Chapter excerpt from the ebook MedTech IP: Lessons and Strategies for Success - view all chapters here.
3D printing is now widely used in a variety of MedTech areas, for example in the manufacture of custom-fit artificial limbs (prostheses), external supporting devices (orthoses) and implants for operations and dental procedures. Additive manufacturing (a more general term, which includes 3D printing) also allows the production of customised drugs by printing a patient-specific mix of drugs into a single pill.
There are a number of special considerations to take into account when patenting inventions relating to additive manufacturing / 3D printing.
First, it is important to realise that almost all products can, at least in principle, now be produced by 3D printing technologies, and this allows interconnecting parts to be produced with structures which were not previously practical or possible. Such structures must be foreseen when drafting patent claims to ensure that they fall within the scope of the claims.
Secondly, 3D printing uses computer files which may be copied and transmitted quite separately from the products themselves. For this reason, when patenting inventions relating to 3D printing it is important to include claims which protect these files, and/or which will be infringed if such files are used.
Computer simulations are often used when designing medical items to be 3D printed. In 2021 there was a significant change in the law when the Enlarged Board of Appeal of the European Patent Office decision G1/19 relating to computer simulations. Under the new law, claims to simulations must in effect specify what practical use is made of the simulation, and such practical uses must also be given in the description of the patent specification.
Let's take a look at an example of a patent for a personalised heart stent, which was made possible by the work of a remarkable young engineer in 1983...
In 1983 Chuck Hull, a young American engineer, called his wife from a small laboratory late one night. There was something he wanted her to see. Could it not wait until the morning? She was in her pyjamas, after all. No, it could not wait. He asked her to get dressed, and come to the laboratory straightaway.
What was so important that it could not wait until tomorrow?
Chuck had been working at a company called Ultraviolet Products, which worked with UV-curable materials used for coatings for furniture, such as tabletops. After the material was applied, UV light was used to harden the coating. Chuck realised that it might be possible to cure multiple layers of such a material in order to produce a plastic object. In a small laboratory, he started playing around at evenings and weekends to see what he could produce.
He used photopolymers, which are typically acrylic-based materials that are liquid until they are exposed to ultraviolet light, at which point they turn solid. He created a process in which you start with a container filled with liquid photopolymer, and use a computer to draw on the surface of the liquid using a focussed UV light. When the UV beam strikes the surface, the photopolymer changes to a solid, thus producing the first layer of the object. The object is then lowered by a small amount before producing the next layer, and so on, until a whole object has been produced, at which point the object is lifted and emerges out of the liquid.
When he called his wife late one night in 1983 Chuck Hull had at last succeeded in "printing" a 3D object. He wanted his wife to be the first to see it.
Chuck successfully protected his method by means of US Patent 4,575,330, granted in 1986, in which he coined the term “stereolithography” for this process.
Stereolithography, or "SLA" printing, soon became a widely used technique in rapid prototyping and direct manufacturing. Chuck co-founded 3D Systems, and in 1987 his company produced the first ever 3D printer.
Today, Chuck has 93 US and 20 European patents to his name, and in 2014 he was awarded the European Inventor Award in the Non-European countries category by the European Patent Office.
As we shall see, Chuck's method can be used with great efficacy in the MedTech industry.
On 17 February 2015, Siemens Healthcare GmbH filed European Patent Application No. 15714009.6 relating to a personalised heart vessel stent which could be produced by 3D printing methods, including stereolithography.
In Chapter 5, about AI and MedTech, we looked at a patented AI system which is capable of detecting reduced blood flow to the heart (so-called myocardial infarction). Now we will consider an invention which aims to treat such a condition using 3D printing.
The Siemens application explains:
Cardiovascular diseases (CVDs) have become the prime cause of death around the world. More people die of CVDs than any other cause. ... One of the common ailments in CVDs is the deposition of plaque in cardiovascular arteries. The plaque deposition can block the blood flow in the heart thereby resulting in myocardial ischemia [a lack of blood flow to the heart muscle] or myocardial infarction [commonly known as a "heart attack", caused by cessation of blood flow to the muscular tissue of the heart, known as the myocardium].
One of the most common remedies for CVDs is deploying stents into the arteries where a significant plaque deposit is found. Currently, there are a number of prefabricated stents available in different sizes and shapes which can be inserted in the arteries based on an assessment by a doctor. However, the prefabricated stents cannot be personalized according to the nature of the plaque deposit in the affected vessel of the subject. Recently with the advancement of the additive manufacturing there is scope for manufacturing personalized stents.
Figure 3 of the Siemens patent is shown below. The figure shows a blood vessel 25 containing a region of interest (ROI) 26 containing a calcified plaque region 27, causing a "stenosis", which is a narrowing of the blood vessel 25.
According to the patent application, images of the blood vessel could be produced by suitable scanning technology, such as ultrasound, MRI or computerized tomography, and a model generation module could then generate a personalized multidimensional model of a suitable vessel stent for the patient. In particular, the design and composition of the personalised vessel stent could be such that the stent exerts minimal pressure on the calcified region 27.
An example of such a personalised stent 28 is shown in Figure 4 of the patent, shown below.
As can be seen from the figure above, the stent 28 is designed to hold the blood vessel 25 open, while at the same time curving around the calcified region 27, so as to reduce pressure on this region.
Siemens were successful in obtaining a granted patent for a method and device for customising the vessel stent, with the method taking into account, "a length, a thickness, a composition, a level of calcification and a distribution of a plaque deposition at the stenosed region; the personalized vessel stent (28) being composed of a plurality of materials so as to exert minimal pressure on the calcified region (27)."
The Siemens application discussed above also described a module configured to simulate inflation of the personalized vessel stent within the coronary vessel of the patient. The simulation could be used for verifying the inflation of the personalized vessel stent under different pressure values of an inflating balloon, and to verify the fit of the stent with respect to the stenosed (i.e. narrowed) region of the vessel. In case the stent design did not appear to fit well in the simulation, the design of the stent could be remodelled for a better fit.
Computer simulations of this sort are used in a variety of MedTech technologies, so it is worth taking a moment to consider the patent position in relation to such simulations.
In 2021 in Europe there was a significant change in the law when the Enlarged Board of Appeal of the European Patent Office (EPO) issued its decision G1/19 relating to computer simulations. Before this decision a leading earlier case (T1227/05, which related to the simulation of a circuit subject to 1/f noise) held that simulation of a technical system was sufficient to establish a technical purpose. Under the new law claims to simulations must in effect specify what practical use is made of the simulation, and such practical uses must also be given in the description of the patent specification.
Of course, in MedTech inventions of the type we have been discussing there is an obvious practical application in the form of improving the fit of the personalised item to the patient. Therefore, provided such simulations are limited to these or other practical applications, the simulations should be patentable at the EPO, provided other requirements such as novelty and inventive step are met. In addition, the resulting products (in this case the personalised heart vessel stents) would also be patentable in themselves, again provided that the requirements of novelty and inventive step are met.
We should be thankful for pioneers like Chuck Hull.
