Next Generation Bioresorbable Materials for 3D Printing Implantable Medical Devices

3D Printing Approaches Overview:

3D printing (additive manufacturing) processes produce three-dimensional parts through addition of material in a layer by layer fashion. Resorbable materials may be 3D printed using a variety of approaches including fused filament fabrication (FFF), selective laser sintering (SLS), and resin-based methods such as stereolithography (SLA) and dynamic light processing (DLP).

FFF produces parts by melting a continuous thermoplastic filament via extrusion through a heated printer head. Although the most widely utilized 3D printing technology, FFF also exhibits the lowest resolution with most printers requiring minimum layers heights ~100 microns and maximum XY resolution ~250 microns. SLS creates parts by sintering powdered materials with a laser to near-melting temperatures which causes the powder particles to fuse together to form a solid structure. SLS exhibits medium printing resolution most printers requiring minimum layer heights ~60 microns and maximum XY resolution ~80 microns. SLA produces parts through a photopolymerization process where a UV laser is focused on a photopolymer vat. SLA exhibits the highest resolution of the described methods with a minimum layer height ~50 microns and maximum XY resolution ~50 microns. Bioresorbable 3D printing materials are available for FFF, SLS, and more recently SLA-based printing methods.

3D Printing Unlocks New Design Architectures for Tissue Scaffolds:

Traditional injection molded parts are limited to solid infill designs due to the requirement resin flowing throughout a mold. In contrast, 3D printing allows for complex infill geometries such as the gyroid and honeycomb patterns to alter both the mechanical properties and cellular infiltration into the device based on its intended use. Additionally, utilization of bioresorbable materials allows for the device to maintain mechanical strength while it is needed, and to degrade into constituents that may be metabolized or excreted once the healing process has sufficiently progressed.

Figure 1A-F: A catalog of infill patterns are accessible via 3D printing that are not accessible via traditional injection molding approaches. These patterns include but are not limited to A) line, B) gyroid, C) octlet, D) concentric, E) tri-hexagon, and F) grid infill designs (Images from Xometry.com).

FFF 3D Printing versus Micro Injection Molding Bioresorbable Devices:

Micro-injection molding is a manufacturing process capable of producing parts between 0.1- 1 gram with tolerances ranging from 10-100 μm. As with traditional injection molding, design changes to the part mold may be prohibitively expensive with each mold costing ~$10,000 for low-volume/simple molds and up to $100,000 to high volume molds. Given the high barrier to entrance into injection molding, PMI’s FFF filament line of materials offers biomedical engineers the ability to iteratively test bioresorbable medical devices designs quickly and cost effectively. Additionally, PMI’s FFF filament materials are offered in standard 1.75 mm formats that are compatible with most open source FFF printers. For volumes applicable to many implantable medical devices, FFF printing is an economical alternative to injection that opens new design features to be imparted better suited for bioabsorbable implants.

Figure 2A-F: Poly-Med offers a catalog of off-the-shelf bioabsorbable filaments for FFF 3D printing. Available materials include A) Max-Prene® 955, B) Dioxaprene® 100M, C) Lactoprene® 100M, D) Strataprene® 5525, and Caproprene® 100M, as well as custom material extrusions.

Poly-Med’s now offers Photoset® Resin for Photo-Polymerization 3D Printing Methods:

Poly-Med’s team of material scientists have developed first-in-class bioresorbable fast-degrading resins for photopolymerization 3D printing methods that include SLA, DLP, and two (2) photon polymerization. In contrast to the limited bioresorbable 3D printing resins currently available, Poly-Med’s Photoset® resin product line utilizes monomeric constituents that have used in medical devices for over forty (40) years and are anticipated to be biocompatible with the data collected to date. Additionally, Poly-Med’s material scientists can tune the Photoset® resin mechanical properties and degradation timeline to best meet a device’s requirements. 3D printing with Poly-Med’s Photoset® resin allows for unparalleled resolution when manufacturing bioresorbable medical implants that require small design features.

Figure 3: Examples of model parts printed with Poly-Med’s Photoset® bioabsorbable resin. The Photoset® resin formulation may be customized to the mechanical requirements and degradation profile necessary for a particular implantable medical device.

Poly-Med’s 3D Printing Services:

In addition to supplying materials, Poly-Med also offers design engineering and 3D printing services for parts made of FFF and SLA materials. Whether a design is not in its final iteration and consultation is needed or if a part design has been finalized and prototypes are needed for testing, Poly-Med’s design engineering is available to provide requested services.

As the leader in bioresorbable medical device manufacturing, Poly-Med offers development services for 3D printing, electrospinning, extrusion, and textiles in a certified ISO Class 8 cleanroom. Poly-Med facilities are certified to meet ISO: 13485:2016 standards for quality management of its design, development, and manufacturing of bioresorbable polymers, fibers, sutures, medical textiles, and biomedical products. Connect with Poly-Med today to learn more about 3D printing your next generation bioresorbable device by contacting sales@poly-med.com!