Direct 3D printing of two-component silicone

The Problem

 

Facial/body prostheses are often required for patients who have lost facial/body parts, such as an ear, nose, eye, finger, hand or breast. These defects can result from trauma, congenital malformations or diseases such as cancer. Improvements in medicine, surgical techniques and in particular cancer survival rates are resulting in increasing numbers of patients who require prostheses.

 

Typically, facial/body prostheses are manufactured by a lengthy multi-step process that involves taking an impression from the patient, hand carving the missing defect, creating a two or three part stone mould into which pigmented silicone is placed, colour matched to the surrounding tissue. These methods of prosthesis construction are time-consuming, involving five to six patient visits and results are dependent on the skills of the prosthetist.

 

 

The Solution

 

The system being developed by Dr Trevor Coward (Reader in Maxillofacial and Craniofacial Rehabilitation at the university's Dental Institute) and his student, Swati Jindal, is unique in its ability to 3D print a biocompatible two-part silicone required for medical devices such as prostheses. Silicone formulations have been developed and printed using a modified 3D printer with a custom print head to create room-temperature curing silicone objects with properties similar to those required for prostheses. At present the system can read image files to print prosthetic noses and ears.

 

The external collaborators and co-inventors on this project are Dr Jim Smay of Oklahoma State University (responsible for the design of the mixing print head for silicone printing and its control software) and Prof Mark Waters of Technovent Ltd (developing compositions for biocompatible room-temperature curing silicones with suitable properties).

 

Figure 1: A side view of the 3D printer head according to one embodiment of the invention

 

 

Table 1. Illustrates the mechanical properties of different silicone elastomer compositions with varying cross-linker % according to embodiments of the present invention, as compared with the mechanical properties of commercial silicones (M511 Maxillofacial Silicone and TechSil Industrial Silicone)

 

 

Applications

 

The ability to 3D print biocompatible silicone presents a number of potentially significant product opportunities. These include:

  • body surface prostheses to replace missing non-articulated body parts (nose, ear, cheek, breast etc.)
  • patient specific coverings for prosthetic limbs.
  • patient specific anatomical models to enable surgeons to improve pre-operative planning of complex surgical procedures (e.g. to correct congenital abnormalities or to reconstruct following trauma).
  • patient specific biocompatible in vivo medical devices or medical device components, where advanced silicones would be appropriate.

 

 

Benefits

 

Healthcare providers can capture images of patients’ defects during one appointment using stereophotogrammetry to create digital files of the defect which can be manipulated using CAD and delivered to 3D printers by control software to produce finished prosthetic components which can then be fitted at a subsequent appointment. 

 

Benefits include:

  • fewer patient visits required;
  • significant resource savings to providers;
  • prostheses that are repeatable, precise and less dependent upon artistic interpretation by the operator;
  • physical properties of a silicone component can vary across the item: mimicking textural properties of bone, cartilage, soft tissue.

 

 

Opportunity

 

Initially, the collaborators are seeking partners wishing to further develop and commercialise the technology for supplying facial/body prostheses.  This could be through and hardware and consumables supply model or via a service provision model.  The IP owners are also open to licensing the technology for application to other fields, and are willing to grant options and evaluation licences. Field exclusivity is possible for suitable partners.

 

 

IP Status

 

Priority patent applications were filed in the USA, with the earlier dated 14 Jan 2015.  An International PCT application (with Application Number PCT/GB2015/050056) was filed on 13 Jan 2015 and this has been followed by national filings at the US and European patent offices.

Copyright exists in the hardware design drawings, the control software and documentation.

 

Patent Information:
For Information, Contact:
Ceri Mathews
IP & Licensing Manager
King's College London
ceri.mathews@kcl.ac.uk
Inventors:
Trevor Coward
Jim Smay
Swati Jindal
Mark Waters
Keywords: