Title of the Invention: NOVEL AND IMPROVED BIODEGRADABLE FACE MASK WITH INHERENT VIRUCIDE, HYDROPHOBIC AND HYDROPHILLIC PROPERTIES WITH ADJUSTABLE EAR LOOPS.

Technical Field: Eco-friendly, bio-degradable face mask made of nanotechnologically engineered cotton fabric materials chemically modified to possess super hydrophobicity to the outer layer, mechanical and electrostatic filtration to with virus and bacteria destroying activity to the middle layer and hydrophilic inner layer capable of absorbing carbon dioxide and moisture in the exhaled air and fast evaporation, materials used and the method for preparing the same.

Field of the Invention: Health care application in personal protection face mask for both self- and population-protection.

Background Art:

With an unexpected emergence of the COVID- 19 disease into the day-to-day life of the human population, the entire world has come to a state of standstill thus hampering economic, social, educational and all other activities. A highly infectious virus, a lengthy incubation period and the presence of a high percentage of asymptomatic carriers have contributed to abrupt and widespread propagation of the disease ultimately resulting in the current pandemic. It is well accepted that the COVID- 19 spread is best limited by improved personal hygienic practice and social distancing. As such, wearing of proper face mask has become vital for the entire world population. A facial mask not only limits infection risk to the wearer but also, more importantly, it protects the immediate population from acquiring the disease via a symptomatic patient or an asymptomatic carrier who wears a mask. The importance of advocating for everyone to wear a mask has the added advantage that it prevents people getting infected after touching their faces with possibly contaminated hands as well as them transferring infectious secretions to fomites. Since the COVID-19 is apparently highly infectious and virulent, any and every means of reducing the infectious dose should be utilized, Considering both these factors the development of a simple, low-cost, reusable, yet properly functional mask should be of highest priority.

Currently available face masks can be generalized to three categories. The cloth masks used by the general public limits the large droplet spread mainly from the wearer. It has minimal/no nanoparticle or viral filtration. The surgical mask, used by healthcare workers, has variable filtration efficacies in terms of stopping viral spread. Depending on the manufacturer and quality of surgical masks, the filtration efficacy varies in the range from 5% to 40% at the desired 300 nm particle range. The mask doesn’t tightly fit the face which results in air leakage from unfastened sides. The standard N-95 respirators are custom fitted to the face and are used by healthcare groups at high exposure risk from infectious aerosols. The mask should have at least 95% filtration at the 300 nm level. The much-vaunted N-95 respirator has its inherent drawbacks severely crippling its use in the pandemic setting, namely, advocating for single usage and being highly labile for commonly available disinfecting mechanisms.

Patent No. CZ 16988 U1 deals with a face mask that is capable of removing physical and / or biological impurities from the exhaled air, which comprises an outer textile layer and an inner textile layer between which at least one nanofibrous layer consisting of at least partially nanofibres containing particles of at least one active substance. The present invention is different to this because it’s all three layers are made of using nanotechnologically engineered fabric to have required properties to the different layers. Further, the present invention uses environmentally friendly biodegradable cotton in contrast to the non-woven material used in the above patent. In the present invention, the upper layer is superhydrophobic to repel aerosol particles, blood and stain. The middle layer has both mechanical and electrostatic filtration and virus and bacteria deactivation. The inner layer is made of hydrophilic cotton to absorb moisture and carbon dioxide in the exhaled air and to evaporate out quickly to prevent accumulation of carbon dioxide rich atmosphere in the headspace between the mask and the face. Further, the present invention uses the positively charged surfaces to attract the negatively charged viral envelope and bin electrostatically on their surfaces. Whereas, the above patent is antistatic. The present invention prevents the wearer from getting the virus and giving the virus to the environment. Therefore, it works in both ways.

Patent No. EP 2654476 A2 deals with an apparel or material that may be placed anywhere or worn about the neck or other parts of the body of a human. The apparel material has a structure that, when repositioned from about the wearer, will retain a position about a mouth and nose of the human, as by elasticity or toughness of a wrapping about the face. The apparel is sufficiently porous as to allow a human to breath comfortably through the fabric when placed over the mouth and nose of the human. The fabric has as a coating is created with on at least the outer surface and through at least 25% of the thickness of the fabric a moisture- sensitive antimicrobial composition, wherein the antimicrobial moisture-sensitive composition comprises an antimicrobially active compound and a carrier, the carrier by hydrophilic and able to absorb sufficient moisture from exhaled breath from the human as to maintain a wet surface on the carrier to which viral particles will adhere more strongly than to a dry surface of the same carrier. This invention is very different from the present invention since the latter has three layers made of nanotechnologically engineered cotton fabric to have different properties to the three layers.

Patent No. JP 5740653 B2 is based on a composition for coating a polypropylene-based fabric or polypropylene-based material for use in decreasing the transmission of human pathogens. A device such as a protective face mask made from a polypropylene-based fabric or polypropylene-based material coated with the composition. The present invention does not deal with polypropylene materials but environmentally friendly, bio-degradable cotton fabric-based face mask.

Patent No. JP 2013-67618 A provides an antiviral agent for application to fibers used in protective clothing, masks and the like. A compound of general formula M _n X _y (wherein M is an element such as calcium, aluminum, zinc, nickel, tungsten, copper, silicon, etc .; n is an integer of 1 to 3, and X is oxygen, phosphoric acid) ion, hydrogen phosphate ion, dihydrogen phosphate ion, carbonate ion, sulfate ion, nitrate ion, etc., and y represents an integer of 0-4)). Fiber coated with nanoparticles used as an article or filter to reduce and / or prevent viral transmission. This invention deals only with nanofiltration and to prevent or reduce viral transmission. The invention does not deal with three-ply masks with different properties introduced to different layers.

The article “Antiviral Potential of Nanoparticles — Can Nanoparticles Fight Against Coronaviruses?” by Gurunathan, Sangiliyandi Qasim, Muhammad Choi, Youngsok Do, Jeong Tae Park, Chankyu Hong, Kwonho Kim, Jin-Hoi Song, Hyuk, published in August 2020 explains that preventing COVID-19 in the host can be more effective than fighting against the virus after infection It describes the possibility for using unconventional antiviral agents such as nanoparticles as antiviral agents for preparing masks, clothes, gloves and gums and for the treatment of various viral infections and the benefits. It does not deal with face mask materials, methods and the product.

A review article “Science-Based Strategies of Antiviral Coatings with Viricidal Properties for the COVID-19 Like Pandemics” by Pemmada, Rakesh Zhu, Xiaoxian Dash, Madhusmita Zhou, Yubin Ramakrishna, Seeram Peng, Xinsheng Thomas, Vinoy Jain, Sanjeev Nanda, Himansu Sekhar, Materials, published in September 2020 addresses the possibility for using unconventional antiviral agents such as nanoparticles as antiviral agents for the treatment of various viral infections and the benefits. There it reported the impregnation/coating of classical antibacterial metals/metal oxides in nano/micro size scales, such as copper oxide, zinc oxides, titanium oxide, silver oxide etc. onto disposable N95 respiratory mask layers, which showed that the mask layers had an anti-viral activity against human influenza A virus (H1N1) and avian influenza virus (H9N2). However, the N95 mask does not have the hydrophobic and hydrophilic layers presented in this invention. At the same time the present invention is biodegradable as opposed to the N95 masks.

In a review article Biomaterials-based formulations and surfaces to combat viral infectious diseases by Kumari, Sushma, Chatterjee, Kaushik published in February 2021, they describe the possibility for using unconventional antiviral agents such as nanoparticles as antiviral agents for the treatment of various viral infections and the benefits. They have also stated the importance of exploring fully compostable and biodegradable antiviral facemask. The present invention however, deals with addressing the problem stated in the review article.

In another review article, “Recent Advances on Nanomaterials to COVID-19 Management: A Systematic Review on Antiviral/Virucidal Agents and Mechanisms of SARS-CoV-2 Inhibition/Inactivation” by Carvalho, Anna Paula A. Conte-Junior, Carlos A., in February 2021, it describes the interface between nanomaterials and the main mechanisms to inhibit SARS CoV 2 pathogenesis and viral inactivation. Nanocarbons, biopolymeric, copper, and silver nanoparticles are potential antiviral and virucidal agents toward self- cleaning and reusable filter media and surfaces (e g., facial masks), drug administration, vaccines, and immunodiagnostic assays. It also deals with phytochemicals delivery by nanocarriers also stand out as candidates to target and bio-friendly therapy and states that nanocellulose might fill in the gaps. The present invention is aimed to fill the gaps identified in the review article.

The substandard virus-containing particle filtration efficiency of the surgical masks puts the health care worker as well as the COVID-19 uninfected patient at a great risk. The availability of even the surgical masks-essentially for single use-are still limited in most countries. Persistence of COVID-19 virus, even at 7 days, within the N-95 respirator, poses a grave threat to the health care worker (HCW) in contact with large number of suspected and confirmed patients. An additional risk lies to the patients, some of whom may get nosocomial infection unintentionally by the attending HCW-a scenario suspected in Italy. The same HCW may also cause infection of co-workers at the same institution with the real possibility of shut down of critical hospital department at a crucial time.

The often-forgotten cohort of armed forces and police personnel, called-in to control the emergency situations inevitably arising in the pandemic setting, highlights a previously unaddressed requirement where the individual is at risk due to contact of a large number of people-some of whom might be infected. The affected person can then cause infection of a large number of uninfected individuals, both in the community being handled and in the same cohort. Another exposure category would be school teachers, shop vendor and cashiers, bus conductors, and so forth. These groups have a high risk of spreading the disease if contracted. School students present another unique situation as keeping the social distance would be a challenge particularly in a congested school environment. Another difficulty would be keeping the face mask on the right position for a long period of six continuous hours at school and during transit. Custom-designed masks with ease-of-use fastener would be required to address these issues. The general public, currently clad in ineffective makeshift cloth masks, may be at high-risk for unintentional disease spread. However, the cost is another important factor that needs to be addressed properly when it comes to low-income categories particularly in this shut down situation.

Considering these unique populations with wide and different requirements, the currently available three types of masks; namely, cloth masks, surgical masks and N-95 masks, are not very feasible. As such, custom-designed masks based on a common platform based upon variable filtration efficiencies for nanoparticles with inherent virucidal activity would be ideal particularly if made reusable.

To design appropriate masks for cohorts of differing needs, a novel strategy is required for designing, developing and manufacturing custom-made face masks from commonly available fabrics via chemical modifications to suit the specific requirements. This innovation addresses the unique and well-timed concept of inherent viral deactivation via multiply mechanisms within the mask material. This coupled with re usability and stability to common methods of disinfection makes the mask design more functional and versatile than the currently available best standard mask in the long run.

The inventions described here, address the given limitations by suitably modifying woven cotton fabric of GSM 188 (Grey cloth) with suitable materials to reduce pore size of the fabric below 300 nm. This is achieved by entrapping and chemically bonding different types of nano- to micro-particles within these pores. The types of nano- to micro-particles used are titanium dioxide, zinc oxide, calcium carbonate and magnesium oxide, all of which are non-toxic, bio-compatible, non-hazardous and environmentally-friendly. Chemical attachment of the nanoparticles within the pores of the fabric mesh is achieved through suitable binders such as poly acrylic binder or polyurethane binder that is generally used in the textile industry. Since the particles are chemically attached to the fabric fibers, there is no risk of inhalation of these particles. When zinc oxide or titanium dioxide nanoparticles are used, there is an antimicrobial effect enabling to destruction of the virus. Zinc oxide has its antimicrobial effects even in the dark, due to surface zinc ions and through photo-catalytic activity below 380 nm wavelengths. Titanium dioxide has its antimicrobial activity due to inherent photo-catalytic activity below 380 nm wavelengths and the activity can be shifted to visible region by suitably modifying titanium dioxide with N-doping, S-doping and so on. Titanium dioxide nanoparticles prepared at slightly lower pH (between 5 to 6) have surface positive charge-due to adsorbed photons on the surface hydroxyl groups-enabling electrostatic attraction of viral particles (whose surfaces are negatively charged) and destructive capability due to antiviral effect of the metal particles used to modify cotton fabric. Antiviral activity can be further enhanced by attaching copper nanoparticles which act via the so-called “contact killing effect”, where surface copper ions destroy the outer coating of the viral particles. The known virucidal effects of the metal compounds would be accentuated hundred-fold by the increased surface area achieved by using nanometric size particles.

Technical Problem: To address the problem of the dearth of high-quality face masks currently prevailing in the global context with essential properties namely; hydrophilicity, hydrophobicity, virucide, biodegradability and customizability depending on requirements of different categories of populations, breathability all the while featuring an affordable price.

Technical Solutions: The technical problem was solved by developing custom-designed face masks which was achieved by the development of three-ply masks with superhydrophobic cotton fabric based upper layer, antimicrobial middle layer, hydrophilic innermost layer and adjustable ear loop which can be adjusted to perfectly fit the face of the wearer. The fabrics and chemicals used for the development of the mask are nontoxic in nature and biodegradable while also being able to reuse by washing making it cost effective.

Brief description of drawings:

• Figure 1 Shows (a) Optical images of a water droplet on fabric surface modified by TiO ₂ /stearic acid, ZnO/stearic acid and SiO ₂ / hexadecyltrimethylsilane combinations.b) The image obtained in the contact angle measurement fabric surface modified by TiO ₂ /stearic acid, ZnO/stearic acid and SiO ₂ / hexadecyltrimethylsilane combinations.

• Figure 2: Optical micrographs of the (a) untreated, (b) partially-treated and (c) higher dose of treatment and (d) fully-treated cotton fabric.

• Figure 3: enhanced 3 -Ply cloth mask with Three layers a) Outer layer, b) middle layer and c) inner layer

• Figure 4: Virucidal mask with multimodal enhanced filtration. Advantageous effects:

• All the layers are made from environmentally friendly, Bio-degradable Cotton. And the chemicals are non-toxic and bio-safe

• The face mask is washable, ironed and reused. They are reusable at least up to 20 washing cycles

• The outer layer cotton has been nanotechnologically engineered to have superhydrophobic properties as the way lotus leaf surface has.

• The outer layer therefore repels any aerosol particle containing the virus, any water droplets, blood droplets and stain and remains fresh for several days.

• The middle layer cotton fabric has been nanotechnologically modified by chemically attaching microparticles to cover the pores down to 300 nm.

• It prevents mechanical filtration of the particles down to the size of 300 nm.

• Since the microparticle surfaces are positively charged these surfaces attract the negatively charged viral envelope and bin electrostatically on their surfaces.

• In that way, the middle layer prevents the penetration of the virus by electrostatic filtration also.

• The middle layer surface also has chemically bound star-shaped nanoparticles.

• These nanoparticles can destroy the virus and bacteria.

• The inner layer is made of hydrophilic cotton to make sure quick absorption of moisture and carbon dioxide in the exhaled air and evaporate out of the headspace between the mask and the face.

• This prevents the possibility for re-inhalation of carbon dioxide-rich air and gives comfort to the wearer.

• The materials used are chemically bound to respective fabrics so as not to detach and inhale by the user.

• The unique shape and adjustable ear straps make sure the tight fitting to the face

• Chemically stable to treatment by 70% isopropyl alcohol and 8%H ₂ O ₂

• No alteration of filtration capacity after washing cycles with detergents

• Stable to wet and dry forms of heat for steaming and oven drying at 120 °C for few minutes

• Stable to microwave treatment

• No degradation due to UV light, sunlight, X-ray and gamma ray treatment • Uniquely adaptable for various cohorts of different needs, spanning a wide spectrum including highly specialized laboratory settings across to the school children and the general public

Mode for invention:

Materials Developed

Commonly available, low-cost material is modified in this economically-restricted pandemic setting, Enhancement of the virucidal, filtration and hydrophobic activities across multiple layers are achieved with unique configurations to suit different cohorts within the population. The outer mask layer is made super-hydrophobic, moldability layer where a face fit is required High grade filter layer where nanoparticles bound by chemical adhesion to the material pores increase the filtration efficiency by reducing the pore sizes as well as improving the electrostatic attachment. The nanoparticles cause multimodal virucidal effects via photocatalytic activities and Contact Killing, A soft inner layer with moisture absorption leaving the filter area in contact with mouth and nose free of fluid clogging, An added layer of activated charcoal filtering chemical vapor and odor control, to be used in removable filters of gas mask type PPE, as well as for exhaust filtration in mechanical ventilators and air conditioners Cleanable rigid filter layer of Copper/ Bronze which has backup virucidal effects is planned for equipment with exhaust. This involves five tasks as described below.

The outer layer of three-ply masks should be made from a hydrophobic/superhydrophobic fabric to enable it to be able to repel any charged particles such as viruses and moisture. The hydrophobic/superhydrophobic property ensures stain-resistance and hence increased durability of the mask with its fresh and clean appearance for several days. It also prevents moisture seeping through the top layer to reach the middle layer. However, since the pore structure of the fabric is reserved the respiration is not objected by this layer. This can be achieved in many ways.

1. Using self-assembled stearic acid molecules on vertically-aligned titanium dioxide or zinc oxide nanotechnological architectures with hierarchical structures such as nanorods, nanoflakes and nanoflowers on the fabric surface.

2. Using hexadecyltrimethoxysilane self-assembled on silica nanoparticles.

3. Using C-6 or less fluorocarbons.

All these methods have already been developed in our research group to introduce superhydrophobic/hydrophobic properties to various fabric surfaces. In the current context, these methods are used to make the Cambrella fabric superhydrophobic. Figure 1 shows the contact angles of a water droplet on cotton, modal and viscose fabrics. Figure 1 (a) shows optical images of a water droplet on fabric surface and 1 (b) shows the image obtained in the contact angle measurement. The measured contact angle values for the different systems are depicted in Table (1). This task involves modification of woven cotton fabric of GSM 188 (Grey cloth) with suitable materials to reduce pore size of the fabric below 300 nm. This is achieved by entrapping and chemically bonding different types of nano- to micro-particles within these pores. The nano- to micro-particles used in this invention are derived from commonly available naturally occurring minerals. The types of nano- to micro-particles used are titanium dioxide, zinc oxide, calcium carbonate and magnesium oxide, all of which are non-toxic, bio-compatible, non-hazardous and environmentally-friendly. Chemical attachment of the nanoparticles within the pores of the fabric mesh is achieved through suitable binders such as polyacrylic binder or polyurethane binder that is generally used in the textile industry. Since the particles are chemically attached to the fabric fibres, there is no risk of inhalation of these particles. When zinc oxide or titanium dioxide nanoparticles are used, there is an antimicrobial effect enabling the destruction of the virus. Zinc oxide has its antimicrobial effects even in the dark, due to surface zinc ions and through photocatalytic activity below 380 nm wavelengths present in sunlight or radiation emanating from operation theatre lamps. Titanium dioxide has its antimicrobial activity due to inherent photocatalytic activity below 380 nm wavelengths and the activity can be shifted to visible region by suitably modifying titanium dioxide with N-doping, S-doping and so on. Titanium dioxide nanoparticles prepared at slightly lower pH (between 5 to 6) have surface positive charge-due to adsorbed photons on the surface hydroxyl groups-enabling electrostatic attraction of viral particles (whose surfaces are negatively charged) and destructive capability due to antiviral effect of the same nanoparticles as well as metal particles used to modify cotton fabric. Antiviral activity can be further enhanced by attaching copper nanoparticles which act via the so-called contact killing effect, where surface copper ions destroy the outer coating of the viral particles. The known virucidal effects of the metal compounds would be accentuated hundred-fold by the increased surface area achieved by using nanometric size particles. The task can be achieved as follows.

Method of entrapping TiO ₂ nano- to micro-particles within pores of cotton fabric

TiO ₂ nano- to micro- particles were prepared using required amounts of titanium isopropoxide (one or more values in the range from 1 to 500 mL), acetic acid ( one or more values in the range from 1 to 100 mL) and ethanol or isopropyl alcohol (one or more values in the range from 1 to 5 L) as raw materials and mixing them into clear solution, passing steam through it to form milky suspension and autoclaving the mixture at a temperature in the range from 50 °C to 250 °C for a period of time in range from 1 to 10 hours. The dipping process was achieved by first preparing the dipping solution as detailed below. A required amount of the above colloidal solution (one or more values in the range from 1 to 200 mL) was added to absolute ethanol or 100% isopropanol (one or more values in the range from 1 mL to 1 L) and thoroughly mixed. Previously autoclaved fabric (10 cm x 10 cm for laboratory studies and large pieces such as rolls was dipped in the solution while stirring and heating to boiling. Required amount of ethanol (strength in the range of 1% to 50% and volume in the range of 1 to 500 mL) was then added slowly while stirring and allowing the solution to boil until colloidal nanoparticle formation is completed. The fabric is then removed from the solution and dried in air followed by oven drying at 100 °C to 150 °C for a few minutes. In the spray method, the above solution was sprayed onto previously autoclaved fabrics to varying lengths depending on extent of pore-filling required. Figure 2 shows optical micrographs of the (a) untreated, (b) partially-treated and (c) higher dose of treatment and (d) fully-treated cotton fabric.

Particle filtration study was carried out at the Sri Lanka Institute of Nanotechnology (SLINTEC) and the report for samples (c) and (d) is given in Appendix I. Data show that for the Specimen 1: 3M ^® N95 Mask, the percentage reduction vales of particles at 0.3, 0.5, 1, 2, 3 and 5 micron ranges are 80, 84, 89, 90, 88, 93 indicating that what should be 95% at 0.3 micron is indicated as 80%. On the same basis the 100% filtration efficiency at 2, 3 and 5 micron sizes lie within 88 to 93. For the Specimen 2: Standard surgical mask the corresponding values are 37, 563, 74, 79, 86 and 94%, respectively. The best efficiency of a surgical mask is around 40% and a very close 37% is obtained for this particular surgical mask though the value depends on the manufacturer and the quality. For some surgical masks the filtration at 0.3 micron obtained was around 10%. For the Specimen 3: Sample A that is the mask material show in Figure 2 (c), has the corresponding values 65, 75, 87, 89, 89 and 95%, respectively and the Specimen 4: Sample B that is the mask material shown in Figure 2 (d), has the corresponding values 67, 77, 86, 89, 90 and 91%, respectively. This shows that even with SLINTEC measurement technique that seems to give slightly lower results have excellent filtration efficiency at and above 1 micron while very good filtration efficiency at 0.5 and 1 micron size ranges. Extrapolation would give rise 80-85% filtration at 0.3 micron level for Samples A and B. Further incorporation of particles enables the 90-100% filtration at 0.3 micron level. Test results are given in Appendix I.

Development of the face-contact layer

The layer that is in immediate contact with the face is meant to give comfort to the wearer as well as to act as a barrier to prevent any pieces of debris that may have generated with wear and tear of the mask. It is quite common that repeated washing procedures applied on textiles and abrasion with various surfaces can make textiles pill to give short chain ends of fabric fibres to come to the surface and stay in a coiled configuration. This fabric filling can be minimized by a suitable chemical treatment. The poplin fabric is used to make this layer of the mask and pilling is controlled by the application of an extra-thin, ~ 50 nm thick layer of a suitable polymeric material on the both sides of the fabric. This is done by spraying the polymeric solution on to the fabric surfaces or by screen printing the solution to the surfaces.

Tests Performed

Guidance for face mask evaluation is provided in the Guidance Document of the Center for Devices and Radiological Health that involves U.S. Department of Health and Human Services, Food and Drug Administration, Center for Devices and Radiological Health, Infection Control Devices Branch, Division of Anesthesiology, General Hospital, Infection Control, and Dental Devices, Office of Device Evaluation. The document is attached in the Appendix II. Accordingly the Surgical Mask and Surgical Respirator “N95 NOISH Certified” are defined as follows.

Surgical Mask: A surgical mask covers the user’s nose and mouth and provides a physical barrier to fluids and particulate materials. The surgical masks referenced in this guidance document include masks that are labeled as a surgical, laser, isolation, dental or medical procedure masks with or without a face shield.

Surgical Respirator “N95 NIOSH Certified”: A surgical respirator is fitted to the user’s face, forming a seal that provides a physical barrier to fluids, particulate materials, and aerosols. If you wish to label your device “N95 NIOSH Certified,” please refer to the (NIOSH) website at http://www.cdc.gov/niosh/npptl/resources/certpgmspt/ (http://www.cdc.gov/niosh/npptl/resources/certpgmspt/) for information about NIOSH's Certification Program Support for Respirator.

For surgical masks, specifications include size, dimensions, tensile strength and other specifications relevant to user needs, e.g., impact resistance. Design features include tie-on or ear loops, elastic or face shield attached. Mask styles include duck bill, flat pleated, cone shaped or pouch. The parameters tested are Fluid Resistance, Particulate Filtration Efficiency, Bacterial Filtration Efficiency, Differential Pressure and Flammability Class.

Fluid Resistance: The fluid resistance is defined as the ability of the mask’s material to resist the penetration of blood and body fluids. It is measured according to the ASTM F 1862: Standard Test Method for Resistance of Surgical Mask to Penetration by Synthetic Blood. According to ASTM F 1862 test method, surgical masks are tested on a pass/fail basis at three velocities corresponding to the range of human blood pressure (80, 120, 160 mm Hg). Fluid resistance may be claimed if the device passes ASTM FI 862 at any levels. Surgical masks that show passing results at higher velocities are more fluid resistant.

Filtration Efficiency: The Particle Filtration Efficiency and Bacterial Filtration Efficiencies are recommended in the said Guideline Document. It is advised to measure these quantities as follows.

Particle filtration challenge is to be conducted using 0.1 -micron Polystyrene Latex Spheres. This in vitro test challenges the mask with un-neutralized 0.1 -micron polystyrene latex spheres and measures penetration. The use of latex spheres provides an appropriately rigorous test for evaluating a sub-micron efficiency performance (ASTM F 1215-89 Standard Test Method for Determining the Initial Efficiency of Flatsheet Filter Medium in an Airflow Using Latex Spheres ). The test that is used in Sri Lanka is the Quantitative evaluation of particulate permeation through face mask materials that is conducted by the Sri Lanka Institute of Nanotechnology. The test method has been described and the results are provided above.

Bacterial Filtration Efficiency (BFE) is defined as a measure of the ability of the mask’s material to prevent the passage of aerosolized bacteria. BFE is expressed in the percentage of a known quantity that does not pass the mask material at a given aerosol flow rate. The test methods used in USA are as follows.

Bacterial Penetration (aerosol filtration)-Mil-M369454C, Military Specifications: Surgical Mask, disposable (June 12, 1975).

Modified Greene and Vesley Method: Method for evaluation of bacterial filtration efficiency of surgical masks. J Bacteriol 83:663-667. (1962).

ASTM F2101-01 Standard Test Method for Evaluating the Bacterial Filtration Efficiency (BFE) of surgical masks using a Biological Aerosol of Staphylococcus aureus.

The bacterial filtration test was conducted at the Bureau VERITAS Sri Lanka for all the fabrics and the test report is attached in the Appendix II. As shown by the data nearly 100% bacterial filtration is achieved with fabric materials.

Differential Pressure (Delta - P) Test: Differential Pressure (Delta-P) is defined as the measured pressure drop across a surgical face mask material. Delta-P determines the resistance of the surgical face mask to air flowing through the mask. Pressure drop also relates to the breathability and comfort of the surgical mask. In general, a lower Delta-P translates to increased breathability.

Flammability Test: One of the following tests can be used to determine flammability class.

CPSC CS-191-53 Flammability Test Method (16 CFR 1610) Standard for Flammability of Clothing Textiles NFPA Standard 702-1980: Standard for Classification of Flammability of Wearing Apparel UL 2154: Test that measures the level of atmospheric oxygen required to propagate flame when ignition is caused by an electrosurgery unit or laser. Higher levels of oxygen required for flame propagation indicate materials which are more flame resistant for electrosurgery or laser procedures.

The fabric materials used pass the Class One Flammability test. Test Report is attached as Appendix III.

Novel Parameters Introduced: These include superhydrophobicity to the top layer, virucidal effect to the filtration layer and reduction of pore size via nanoparticle fixation through chemical attachment. Also the face contact layer was modified to reduce textile pilling and consequent fibre detachment and increased re usability due to virus trapping and disintegration.

Up-scaling of the overall process

This involves design of different types of face masks custom-made utilizing the enhanced outer, middle and inner layers for different requirements of specified end-user populations

The following cross sectional categorization is suggested, in view of current COVID-19 pandemic 1. General Public and School Students

Cloth masks with increased outer layer hydrophobic properties and increased middle layer filtration (up to 50-60% filtration at 300 nm particles) with moderately virucidal nanoparticles.

2. Personnel exposed to large numbers of people with potential for getting infected and spreading the infection; for example, Tri-forces, Police Officers, Shop Workers, School Teachers, Bus Conductors etc.

Cloth masks with increased outer layer hydrophobic capabilities and increased middle layer filtration (80% filtration at 300 nm particles) with moderate virucidal nanoparticles.

3. General Healthcare Workers - Not Exposed to Suspected or Confirmed COVID- 19 Patients

Cloth masks with increased outer layer superhydrophobic capabilities and increased middle layer filtration (80% filtration at 300 nm particles) with enhanced virucidal nanoparticles.

4. Healthcare Workers Exposed to Suspected or Confirmed COVID-19 Patients and Laboratory Workers Handling Infected Materials.

A stiff/moldable fused-layered mask with outer superhydrophobic/hydrophobic and/or oiliophobic/omniphobic nanolayer with further increased filtration (95% filtration at 300 nm particles) with advanced/combined virucidal nanoparticles. This should have a proper seal with the face of the Wearer - to be used after “fit testing”

5. Healthcare Workers/Laboratory Staff Requiring Maximum Protection:

Multilayered material within replaceable filters with superhydrophobic/hydrophobic and/or oiliophobic/omniphobic nanolayer layers, advanced filtration (95% filtration at 300 nm particles) with advanced/combined virucidal nanoparticles such as combined full face mask, powered air purifying respirators.

Conclusion: To achieve pandemic status in a very short period, unprecedented in current times, both in terms of healthcare and economic impact, COVID-19 demonstrate unique adverse properties. Apparent low infectious dose, high virulence of the virus strain, person to person transmission via aerosol and contact resulting in a high R0 value, presence of an asymptomatic carrier status are chief amongst them.

Considering these properties the WHO and other experts agree that the COVID-19 viral spread is best limited by social distancing and improved hygienic practice.

Wearing a mask by almost every individual outside of home (as rightly adopted by Sri Lanka) facilitates the recommended practices by addressing most of the factors of the COVID-19 disease contributing to its impact. The novel and improved face mask materials with inherent virucidal activity not only reduces/nullifies the viral load via inhalation, but reduces the transmission via both the inhalation and contact routes by contributing to good hygienic practice thus reducing the impact of asymptomatic carriers and patients with low-grade disease in the community.

Industrial Applicability

Factors to be considered in addressing different cohorts with varying mask protection requirements for the manufacturing industry

Overall features

Material

• Bio-safety

• Availability

• Cost

Production

• Factory vs Home production

• Cost

Outer layer

Hydrophobicity/ superhydrophobicity -optional for General public

Super-hydrophobic for medical/ hospital setting is required to minimize risk of fluid/ macro-droplet splashing during procedures or close patient contact.

Structural/moldable layer

3D configuration for mask fit to face to stop leakage from the sides -optional in the non-medical setting.

Layer of added/chemical filtration.

Activated carbon retaining specific virucidal Cu nanoparticles as well as filtering chemical vapours and odours.

- filter cartridge in mask

- ventilators/ exhaust filters/ closed system (or even open system) air conditioner filters

Nano-filtration layer

Level of 300nm particle filtration eg.60%, 80%, 95%, > 95%

Number of layers eg. For ventilators.

Level of virucidal activity

Added copper nanoparticles eg. High concentration for ventilator outlets

Inner layer

Filter/limit filtration layer material from contact with the face and airway

Absorbs perspiration and condensation while preventing fluid from reaching the filtration layer.

Comfortable to face Safe, non-allergenic layer Ease of wearing

Breathability - may be conversely related to filtration efficacy.

Straps, ear loops and elastic head bands Fit to the face- cloth mask - non-medical personnel.

Configured fitting mask - HCW.

Close-fit to face - HCW in contact with suspected/ confirmed COVID-19 patients.

The invention claimed is:

1. A face mask for removing physical and / or biological impurities from inhaled and exhaled air, comprising a super-hydrophobic outer layer, a hydrophilic inner layer, a middle layer having virucidal property with mechanical disruption and electrostatic binding of the microorganisms wherein all three layers are woven and biodegradable and attached with an adjustable ear loop.

2. The face mask according to claim 1, wherein the superhydrophobic outer layer is formed by modifying cotton fabric with self-assembled stearic acid molecules on vertically-aligned titanium dioxide or zinc oxide nanotechnological architectures with hierarchical structures such as nanorods, nanoflakes and nanoflowers on the fabric surface which preserves the superhydrophobic properties at least up to 20 standard washing cycles.

3. The face mask according to claim 1, wherein the middle layer is fabricated by blocking the pores of cotton fabric using chemically attached titanium dioxide nano- and micro-particles to have required breathability but to filter particles of size equal to or greater than 300 nanometers by mechanical disruptions and electrostatic binding, and having chemically attached zinc oxide nanoparticles to induce viricidal activity.

4. The face mask according to claim 1 and 3, wherein the filtration and viricidal middle layer cotton fabric is prepared by padding the fabric in the industry with roller padders a solution containing the said titanium dioxide nano-to-micro-particles, zinc oxide nanoparticles and polyacrylate binder and an industrial softener and curing at 150 °C for 4 minutes.

5. The face mask according to claim 1, wherein the face contact innermost layer by making coton/poplin fabric superhydropliillic/hydrophilic by controlling fabric pilling by the application of an extra-thin, ~ 50 ran thick layer of a suitable polymeric material on the both sides of the fabric by spraying the polymeric solution on to the fabric surfaces or by screen printing the solution to the surfaces.

6. The face mask according to claim 1, wherein the inner layer’s hydrophilicity is achieved by using purposely developed 100% coton fabric capable of absorbing moisture and carbon dioxide in the exhaled air and quickly evaporating out to prevent accumulation of carbon dioxide rich atmosphere in the headspace between the face and the mask and to give required breathability.

7. The face mask according to claim 1, 3 and 4 wherein the middle layer is formed by chemically binding titanium dioxide microparticles to cover pores of cotton fabric down to 300 run and to electrostatically bind negatively charged viral envelope of the corona viruses including SARS CoV-2 and to destroy them by mechanically disrupting the corona virus and damaging envelopes and to destroy any bacteria by chemically bound star-shaped, rod-like or flake-like zinc oxide nanoparticles, the later is also capable of destroying viruses and bacteria by chemical and photochemical actions. The face mask according to claim 1, 3 and 4, wherein the middle layer also has enhanced electrostatic filtration is achieved due to the electrostatic binding of the negatively charged viral envelopes with positively charged titanium dioxide microparticle surfaces.

Table 1: The measured contact angles for different methods of introducing superhydrophobic properties to cloth material.

References

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2.van Doremalen, N., Bushmaker, T., Morris, D., Holbrook, M., Gamble, A., Williamson, B., Tamin, A., Harcourt, J., Thornburg, N., Gerber, S., Lloyd-Smith, J., de Wit, E. and Munster, V., 2020.

Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1. New England Journal of Medicine, 382(16), pp.1564-1567.

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Infection Prevention And Control During Health Care When Novel Coronavirus (Ncov) Infection Is Suspected, [online] Available at:

<https://www.who.int/publications-detail/infection-pre vention-and-control-during-hea lth-care-when-novel-coronavirus-(ncov)-infection-is-suspecte d-20200125> [Accessed 10 May 2020].

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Asymptomatic Transmission, The Achilles’ Heel Of Current Strategies To Control Covid-19 I NEJM. [online] Available at:

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<https://www.cdc.gov/coronavirus/2019-ncov/prevent-get ting-sick/diy-cloth-face-cover ings.html> [Accessed 10 May 2020].

6. Stability of SARS-CoV-2 in different environmental conditions DOI:

(Strikingly, a detectable level of infectious virus could still be present on the outer layer of a surgical mask on day 7 (~0·1% of the original inoculum).

7.Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1 N Engl J Med 2020; 382:1564-1567

DOI: 10.1056/NEJMc2004973

((On copper, no viable SARS-CoV-2 was measured after 4 hours and no viable SARS-CoV-1 was measured after 8 hours. On cardboard, no viable SARS-CoV-2 was measured after 24 hours and no viable SARS-CoV-1 was measured after 8 hours (Figure 1A).

April 16, 2020))

8.WHO. Infection prevention and control during health care when novel corona virus

(nCoV) infection is suspected

Interim guidance 19 March 2020 Publication

((Personal hygiene and social distancing)) 9.Asymptomatic Transmission, the Achilles’ Heel of Current Strategies to Control

Covid-19

April 24, 2020

DOI: 10.1056/NEJMe2009758

((These factors also support the case for the general public to use face masks when in crowded outdoor or indoor spaces. )) lO.Centers for Disease Control and Prevention.

Use of cloth face coverings to help slow the spread of COVID-19.

April 3, 2020 https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-si ck/cloth-face-cover.html.

6. Stability of SARS-CoV-2 in different environmental conditions DOI:

(Strikingly, a detectable level of infectious virus could still be present on the outer layer of a surgical mask on day 7 (~0·1% of the original inoculum).

7.Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1 N Engl J Med 2020; 382:1564-1567

DOI: 10.1056/NEJMc2004973

((On copper, no viable SARS-CoV-2 was measured after 4 hours and no viable SARS-CoV-1 was measured after 8 hours. On cardboard, no viable SARS-CoV-2 was measured after 24 hours and no viable SARS-CoV-1 was measured after 8 hours (Figure 1A).

April 16, 2020))

8.WHO. Infection prevention and control during health care when novel corona virus (nCoV) infection is suspected

Interim guidance 19 March 2020 Publication

((Personal hygiene and social distancing))

9.Asymptomatic Transmission, the Achilles’ Heel of Current Strategies to Control Covid-19

April 24, 2020

DOI: 10.1056/NEJMe2009758

((These factors also support the case for the general public to use face masks when in crowded outdoor or indoor spaces. )) lO.Centers for Disease Control and Prevention.

Use of cloth face coverings to help slow the spread of COVID-19. April 3, 2020 https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-si ck/cloth-face-cover.html.