3D Printing Medical Devices

3D printing is often touted as a big advance that will quickly change our lives.  Medical Design looked at the technology and I thought I’d look at how 3D printing can now affect medical device development and manufacture.

According to Wikipedia, 3D printing is a process of making three dimensional solid objects from a digital model. 3D printing is achieved using additive processes, where an object is created by laying down successive layers of material. 3D printing is different from typical machining which remove material by methods such as cutting and drilling.

I’ll look at three categories, prototyping, manufacture, and other uses.

Prototyping

3D printing looks promising for prototyping with additional materials and maybe a price advantage over SLA.  A cheap injection mold is $10k for one part, 3D printing can make that for part $5.  A 3D printer is certainly a good tool to get physicians and executive types interested.  However, the use of prototypes are limited in the medical device field due to material limitations.

Medical Device Manufacture

At this point, medical device manufacture or even component manufacture with 3D printers seems unlikely until a great deal more development is done for the following reasons:

Multiple materials

 3D printers have difficulties with multiple materials.  You can construct scaffolding and use the 3D printing around it to create a device.  Single material medical devices are usually high volume, molded, packaged, sterilized and sold, (i.e. fittings, tubing, etc.) this doesn’t play to the strengths of 3D printers.

Biocompatibility / Sterilization

Additionally, I’m going to assume that the materials need to be biocompatible and sterilizable.  A look at Shapeways’ material portfolio at this time doesn’t show a lot of promise for medical device applications.

The materials are Alumide, an acrylic plastic, stainless steel, sterling silver, full color sandstone, and ceramics.  Only the ceramics material is listed as food safe.  Starting with a material that is not food safe is a stretch, but let look at some of the materials in more detail.

The stainless steel is alloyed with brass and uses small drops of glue to hold the material together and the material itself is specifically listed as not food safe (the glue is not described).  Alumide is described as nylon plastic filled with aluminum dust, the material is described as not watertight and not food safe.  The silver is a two step mold, so it may be pure silver, silver isn’t really used a lot in medical devices, but there may be some applications.  The ceramics material is food safe and watertight; ceramics are used in some implant devices, but the page says sharp edges are likely to crack, so that limits the applications.  You don’t want any material in your body that is named “sandstone”, so I’ll move on.  3DSystems does offer VisiJet Crystal, another UV curable acrylic plastic, which is USP Class VI certified, so that is probably the most promising material.

Resolution

Looking at the aforementioned Shapeways material portfolio using their strong and flexible plastics, the minimum unsupported wall is 0.7mm, with +/- 0.15mm accuracy this type of resolution removes just about every vascular application you can think of.  That leaves large implants and custom surgical tools as the most promising areas at this point. 

Shapeways seems to be more consumer oriented, so lets look at another company.  3DSystems does claim a resolution of 0.075mm with 0.050mm layers.  However, this needs to be combined with the material to give us its real capabilities.  To be fair, I’ve only looked at the capabilities from a couple companies.

Current Activity

Wikipedia describes how 3D printing can produce a personalized hip replacement in one pass at available printing resolutions the unit does not require polishing, but gives no source.

EOS and IMDS have teamed up to explore custom implants.  Stryker is building knee implants.  Others are apparently making WREX arms.

There is a lot of talk about how 3D printing could improve current devices, and hip implants are frequently cited as a promising area, but few specifics or even record of people working on the technology.

Other

Replacement parts are sometimes mentioned as a use for 3D printed parts, but again, this seems unlikely for the same reasons you can’t currently make components.  You could make the same argument for 3^rd world countries or as a way around regulations (i.e. a physician making herself a device), but you run into the same problem.  So what other applications related to medical devices are there?

UCSD is using 3D printers to print blood vessels.  This seems interesting, in-vitro test models are often expensive and sometimes you want to destroy them during testing, but you can’t.  You could presumably expand this idea to all kinds of models and validate your device on many more anatomy types than previously.

Conclusion

Right now 3D printing is too new to find many applications in medical devices.  Aside from prototyping, the uses of 3D printing in the medical device field are limited, most medical device companies already prototype using SLA, so this will not be a big improvement.  The medical device industry is often 10 years behind the consumer industry, unless the idea is an excellent fit or custom developed for medical devices, since there are very few consumer applications for 3D printing at this time it is probably better to wait until the 3D printing industry is more mature.