filtering capacity of the material, the ideal scenario will be an N95 filtering capacity.
- In case the material's porosity is bigger than 0.1um or the filtering capacity isn’t enough, Arauco is going to modify their manufacturing process to get a tighter material, or we are going to test a Electrospinning machine.
- Make the material Hydrophobic.
-Industrial production.
## Filter Development
Wood pulp sheets have the following disadvantages:
Hydrophilic, absorbs any liquid very fast so it could have a lower life expectancy and could absorb contaminated droplets, this can be controlled through design or modifying the material properties.
Due to air flow, the user could inhale wood pulp fibers, we are adding wood pulp based fabrics to act as a filter. It’s relevant to point out that wood fibers aren’t toxic, you just can’t digest them.
