How Plastics Can Boost 3D-Printing of Medical Devices

Published on 31 Jul, 2017

The wide usage of plastics, especially photopolymers, can evidently unlock the great potential, in terms of applications, of 3D printing of medical devices.

In the recent years, 3D printing technology has gained phenomenal traction in the medical and healthcare industry. The medical industry is seeing mushrooming applications of 3D printing, such as tissue and organ fabrication, the creation of customized prosthetics, implants, and anatomical models, personalized medicines, medical devices, and tools.

Traditionally, research and development in the medical devices market has always been highly dependent upon the ever evolving stringent regulations implemented by countries to safeguard end-user/patients health. Manufacturers have been incurring significant development costs to test and produce medical devices compliant with such ever changing regulations. With 3D printing technology, one is able to rapidly provide customized medical products as per the patient’s anatomy despite strict regulations, which was difficult to be implemented earlier.

Factors fuelling the significant growth in 3D printed medical devices market can be segregated into two broad categories i.e. economic (cost effectiveness, customizable manufacturing and accelerating development of clinical trial-ready devices) and lifestyle related (rise in vascular, osteoarthritis diseases and geriatric population in the developed world).

Globally 3D printed medical devices market is expected to be worth USD 1.4 billion by 2026, enjoying a 17.7% growth for the period 2016-2026. In terms of market segmentation, “plastics” is most commonly used material for 3D printed medical devices and accounts for 72% share (2016). At the same time, regional adoption and demand for 3D printed medical devices is highly lucrative in the North America (especially USA, accounting for 45% share as of 2016), but this spread is expected to change with pockets of demand emerging in regions such as European (Germany, UK, France) and APAC (Japan, China), led by constructive government initiatives and financial support for further developing medical device applications via 3D printing technology.


Plastics Rule

Broadly, the main 3D printing technologies used for manufacturing of medical devices (such as orthopaedic, dental, and internal and external prosthetics) are stereolithography (SLA), selective layer sintering (SLS), digital light processing (DLP), fused deposition modelling (FDM), polyjet/inkjet 3D printing, and electronic beam melting (EBM).

While titanium, nylon, ceramic and metals are quite commonly used materials across the various 3D printing technologies, plastics happen to be the most widely used feed material to produce medical devices using 3D printing. Use of plastic in medical devices accounted for 72% market share of the global 3D printed medical devices market in 2016. The plastic material segment is expected to reach a value of $984.7 million by 2026, registering a CAGR of 17.2% from 2016 – 2026.

Thermoplastics and photopolymers are the two types of plastics used for 3D printing of medical devices.

  • Thermoplastics: Simply put, thermoplastics are polymers that soften when they are heated and solidify as they cool.
  • Photopolymers: Photopolymers are sensitive to light, as when exposed to light these polymers alter their physical properties. The most common examples of such photopolymers are the typical liquid plastic resins that harden when exposed to light source such as a laser, lamp, projector or light-emitting diodes (LEDs). Photoinitiators, when exposed to light, transform light energy into chemical energy, creating oligomer or commonly known as binders, and monomer mixture to create three-dimensional polymer networks. 

Here’s a quick snapshot of the comparatives between the two polymers:

Parameters
Thermoplastic
Photopolymer

Aesthetics

Produces layer lines on device, but these lines usually do not affect a device’s strength or functionality

Aesthetics achieved are of high quality

Device Size

Large parts can be manufactured separately on different workstations and can be merged to provide enough strength and functionality to behave as a single unit.

Photopolymers are suitable for high-resolution, ultra-fine parts.

Color

Usually, PLA or ABS or nylon or a wide variety of PLA blends available in various colors is used.

Photopolymer resins are proprietary and cannot be exchanged between printers of a different make. The choice of color is limited.

Precision and Smoothness

As the bonding force between the layers is lower and the weight of upper layers weighs down on the layers below, precision and surface finish is low.

Smoother surface finish is achieved as less force is applied to the model during printing.

Adhesion/Removal after 3D Printing

Printed objects can be easily removed.

Tough to remove printed objects. However few companies have researched use of oxygen to create a dead zone around the printed models (prevents hardening of resin at the surface.)

Post-processing

Need to remove supports excess plastics with the tool. Sanding is required to make surface smooth

Covered in sticky resin that has to be removed in a bath of isopropyl alcohol with the help of rubber gloves

Cost

Cheaper

Costlier

Of the two, photopolymers offer more benefits over thermoplastics and hence represent the largest market segment in the 3D printing materials market.


Photopolymers Gaining Ground

The properties and advantages of photopolymers over thermopolymers/thermoplastic polymers vary with respect to the properties of each polymer used during its synthesis. A thermoplastic polymer will have low Young’s modulus, slippery surface, and low thermal resistance. In contrast, a photopolymer, depending on the molar mass of monomer, will have improved thermal resistance, improved elasticity, higher impact strength, biocompatibility, and better surface finish.

In general, epoxies, oxetane, and acrylate resins were identified to be commonly used photopolymers, of which acrylate resins were preferred over epoxy resins, for 3D printing of medical devices, due to higher cytotoxicity and low curing time.

Recent Researched Photopolymers:

Here are certain kinds of photopolymers that have been recently researched:

  • CeraMAX: It’s a ceramic-reinforced composite that has good temperature, chemical, moisture, and abrasion resistance, which can be used as a replacement for metals due to its high speed and low manufacturing cost.
  • Photopolymer filled with Ceramic material: The materials are made up of the photocurable organic part (binder) and the inorganic filler. When the material is printed, debinding process takes place where the binder is burnt out, and the sintering process sets in where the filler is heated to densify. These ceramics are most often used for either resorbable or permanent bone implants.
  • Resins for 3D Printing Microscopic Parts: With a process called two-photon polymerization, where a high-powered laser directs two near-infrared (NIR) light photons in ultrashort pulses at photocurable resin such as negative-tone SU-8 or positive-tone AZ resins, it’s now possible to fabricate the smallest 3D-printed parts ever made. A German company called Nanoscribe has made this offering commercially available.
  • Ultrafast 3D Printing Resins EPU 60: Carbon, a US-based company, has developed lightning-fast CLIP technology, which can produce engineering-grade parts within minutes. It uses an oxygen-permeable window to print in a layerless fashion quickly. Traditionally the parts used to be not isotropic, i.e. the parts have different mechanical properties in different directions. The mechanical shortcomings of the traditional photopolymers are overcome with the use of the Carbon’s photopolymers comprising a second reactive chemistry.

Key players in the market are employing varied strategies and launching novel products keeping themselves ahead of the competition curve. For instance, Stratasys provides models to help reduce operating room time and plan surgeries before-hand. Using patient scans, relevant models are produced for the surgeon to refine the therapeutic approach prior to conducting the surgery. Superior educational training can also be conducted using 3D printed models, helping medical practitioners and students rely less on animal models, but actually work on models which mirror the complexities of the human body.

Photopolymers seems to be gaining traction in future as there are various new developments taking place around the properties of different materials and its applications. This will surely spur more medical devices manufacturers to embrace the 3D printing technology, which is likely to encourage product enhancements and a unique ‘cloud based manufacturing model’ whereby personalized medical devices can be made to order from OEMs tied up with hospitals and shipped directly to point of use.  While we have barely scratched the surface in terms of its applications, the wide usage of plastics, especially the photopolymers, shall evidently unlock the great potential of 3D printing of medical devices.


This post first appeared on SpecialChem.com.




Speak your Mind