3.1. Characterization studies
3.1.1. SEM Analysis
The surface morphologies of cotton fabric, recycled PET, and PP layers are provided in Fig. 4 (a-c). The surface morphology of the cotton layer shows tightly inter-woven cotton threads, which represents tight porosity. The SEM image of extracted warp knit PET layer shows a uniform and highly porous structure that aids in easy passage of air. Moreover, it can be visualized from the surface SEM image of the electro-spun PP layer that the strings of PP are interlocked in a way that it allows the passage of air leaving behind the dust, particulate matter, bacteria, and viruses.
3.1.2. Contact Angle Specifications
Additionally, the PP layer was tested for its hydrophobicity by examining the contact angle. DSA100M model Goniometer (Kruss, USA) to analyze the surface hydrophilicity by employing sessile drop technique at ambient temperature conditions.
During the course of the contact angle analysis, a water droplet was positioned on the surface of PP layer and measured within 5 sec of instant dropping for obatining an accurate value. The schematic representation of contact angle measurement is illustrated in Fig. 5 (a). The contact angle of the PP layer was found to be 121.6o, indicating high hydrophobicity that aids in effective separation of the respiratory droplets by creation of a greater threshold critical pressure to penetrate the mask, according to the Young-Laplace Eq. (1) (Liu and Cao 2016). The contact angle of the PP layer is seen in Fig. 5 (b).
$$\varDelta \text{p}= \frac{2{\gamma } \text{C}\text{o}\text{s}{\theta }}{\text{r}}$$
1
Where,\(\varDelta \text{p}\) is the pressure difference accross fluid interface, \({\gamma }\) is the surface tension and r is circular cross-sectional radius of water droplet,\({\theta }\) is the contact angle.
3.2. Experimental Results
The working mechanism of the developed facemask mainly depends on the material of construction. The motive of combing cotton textile, PET and PP layers is to create a nonlinear strenuous or tortuous path that restricts the entry of pathogens and respiratory droplets of 0.3 µm to 10 µm in size. Moreover, the mask layers are arranged in such a way that they barricade the foreign particles by molecular sieving mechanism as shown in Fig. 6 (a). Also, the rejection of particulate matter is mainly based on three principles, namely, inertial impact, diffusion, and electrostatic attraction. The dust and aerosol particles of ≥ 1µm having sufficient inertia are filtered through its outer filtration layer. The particles of 0.1−1µm exert low inertia, and flow through the mask under diffusion mechanism, but get stuck as they pass through the torturous path formed by the mask fiber matrix. On the other hand, the statically charged particles attract oppositely charged particles and filter them through a charge attraction mechanism. Figure 6 (b) illustrates the working mechanism involved in filtering the particulate matter through the developed multilayer mask.
The experiments were conducted to study the performance of the developed facemask in terms of air and water permeability, washability, BFE and PFE. After conducting the experiments, the results were calculated accordingly and discussed below.
3.2.1 Air and Water Permeability Analysis
The air and water permeability tests for the designed mask were conducted in a single-stage process. From this experiment, the air and water permeabilities of the designed mask were found to be 843496 L/m2.h and 1185 L/m2.h respectively, at an applied pressure of 0.5 bar. It can be concluded that the designed mask is highly permeable to air and resistant to water. This in turn proves that the mask is highly breathable and restricts the entry of respiratory droplets containing bacteria or viruses. Hence, further experiments on bacterial and particulate filtration can justify the overall performance of the mask.
3.2.2 Washability (Durability) Analysis
The durability analysis of the masks (indigenous, and commercial) were noted at 0, 5, 10, 20, 30 washes. The fundamental parameters like breathability, appearance, fitness, flame extinguishing capability, shape and size, and water repulsion capability were analyzed to estimate the durability of the masks. The breathability, appearance, fitness, shape and size of the mask were assessed visually by wearing the facemask. In case of the flame extinguishing test, the candle flame was tried to be blown outafter wearing the mask. In case the flame was not extinguished it meant that the droplets emanating from the respiratory system were minimum and the mask was supposed to have passed the test. In the water repulsion test, 10 mL of water was poured into the mask and holding time was recorded till the water started dripping from the mask. The photographs of flame extinguishing and water hold tests for the developed facemask are illustrated in Fig. 7 (a) and (b), respectively. From Table 1(a), it can be observed that all the parameters tested for the indigenous facemask show that the mask was intact, and not much difference in properties was observed even after 30 washes, with only a negligible changeinthe water repulsion test. In case of the commercial mask, the results in Table 1(b) reveal that the mask was unable to withstand all its properties just after 5 washes. Additionally, the commercial facemask couldn’t pass the flame extinguishing test even when it was not washed even once, and got extinguished immediately by one or two blowings (exhalation) from the mouth/nose.
3.2.3 Bacterial Filtration Efficiency
The preliminary BFE test conducted at the laboratory showed that the developed mask was able to reject 87% bacteria. As discussed in the methodology section, after incubation of the nutrient agar plates for 24 h, both the uncovered plate and plate with mask were placed under an illuminated colony counter and the number of colonies were noted. It was witnessed that the uncovered plate had 31 bacterial colonies, while the plate covered with mask had only 4 bacterial colonies, which corresponds to 87% rejection. Figures 8 (a) and (b) presents the uncovered and mask covered nutrient agar plates with bacterial colonies, respectively. Thus, the indigenous bacterial filtration test revealed that the designed multilayered facemask is highly efficient in rejecting aerobic bacteria from passing through.
3.2.4. Particulate Filtration Efficiency
The preliminary particulate filtration test was conducted by injecting fine uniform particulates under both air and water mediums. From Figs. 9 (a) and (b), it can be clearly witnessed that no particulate matter passed through the developed multilayered facemask under both air and water media.
3.2.5 Validation of designed multilayered facemask
The developed multilayered facemask was validated as per the ASTM methods discussed in the methodology section. Table 2 represents the results obtained from SITRA, which shows that the developed multilayered mask exhibits high breathability, splash resistance and excellent BFE and PFE.
Table 2
SITRA analysis data for the designed facemask
Parameter
|
Value
|
Flammability (> 5 seconds)
|
Passed with 38.8 seconds
|
Breathability (Pa/cm2)
|
211.01
|
Splash Resistance
|
Pass
|
Bacterial Filtration Efficiency (%)
|
95.7
|
Particulate Filtration Efficiency (%)
|
83.57
|
3.2.6 Economic viability of the designed facemask
The designed multilayered facemask has been evaluated for the total expenses required for manufacturing an individual mask. In this context, a detailed cost estimation analysis has been carried out to assess the commercial feasibility of the mask. The materials used for the design of multilayered masks are easily available in the market and the costs for a unit piece are provided in Table 3.
Table 3
Cost estimation for the designed multilayered SaanS facemask
Name of Component
|
Price (in Rs)
|
Recycled PET layer
|
6.18
|
PP Layer
|
3.78
|
Textile Fabric (2 Layers)
|
1.98
|
Elastic Bands
|
0.8
|
Deionized Water
|
0.004
|
Amenities (Including stitching charges)
|
3.5
|
Beads
|
0.62
|
Total Cost per Mask (Rs.)
|
16.884 (0.21 USD)
|
The cost incurred for PET layer includes the charges for extraction and cleaning of PET spacer from waste RO membranes. From the above economic analysis, it can be concluded that the developed multilayer facemask is affordable for the common population.
3.2.7. Comparison between the indigenous SaanS facemask and commercial N95 facemask
The efficacy of the mask was well-compared with the commercially available N95 mask in terms of reusability, hydrophobicity, air permeability, water permeability, tortuosity, % BFE, and affordability. Table 4 (a) presents the technical assessment of the indigenous and commercial facemask. It can be depicted that the commercial N95 mask has very less reusable properties whereas the indigenously developed mask proved to be reusable. On the other hand, the use of PET and PP layers in the indigenous masks gives added hydrophobic characteristics with high repulsion to respiratory droplets, unlike the commercial mask having only a PP layer. Moreover, the air permeability of the designed mask is almost 2.2 times greater than the commercial mask ensuring high breathability and comfort making it especially suitable during long hours of usage for frontline Covid warriors. The combination of PET and PP lamina along with cotton textile provided high tortuosity and low water permeability to ensure high rejection of particulate matter. On the whole, the indigenous mask is technically superior, washable, and economical.
Table 4
(a): Technical comparison of the indigenous and N95 mask
Properties
|
Indigenous Mask
|
Commercial N95 Mask
|
Reusability
|
High (Washable texture)
|
Low
|
Hydrophobicity
|
High (PET and PP Layers)
|
High (PP Layer)
|
Air Permeability *
|
High (843496 Lit/m2.hr)
|
Low (384250 Lit/m2.hr)
|
Water Permeability *
|
Low (1185 Lit/m2.hr)
|
Moderate (3156 Lit/m2.hr)
|
Tortuosity
|
High (More no. of layers)
|
Low
|
% Bacterial Filtration Efficiency
|
95.7
|
95–98%
|
Non-Return Valve
|
No Valve, for Better Safety
|
Valve is provided
|
Affordability
|
Rs. 17/- (0.21 USD)
|
Rs. 100/- to 300/- (1.26 to 3.77 USD)
|
*Tested at 0.5 gauge pressure and 28 ± 2 ºC temperature |
Table 4 (b) presents the general properties and filtration efficiency data of the indigenous SaanS mask and the various commercially available branded masks. In this study, the commercial N95 grade facemasks consisting of 3 to 6 layers were chosen for proper comparison. It can be seen that the N95 brand facemasks available in the market costfrom Rs 100 to 500, in which the Impulse branded mask is the lowest priced reusable mask at Rs 100. The key advantage of the indigenously developed mask lies in the cost of manufacturing of just around Rs 17, which can be sold at a 100% margin of Rs 35; making it quite cheaper than the commercial mask. From this comparison, it can be witnessed that the indigenous mask hasmore advantagesover the branded masks.
Table 4
(b): Overall comparison between indigenous SaanS facemasks and the commercial branded masks
Company
|
CSIR-IICT
|
Khadi Essentials
|
Wildcraft
|
Impulse
|
Clovia
|
CP-MED
|
Aero
|
No. of layers
|
4
|
5
|
6
|
4
|
3
|
5
|
5
|
Cost
|
17/-
|
200/-
|
150/-
|
100/-
|
288/-
|
500/-
|
165/
|
Usage & Comfort
|
Continuous usage owing to its ease of breathability and lightweight material
|
Used in hot and cold conditions
|
Low heat build-up
|
High temperature resistant
|
Extremely lightweight
|
Continuous usage up to 8 h
|
Several hours of uninterrupted usage
|
Reusability
|
Reusable after gentle hand wash
|
Reusable
|
Reusable with gentle hand wash
|
Reusable and washable
|
Dispose off after use
|
Disposable
|
Disinfection for reuse
|
Anti-microbial Layer
|
Hydrophobic PP layers
|
Activated carbon
|
Melt blown layers
|
Bacterial filter
|
Non-woven melted blown
|
Melt-blown fabric
|
Activated Carbon Air Filter
|
Grade
|
95.7% bacterial filtration efficiency
|
N95 (bacterial resistance 95%)
|
W95 (bacterial resistance 95%)
|
I95 (bacterial resistance 95%)
|
N95 (bacterial resistance 95%)
|
KN95 (> 95% non-oil-based particle)
|
N95 (95% filtration efficiency)
|
3.2.8. Free distribution of the developed masks in schools, hospitals, villages, and orphanages
Furthermore, with the help of Cipla Foundation, Mumbai, several NGOs could access IICT’s facemask technology to attain financial support for procurement of capital machinery and materials required for manufacturing 1 lakh masks for free distribution as part of societal welfare. In that course of time, the authors have conducted online training sessions to NGOs and start-up companies. The pictures of the online training are shown in Fig. 10 (a). These programs helped in the manufacturing of developed multilayered masks, which were distributed in and around 30 schools, 2 hospitals, and a few orphanages across 57 villages that covered 26 districts in the States of Telangana, Andhra Pradesh, Karnataka, and Maharashtra. The photographs of mask distribution to the common people and children in villages and orphanages are shown in Fig. 10 (b) and (c), respectively. Also, the online sessions aided in attaining sustainability goals by providing elderly support, social inclusion, and partnership in action.
3.2.9. Commercialization and business analysis:
As the pandemic affected population of all races, religions, and communities across the globe, there was a need for bulk production of affordable and reusable masks. A few reusable masks that are available in the market are too pricey for the common people to purchase, especially in developing countries. Thus, as a key to public protection, the indigenous affordable mask was commercialized and made available in the market with the brand name “SaanS”. Unlike other masks, the developed facemask follows green technology process as it can be recycled with zero waste discharge as mentioned in the leaflet shown in Fig. 11. The mask is sterilized before disposal and then segregated into the four layers. The cotton layers are incinertaed while the PET and PP layers are recycled back as as reusable plastic for mixing with coal tar in road construction etc. Hence, keeping in the view of the common people and frontline sanitization workers, the multilayered cost-effective mask was introduced in the market. To meet the demand, CSIR-IICT moved its novel mask technology concept to market place and thereby transferred this technology to a few NGOs, namely, Ambuja Cement Foundation at Himachal Pradesh, Mann Deshi Foundation based at Pune, HelpAge India in Bihar and Pondicherry states, Halo Medical Foundation in Pune, Divya Disha, Hyderabad and one start-up named Khar Energy Optimizers, Hyderabad. The technologywas transferred to the NGOs exclusively for the manufacture and supply of the multilayered protective facemasks to frontline warriors at an affordable price. Thus, through this scheme, the motive towards sustainability was attained by financial literacy, and preventive healthcare measures. The commercialization of these masks through the foresaid NGOs created rural employment and empowerment that provided elderly support and livelihood generation. On the whole, in the period of August 2020-22, the total number of masks produced are 6,49,259 and total number of masks sold stood at 5,60,593. This in turn generateda revenue of 19.32 million rupees (242906.97 USD) and created employment to 500 women and elderly people, whose livelihood had earlier been impacted by the pandemic. The details of the NGOs, their mask production and sales are mentioned in Table 5.
Table 5
Summary of Masks Production, Revenue Earned, and Employment Generated (Business data)
Name of the partner
|
Location
|
Total No. of masks produced
|
Total No. of masks sold
|
Total revenue generated
(Million Rupees)
|
Total nos. of women/elderly impacted through livelihood
|
Maandeshi Foundation
|
Pune & Satara
|
86,450
|
58,665
|
1.85
|
100
|
Halo Medical Foundation
|
Andur
|
86,504
|
79,061
|
2.27
|
15
|
Lohara
|
73,644
|
100,750
|
2.01
|
15
|
Ambuja Cement Foundation
|
Nalagarh (H.P.)
|
73,000
|
70,608
|
2.11
|
10
|
Surat
|
18,807
|
17,707
|
0.53
|
8
|
HelpAge India
|
Supaul
|
224,753
|
166,422
|
6.65
|
250
|
Cuddalore
|
103,885
|
97,380
|
3.87
|
102
|
Total
|
8 locations
|
6,49,259
|
5,60,593
|
19.32
|
500
|