Medical Plastics — Engineered for Precision

Medical Plastics — Engineered for Precision

by Chandrashekhar Modi
Modern Plastics & Polymers
April 2010

Plastics continue to make inroads in medical device designs and applications. From implants to disposables, plastics offer a wide array of advantages including design flexibility, impact, strength, biocompatibility, and the ability to be formed into many different shapes using a wide variety of processing methods. The continued desire to replace metal and glass also provides plastics considerable opportunities. With polymers now being tailor-made, Chandrashekhar Modi delves deeper into the advancements in plastics for medical applications.

Advanced technology, novel materials and new concerns have transformed the healthcare scenario across the globe, inspiring new standards in plastics for medical devices. Designed to restore active healthy lifestyles and quality of life, the use of plastics is gaining prominence in medical devices and equipment. Manufacturers too are continually engaged in developing breakthrough materials, and novel product designs, and line extensions. Consequently, over the next decade, innovations in medical plastics will fundamentally transform the healthcare and delivery subsystems. Further, the ability of plastics to reduce cost allows disposables to replace devices that were previously cleaned, sterilized and reused.

Plastics that find applications in the medical field can be categorized into different types of resins that include commodity resins and engineered resins. Technological advancements, improvements in sterilization techniques, and development of innovative products are some of the factors that are expected to propel demand in the long run. Further, increasing use of combination medical devices, changes in medical packaging market, shift towards miniature and portable devices, and biocompatible features of advanced polymers are expected to promote the development of new products, thereby contributing to the overall market growth.

Corroborates Tom O’Brien, product marketing manager – Healthcare SABIC Innovative Plastics, “By using plastics to create high-end healthcare devices, manufacturers can slash system costs and help drive down the overall cost of the product via part consolidation, elimination of secondary operations and accelerated throughput. For example, molded-in colors and effects in plastics eliminates the need for secondary painting and coating. Plastics can also improve the mold flow and mold release properties.”

Multitudinous applications

The use of plastics in the medical field encompasses several distinct markets. “Plastics is used on a large scale in medical devices like disposable syringes, blood bags, continuous positive airway pressure (CPAP) devices, nebulisers, drug delivery devices, digital signal processing hearing aids, glucose monitoring systems, heart valves, contact lenses, in-vitro diagnostic devices and many more. The global market for home healthcare devices is set to grow by more than nine percent by 2012 with the market exceeding $70 billion in 2012,” adds O’Brien.

The medical device sector is growing at a rapid rate within the developed markets of North American and Europe as well as in emerging markets such as India and China. Further, the drive to market simple and effective drug delivery systems is forcing pharmaceutical companies to look for innovated designs and materials know-how from new external partners.

The concept of ‘zero risk’

As plastics are increasingly employed in drug dosage and delivery, emphasis is being placed on innovative plastics design and manufacturing. End-users are searching for the latest technologies at the most competitive prices without compromising on product safety.

“The fundamental issue here is zero risk. From being able to obtain the correct result of a critical diagnosis through to a patient self-injecting drugs on a daily basis there must be no risk. There should not be any risk of wrong diagnosis being given from a blood test, or a risk of patient injury and infection. This is the rationale for designing plastic disposable items within narrow allowances thereby promoting their wide use,” explains Andrew Sargisson, export sales director, Waldorf Technik GmbH & Co KG.

Additionally, as a lot of health care treatments shift from hospital to home, the need for well-designed user-friendly dispensing and diagnostic devices has been even higher.

Overcoming design issues

Designing a plastic medical device requires years of experience and cross-functional expertise in disciplines like extrusion, injection molding, blow molding, rotational molding and thermoforming. One must also have in-depth knowledge of different materials which are used for manufacture of medical devices. Unfortunately, a medical plastic designer is rarely found to be armed with all these skills.

“It is the responsibility of the company to inform all medical plastic designers of the tremendous advances made in core components and system analysis. Designers globally can be freed from many of the constraints they are currently working within by choosing an advanced manufacturing partner earlier in their development processes. The question of failure-proof products has to be addressed via a development process that is concurrent rather than sequential by the way of which all of the risks created by function, material selection and manufacturing process are evaluated and quantified in real time giving support for challenging the design direction with a high level of confidence in correlation with empirical data derived later,” explains Mike Sullivan, managing director Rosti Technical Plastics (India) Pvt Ltd.

Ergonomics

With the expansion of home healthcare, designers are focusing on ergonomics and aesthetics to make devices comfortable and attractive for consumers. “Plastics give device manufacturers greater design freedom than with metal and glass. The ability to mould complex shapes and to consolidate parts are important in creating eye-catching ergonomic designs. Just as the right design makes a device easier and more comfortable to use, particularly when used repetitively, an attractive appearance makes it less intrusive in the home setting,” asserts O’Brien.

Additionally, a combination of durability and lightweight is critical for any medical devices. They need to be easy to lift and transport, yet tough enough to withstand being dropped onto hard floors. Plastics can provide a lighter-weight alternative to metal, especially through thin-wall molding technologies that preserved strength while reducing mass and weight. For example, PC/acrylonitrile butadiene styrene (ABS) resin can be used for housing components due to its excellent impact properties and a high flow for thin-wall molding.

High-performance materials

The wide variety of high-performance plastics available in the market offers different property combinations needed to meet diverse device requirements. One of the most promising areas is the evolution of plastic compounds. “Compounds can deliver exceptionally high performance, including mechanical strength, lubricity, wear resistance, and dimensional stability, to facilitate tight tolerance for device specifications,” explains O’Brien.

In addition to plastics compounds, materials such as polycarbonate (PC)/polyester resin have a good fit in healthcare applications primarily because of their ability to be water-clear or colorable, biocompatible, lipid resistant, gamma sterilizable and maintaining a good balance between chemical resistance and toughness.

Emphasizing on the biocompatibility factor, Chetan Kadu, area sales manager, Engel Machinery Indian Pvt Ltd, says, “It differs on the type of material and its grade selected for its compatibility with bio-materials like blood, skin and other body fluids. The product designer has to study the relevant aspects such as reaction of material with body parts, mold performance, defect rate, shelf-life and product handling before designing the right material.”

Seconds Dr Vinny Sastri, president, Winovia LLC, “Several plastics are inherently biocompatible or can be rendered biocompatible with specific additives. Nevertheless, plastic formulations must undergo test for biocompatibility and conform to the ISO-10993 series of standards. Several sterilization methods can be used depending upon the need and application. Most plastics are compatible with ethylene oxide sterilization. For steam or dry heat sterilization, plastics must be hydrolytically or thermally stable and have heat distortion temperatures above the steam or autoclave sterilization temperatures. Further, plastics must not degrade or discolor when undergoing radiation (gamma or e-beam) sterilization. However, not all plastics are sterilizable by radiation and many of them require the use of additives like free radical scavengers.”

The competitive edge

Very often, the design and manufacturing operations to produce plastics medical devices have to be adjusted and refined on a daily basis in order to satisfy the increasingly strict and highly regulated biomedical requirements in addition to all the other pressures prevalent in this market. The survival of companies catering to plastic medical applications depends strongly on the success of design, manufacturing, and marketing strategies employed by different companies to meet these requirements.

“The key to successfully launching a medical device, that performs well and can be manufactured in high volumes at a low price, is early consultation with key players such as tool makers, material suppliers, automation engineers and machinery suppliers. Design issues can be overcome at an early stage by allowing product development to happen with an eye on future mass manufacturing,” affirms Sargisson.

Cost consideration

Cost is always an important consideration while designing a medical device due to the stringent norms that need to be followed for ensuring total security of the product. The cost structure of producing a medical device can be a complex subject and reflects a number of factors. However a cost-quality trade off is not acceptable in this context as the design integrity and safety can never be compromised when life is at stake.

Asserts Dr Sastri, “Device manufacturers must place priority in designing and producing safe and defective products. They need to be innovative in ensuring that those processes make cost-effective, profitable products while still complying with all applicable regulations.”

Recent advances

There are new technologies that have yet to be taken up by the medical device industry and should be considered with regard to new devices. For instance, the benefits of rapid temperature cycling (RTC) and infrared tool face reheating render flawless plastic component surfaces that deliver considerable benefits with regard to sterilization and reduction in bio-burden.

Observes Dr Sastri, “Breakthroughs in medical device design deal with developing products that are small with thin walls that maintain their mechanical strength, are biocompatible and can dissipate heat effectively due to the electronic interface within them. Rapid injection molding is making some inroads, though micro-molding is definitely one of the processes that continues to grow.”

While commenting on the latest tools in design analysis, Sullivan says, “Among many analysis tools, finite element analysis (FEA) and non-linear structural analysis can be effectively deployed to establish the performance characteristics of a given design with various material combinations. One can apply different frictional coefficients and consider a design’s performance in the context of: temperature gradients, component warp, long-term creep under load and various surface textures. Depending upon the results design rules can be applied for given scenarios to eliminate identified risks.”

©2011 WINOVIA LLC. No reprints without permission.

An insight into the world of medical plastics

The global market for pre-filled syringes is expected to grow by 8.7 percent CAGR during 2006-2016. In 2008, 1.5 billion syringes were sold worldwide.

In United States, catheters, drug delivery and related disposables experienced the fastest growth among the other product groups at 6 percent every year from 2003-2008.

The EU market is the second largest market for medical devices and disposables. It has a market share of 30 percent, which is only second to the US, which has a share of 45 percent of the total world market.

In Romania, during 2002-2006 the production of medical devices and disposables increased by 14 percent because of increased standard of living and international demand.

In Czech Republic, syringes, needles and catheters make the most on-demand hospital supplies which is slowly making a separate market and is being counted as a niche category. In 2007, this category accounted for 8.25 percent share in the total consumption of medical devices and disposals.

In India medical disposable device segment, the domestic production is bound to increase in the coming future, but imported high-end goods will constitute the majority of sales.

Indian is the fourth largest market in Asia Pacific region with regard to healthcare/pharmaceuticals, behind Japan, China and South Korea.

Contract manufacturers specialized in medical products are the major factor behind the growth in demand for medical disposables such as syringes and intravenous devices.

Worldwide, the medical disposable market’s demand for plastics is expected to reach more than $70 billion by 2012, with a combined annual growth rate for injection molded products ranging between 4.5-5 percent between 2006-2011.

Courtesy: A&M Mind Power Solutions