Single life – advancements in novel polymers

Something of a sea change has taken place on the materials side of the medical device industry in recent years. The move from metals to plastics has gathered seemingly unstoppable momentum as the lower costs, light weight and better biocompatibility convince growing numbers of manufacturers that plastics are the future. Global demand for medical polymers was around five million tons in 2013, and this figure is predicted to grow to more than seven million tons by 2020, according to a report by Grand View Research.

This increase in demand has put great pressure on materials developers to keep coming up with new polymers of greater durability and versatility at the most competitive possible cost. This is made harder by things like hospital-acquired infections - or more specifically, the damage the disinfectants being used to fight them have been shown to do to plastics that have inadequate chemical resistance.

At the same time, there is growing clamour from medical practitioners and the public for a more sustainable approach to medical device manufacturing. This will involve the use of more bioabsorbable materials and single-use tools, which may not necessarily be environmentally friendly.

One player at the heart of this research is Belgian-based chemicals company Solvay. Its healthcare team sits within the speciality polymers business, which employs around 2,000 people and produces 35 brands of polymer. Its healthcare portfolio is smaller - due to higher barriers to acceptance, such as biocompatibility requirements - consisting of seven polymers for medical-grade plastics and four for implantable uses.

Recently, it unveiled a new polymer for medical use, Veradel, defined by its stiffness, heat resistance and high flow rate, making it well suited to thin-walled parts and those with complex geometries, such as internal components of diagnostic equipment. Dr Jeff Hrivnak, global business development manager for healthcare at Solvay Specialty Polymers, spoke to us about Veradel, efforts to create a more sustainable business and what will need to happen before single-use instruments become common place.

Medical Device Developments: Tell us about the development of Veradel. Which qualities were you trying to achieve in developing the polymer?

Dr Jeff Hrivnak: It was a little different to the normal process. Veradel had been around for a while, just not in the healthcare portfolio. It's currently used in the foodservice market and also the water membrane market. There are some forces being seen in the market for PI [polymide - a polymer made up of imide monomers] materials; there's a shortage out there, and the timing was right to bring Veradel into the healthcare portfolio.

But to do that, we needed to do some work: we needed to do our ISO 10993 biocompatibility testing for cytotoxicity, systematic toxicity - those kinds of things. The other thing that we did, which we believe is a first, was to develop a master access file to help bring it to market. The file has all the data that our customers need to take to US FDA for approval.

What medical uses is Veradel most suited to?

Biopharma, for sure. We have a customer that just used Veradel for a sensor. This company was in the industrial sensor business, trying to measure different ions. It is now moving into the medical space - if you think about your blood, you have all different types of electrolytes and ions, and their technology fits very nicely with this. What they liked about Veradel is that it's very clear, you can sterilise it and it also has extremely good flowability, so it gives you the ability to try to make these complex parts, these tiny sensors.

What industry trends are shaping the research you are doing when it comes to polymers?

Hospital-acquired infections are still extremely relevant. We have a pyramid that shows all the different levels and grades of plastics, and the materials we use sit at the top of that pyramid. These materials can withstand the chemicals being used in the medical industry. The trend is going to be for more of this sterilisation, and plastics like this being considered for different types of housing and pieces of equipment.

The other trend with hospital-acquired infections is the idea of a single-use instrument. With single use instruments, you don't have to go and get them sterilised - you just use them once in an operation and then throw them away. Materials like the ones we work on are very popular for single-use instruments, and the trend is definitely starting to go in that direction.

Does the use of these instruments go against the broader trend towards greater sustainability? It seems on the surface to be more wasteful.

We've recently completed a life-cycle analysis of that to try to understand the subject a little better. If you're just throwing the instrument away, some surgeons asked us, is it green? Because of this, we started to look at metal instruments versus plastic instruments, and we did an analysis of the footprint. A lot of the time, these instruments are transported from hospital to hospital, as they may be used to carry out different operations or the sterilisation may take place off site.

We did an analysis looking at the US, Europe and Australia, and came to the conclusion that it depends on how far away you are and that transportation costs are a very strong driver in this. Overall, it was more or less neutral. In some cases, single-use instruments even came out ahead because of the water and energy costs associated with the sterilisation, and then the transportation on top of that. So I think we are going to see a trend towards that in the future.

Are the polymers with the right characteristics for single-use instruments already in the market or will a lot of R&D be required?
These materials are already in place; it's really all about the medical device manufacturers. Just because you have
a metal retractor, for example, it doesn't mean that you can just design a plastic retractor that looks exactly the same. If your engineer is used to dealing with metal and they just try to copy it exactly, it's probably not going to work. But if you take a plastic model and you strengthen some of the different parts of it, you can make it lighter and make the grip more comfortable for the surgeon.

We did this as a proof-of-concept demonstration with a hip retractor; when you have to pop a hip out, you use the retractor to hold it back. We designed one out of these materials, and showed that it can work in plastic [Solvay used Ixef polyarylamide resin for a single-use version and AvaSpire polyaryletherketone for a reusable version]. So I think medical device engineers need to move over into the plastics space and try to understand how plastics can give them a lot more design freedom. If you're used to using metal, then that is all you're thinking, but if you start to open up your thinking, then it gives you a lot more opportunities.

Is the material change, from metal to plastic, inevitable or are some device manufacturers insistent on sticking with what they know?

Yes, it's inevitable, and we are starting to see it as well for instruments on the orthopaedic side. So if you are designing a new hip, knee or shoulder, if you're one of the big OEMs, there are instruments that go along with that. The trend is that surgeons want less-invasive surgery, as they want patients to recover as quickly as possible. Plastics are enabling OEMs to design their equipment in different ways so surgeons can have fewer pieces of equipment and don't have to take 25 trays of tools into the operation; you can have fewer trays of tools going in, and you can design them in different ways to try to maybe simplify the operation or have tools do multiple things.

Also, you have the weight to consider. If you hold some of these instruments, they are heavy, and the surgeons would really like to have something that is not so heavy and a little more ergonomic.

What has to happen before single-use instruments become commonly used in hospitals?

The single-use trend has been coming for a while, and I feel like it is reaching critical mass. The material was brought on to the market maybe seven years ago. We were just at the MedTech show, and we saw several companies coming forward with single-use instruments, so it's really starting to gain some momentum.

Now it's a case of looking at insurance companies and also hospitals, trying to understand how this fits into the whole business model - how it can save money for the insurance companies, for the hospitals, and also that it's something that surgeons want. I think that's probably the next stage of the process.

With a lot of the OEMs right now, if you are using metal instruments to put in a new knee, for example, the instruments just come along with the knee and, in some cases, you're not even paying for them. At the moment, the single-use instrument looks to be an additional cost when it's really not; it just appears that way because that's how current billing practices are. So people need to investigate that a little bit more and see how it can be worked out.