key: cord-0764689-1unvf45t
authors: Ishack, Stephanie; Lipner, Shari R.
title: Applications of 3D Printing Technology to Address COVID-19 Related Supply Shortages
date: 2020-04-21
journal: Am J Med
DOI: 10.1016/j.amjmed.2020.04.002
sha: 219b00f06e8adee6c482aabf676fa8cebdc884d8
doc_id: 764689
cord_uid: 1unvf45t

nan

China on December 8, 2019. Globally, the number of affected COVID-19 patients is growing exponentially, with the death toll exceeding 27,300 as of March 27, 2020. Worldwide, there is a limited supply of N95 respirator masks, face shields, ventilator valves, testing kits and other personal protective equipment (1) (2) . Thus, adequate production and distribution of personal protective equipment is critical during this pandemic. To address these shortages, threedimensional (3D) printing, a novel and innovative technology used to fabricate complex architectures, is well suited. 3D printing is an adjustable, robotic platform allowing for tailored deposition of biomaterials using computer-aided design systems to formulate layer-by-layer custom designs with controlled architecture and composition (3) (4) (5) (6) (7) .

N95 respirators masks have two advantages over surgical, paper or cloth masks: 1) they are >95% efficient at filtering 0.3-µm airborne particles and 2) they are fit tested to each user to ensure an adequate seal, such that air and small droplets do not enter around the edges of the mask and into the health care worker's breathing zone (4) . The Centers for Disease Control and Prevention recommends N95 masks for health care workers taking care of patients with COVID-19.

3D printing can be used to produce tailored seal designs for improving mask comfort and fit. To customize face mask seals, 3D laser scanning can be implemented to scan exact facial parameters, with a tailored and customized face seal N95 template. Anthropometric data of the chin arc, jawline, face and nose lengths, and nose protrusion measurements can be taken into account with this customized seal. In a study using face seal prototypes with Acrylonitrile Butadiene Styrene plastic using a Fused Deposition Modeling 3D printer, three subjects showed improved contact pressure compared with use of 3M© 8210 N95 FFR respirator masks (4).

Moreover, a personalized mask may account for facial hair length and density for a more precise fit.

Standard N95 masks consist of filtration material composed of electrostatic non-woven polypropylene (PP) fibers which are semi-rigid, lightweight and fatigue resistant. The semicrystalline structure may cause significant distortion of the 3D printed parts upon cooling thereby making 3D printing difficult. Material extrusion 3D printing was used to design a 3D printable thermoplastic elastomeric material from a blend of polypropylene (PP) and styrene-(ethylenebutylene)-styrene (SEBS) (5) . This blend provides better printability and flexibility for N95 mask design. PP is commonly used for various industrial applications due to its low cost, processability, printability, recyclability and mechanical integrity. SEBS is a polymeric elastomer with low processing temperature and low distortion during extrusion (5) . Thus, the PP/SEBS combination would improve the processability of 3D printed N95 masks. Moreover, controlling the thermoplastic elastomer ratio allows for tailoring the flexibility and elasticity of the 3D model material for better fitted masks. 3D melt electrospinning printing can also be used to create PP microfibers with sequential layering to accurately obtain a 3D form (3, 6) . Thus, 3D printing procedures may allow for the creation of stable and biocompatible N95 masks that are comparable to industrial manufacturing brands. Figure 1 displays a potential N95 3D printed mask prototype.

Polycarbonate and polyester, polyvinyl chloride and other synthetic polymers are commonly used to make surgical face shields (6) . These biomaterials are transparent, lightweight and provide high optical clarity. The polymers can easily be printed using 3D technology to meet the needs of healthcare workers treating COVID-19.

Creating 3D printed test swabs would help increase COVID-19 testing capacity.

Nasopharyngeal and oropharyngeal swabs can be made from a flexible polymer, using polystyrene for the shaft. The tip can be tailored to be micro fine using computer-aided design software. Thereafter, swab bud lattice fibers can be made from calcium alginate using hydrogels using 3D tissue engineering (3, 6) .

Ventilator valves are attachments used to deliver oxygen at fixed concentrations for patients with acute respiratory distress, including COVID-19 patients. 3D printing technology can be used via a filament extrusion system or a polymer-laser powder bed fusion process to print single-use valve sets. 3D printers can design the different elements of the valve using biomaterials such as polyamide and polysulfone, polycarbonate, silicone rubber and stainless steel (6) . Furthermore, these disposable valves eliminate time-consuming sterilization.

3D printing techniques, such as fused filament, inkjet, extrusion and powder extrusion, allow for fabrication of 3D printed pills. Medication-printing technologies typically utilize a small nozzle to lay thin disc-shaped layers of powders and deposit microscopic droplets of liquid to bind the materials. A coaxial needle extrusion 3D technology was used to print active pharmaceutical ingredients and create combinations of controlled dosing of drugs (7) . While there are no specific antivirals or vaccines for treatment of COVID-19, several well-characterized anti-viral drugs are being considered as therapies (2) . It may be possible to use 3D medication-printing technology to effectively and rapidly print lopinavir/ritonavir, chloroquine, and hydroxychloroquine pills. Thus, 3D technology has the potential to revolutionize the pharmaceutical industry, making drug research, development and production applicable to COVID-19 patients.

As the COVID-19 outbreak rapidly evolves, there has been a personal protective equipment shortage globally. 3D printing inventions can be rapidly applied to address these deficiencies (1-2). Cost, processing time, testing, and manpower are potential barriers to creating 3D-printed personal protective equipment. However, the synthetic polymer biomaterials needed for 3D-printed personal protective equipment are exact or very similar in composition to the standard manufacturing grade products (i.e. N95 masks provides the same fluid barrier and air filtration protection) (4-6). Moreover, these synthetic polymer materials are readily available and cost effective (i.e. polypropylene is 12.47 cents per pound). 3D printer costs vary but are an excellent investment with labor performed via robotics. In conjunction with flattening the curve via social distancing, this pioneering technology can provide adequate personal protective equipment for health care workers on the front lines of this pandemic. 

Critical Supply Shortages -The Need for Ventilators and Personal Protective Equipment during the Covid-19 Pandemic. NEJM

Evaluation and Treatment Coronavirus (COVID-19)

A Review of 3-Dimensional Skin Bioprinting Techniques: Applications, Approaches, and Trends. Dermatol Surg

Customized design and 3D printing of face seal for an N95 filtering facepiece respirator

3D-Printable PP/SEBS Thermoplastic Elastomeric Blends: Preparation and Properties. Polymers (Basel)

3D printing and characterization of a soft and biostable elastomer with high flexibility and strength for biomedical applications

A Feasibility Study of an Extrusion-Based Fabrication Process for Personalized Drugs

Styrene-(ethylene-butylene)-styrene (SEBS)