3D Printing a Human Being Notes

Basic Principles of 3D Printing Technology

  • 3D printing is also known as Additive Manufacturing.
  • It builds up a 3D object one layer at a time.
  • The first 3D printers were invented in the 1980s.
  • all3dp.com is an excellent resource to learn about 3D printing.

Why the Increasing Interest in 3D Printing?

  • The cost of this technology has rapidly decreased over the last 10 years.
  • Thousands of different 3D printers are available.
  • Starting at < £99.

3D Printer Types

  • Material Extrusion – Fused Deposition Modeling (FDM) / Fused Filament Fabrication (FFF)
    • Solid-Liquid-Solid
  • VAT Polymerisation – SLA / DLP
    • Liquid-Solid
  • Powder Bed Fusion – SLS
    • Solid-Liquid-Solid

3D Printer Specifications

  • Materials:
    • Hard – PLA, ABS, nylon, acrylic, metals, concrete
    • Soft – TPU, silicone, clay
    • Organic – chocolate, icing, cellular
    • >50 different materials types available
  • Layer thickness – 100100 microns
  • In-plane resolution – 100100 microns
  • Speed – 10 mins to days depending on object size.

3D Printing Pipeline

  • The pipeline consists of:
    • Source Data (CAD, Surface Scan, Medical Imaging)
    • 3D File (STL)
    • Slicer
    • 3D Printer
    • 3D Print
    • GCODE File
    • Segmentation

3D Printing at King’s Health Partners

  • There are dedicated 3D printing facilities within KHP to support:
    • Clinical applications – numerous routine services
    • Research – medical devices, anthropomorphic phantoms, implants
    • Education – dedicated modules that teach additive manufacturing to engineering and healthcare students (year 2 Synthetic Anatomy)
  • The Medical Physics Department has a dedicated 3D Printing Centre that handles production of 3D printed models as a clinical service and for research.

Clinical Services

  • Production of cardiac models for surgical planning in patients with congenital heart disease (CHD).
    • Valverde et al. 2017, Eu. J. Cardiothorac. Surg.
      • 10 international centers
      • 40 patients with complex CHD
      • 19/40 – models helped to refine surgical approach
      • 21/40 – models did not alter the surgical approach
    • 3D Printer: Stratasys Objet500 – material jetting multi-material

Research – Anthropomorphic Phantoms

  • These can be used for:
    • Testing of novel medical devices
    • Generation of synthetic medical images for training of AI algorithms
    • Surgical procedure simulation for training & rehearsal
    • Validation of biophysical modelling algorithms
    • Reduce the need for patient data
    • Reduce the need for animal experiments
    • Reduce the need for cadaver experiments
    • Reduce costs

Anthropomorphic Phantoms – Cardiac Phantoms

  • Whole-heart models using soft materials.
    • Lay-fomm 40
    • Tango Plus
  • Material:
  • Printer:
    • Flsun Delta FDM
    • Stratasys Objet500 PolyJet
  • Cost:
    • £30
    • £750
  • Shu Wang et al. 2020, J. 3DP&AM

Anthropomorphic Phantoms – Valve Phantoms

  • Valve models using 2-part molds & silicone
    • (a) External Mold; (b) Internal Mold; (c) Silicone Injection; (d) Final Fabricated Valve
  • Manufactured silicone valves, closed on top, and open on the bottom (a) normal valve (b) rheumatic valve (c) calcified valve and (d) bicuspid valve
  • Ultrasound images of (a) normal valve (b) rheumatic valve (c) calcified valve and (d) bicuspid valve; MR images of (e) normal valve (f) rheumatic valve (g) calcified valve and (h) bicuspid valve
  • Gill et al. 2023, JCTR Flow Rig

Anthropomorphic Phantoms – Direct Silicone Printing

  • Direct silicone printing of valve models
    • Molded Valve - Ecoflex 0030
    • Directly Printed Valve - Dragonskin 20
  • Custom Silicone Printer: based on Prusa i3 clone and open-source design
    • LOW COST
    • LARGE BUILD VOLUME
    • REDUCED MANUFACTURING TIME

Implants – Bone Replacement

  • For lung cancer surgery – patients with bone involvement
    • CT → 3D Model
    • Low-cost PLA Print
    • Low-cost Silicone Mold → Custom PMMA Implant
  • LOW COST vs TITANIUM IMPLANTS
    • 15+ Patients implanted so far
    • No complications
    • Better respiratory mechanics & improved aesthetics
  • Pontiki et al. 2021, ATS

What is 3D Bioprinting and Why do we need this?

  • 3D Bioprinting involves the use of living components to print tissues and organs
    1. Print 3D Scaffold Seed with Cells
    2. Bioink Print Cells Only Print Cells + Scaffold (usually a hydrogel)
  • Could be useful for research, testing of drugs/devices and implants
  • Shinkar & Rhode, Annals of 3D Printed Medicine, 2022

3D Printing with Bioinks

  • The process includes:
    • Pre-processing
      • Imaging (X-ray, MRI, CT, Ultrasound)
      • 3D Modeling & Slicing
      • CT Image to 3D Model STL File
    • Bioink Preparation
      • Harvesting Patient's cells
      • Cell culture
      • Cell-laden bioink preparation
    • 3D Bioprinter
    • Post-processing
      • Bioreactor for tissue maturation
      • Matured tissue / organ
    • Application
      • In vitro models for disease modelling, drug/cosmetic testing
      • Transplanted into patients
  • Vijayavenkataramana et al, Advanced Drug Delivery Reviews 2018

Examples of 3D Bioprinting - Skin

  • Bioink with Fibroblasts + Keratinocytes
  • 3D Bioprinted skin
  • Pourchet et al, Advanced Healthcare Materials 2016

Examples of 3D Bioprinting – Heart Muscle

  • Bioink with Myocytes Functional Patch of Myocardium
  • Many other structures have been bioprinted – liver, heart valves, blood vessels, trachea
  • Gaetani et al, Biomaterials 2015

Summary

  • The development of 3D printing technologies will have a huge impact on healthcare.
  • Already used for medical devices, surgical planning, implants and research.
  • Bioprinting is a booming research area.
  • Printing of tissues & organs is challenging but progress is rapid.
  • We need to consider ethical issues.