README.md

Wood Pulp Filter for Covid - 19

This project is been developed by Paloma Gonzalez and José Tomás Domínguez in a collaboration of Arauco and UTFSM Fablab.

COVID-19 has generated a global demand for face masks that our supply chains haven't been able to satisfy. Therefore, there is a huge need to create new materials and manufacturing methods to fabricate face masks and filters. We are working on a wood pulp filter that protects from Covid - 19, and could potentially be produced anywhere where there is a wood pulp factory. Wood pulp factories are present in most regions of the world.

Our goal is to physically modify wood pulp sheets to achieve the filtering performance of a N95 filter to produce a functional layer for respirators / masks / PPE for the corona viruses. Wood pulp is the raw material for paper towels with the capacity of filtering particles of 0.3 μm. The corona virus measures approximately 0.1 μm. We can modify the compaction of the layers and/ or the size of the fibers to increase their filtering capacity / breathability.

Filter + Half Face Mask

According to our calculations the half mask will cost $0,029 and the filter will cost $0,1. We are also developing a face mask which filters can be exchanged, completely out of molded wood pulp, taking advantage of our raw material. Our design is based on Wasp’s design but we are looking to work with injection molding and/or 2 mold processes instead of 3D printing. It is crucial to be able to mass produce the half masks. The advantage of Wasp design is that the filters are held on the inside side of the mask, decreasing the contamination of the filters when changing them. There are also fabric masks in which these filters could work like this one, the HKMask.

Molded wood pulp is meant to be a disposable material and it is 100% biodegradable as all the additives we are suing are. This is a characteristic that we want to take advantage of as after the pandemic we wouldn't want to have polluted the environment with more waste. This also means that the half masks will last less than N95 or other masks. We embrace such short temporality, and will asses it to notice our users. We expect that these protective equipment lasts 3 to 4 weeks.

Filter Key Parameters to measure [2]

• Scanning Electron Microscope SEM: This tests characterize the materials porosity. Target: < 0.1 um. - Update: Camron did SEM imaging: SEM
• 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].