MEDICAL | INNOVATION


Celanese says LCP (Vectra MT) scores over PC with its high flow, important for thin-wall parts (LCP tested was glass reinforced, PC was unfilled). Test part devised by Celanese Source: Celanese


inertness and processability. “The need to create solutions to support rapid


Covid-19 diagnostics came with urgency and was combined with the continuous request for miniaturi- sation and material processability improvements – all factors that boost innovation and development,” says Polyplastics. “Customers that were already developing and manufacturing microfluidic devices accelerated their timelines and other companies pivoted to develop their own versions.” Big corpo- rations and start-ups alike sought ways to satisfy the unforeseen surge in demand.


Many new developments involved submicron


features with incredibly fine detail to be replicated. According to the company, the high dimensional stability of TopasCOC ensured products consist- ently performed as designed. Microfluidic devices have thin wall geometries


and large aspect ratios, which presents a challenge for high-output injection moulding. Materials need to have high flow with a wide processing window. “Topas COC offers a great combination of both,” says the supplier. Grades are available that provide melt flow high enough to replicate thousands of microchannels in a plate 2x4 inches (approximately 50x100 mm) while using a repeatable and stable moulding process. “Even with the recent advances in design,


materials, and processing, there is so much to improve and innovate,” says Polyplastics. “Every step of the process is being challenged. Efforts are underway to examine each injection moulding parameter, eliminate the use of adhesives, reduce manufacturing waste, and develop polymers that enable the technology with the least amount of material.” “Those associated with the drug delivery supply chain understand the sheer volume of complex and interconnected considerations that need to be


58 INJECTION WORLD | September 2022


made at each stage of the lifecycle, from bench to market and through lifecycle management.” So says Wim Vos, Principal Field Development Engineer within the Medical Group at Celanese. “They are also acutely aware of the implications of those decisions, especially when it comes to patient health,” he says. “Whether representing design houses, device developers, CDMOs [Contract Development and Manufacturing Organisations] or pharma partner, teams must solve a tricky formula encompassing matters of cost, risk, time to market and safety, both from a manufacturing and regulatory standpoint.” One key element in planning for success with medical devices is the choice of polymer, particu- larly for the manufacture of small or intricate parts, says Vos. “Miniaturisation is a notable current trend that presents many opportunities. However, the smaller the part, the bigger the challenge can be in terms of consistency, quality and efficiency.” Vos says Celanese supports its partners through this critical phase by leveraging a comprehensive and customisable portfolio of technical services all the way from laboratory testing to optimising material selection and supporting manufacturing scale up. Through a mix of internal developments and acquisitions, the company now has one of the broadest portfolios of materials for medical applications of any polymer and compound producer in the world. Comparisons made by Celanese were made with standard solutions commonly used in injection moulding, often selected for the low price of the material. “However, when moving from low volume test production to production at scale, those materials have significant disadvantages in terms of ‘hidden’ costs attached to efficiency, throughput, and quality,” Vos says. In considering the implications of correct polymer choice for injection devices, one compari- son he makes is between liquid crystal plastic (LCP) which Celanese produces under the Vectra and Zenite banners, and a rival polymer, polycarbonate. LCPs are already used in electronics components, where tight tolerance designs with high levels of stiffness and strength are paramount. They enable production of parts with extremely thin walls (as little as 0.2mm) with no flash. Exceptionally high flow and low heat of fusion result in very fast cycle times. “While filled polycarbonate also enables the low friction [needed for] easy actuation of injectable devices, it has limited ability to mould detailed, thin-walled parts and also requires longer cycle times,” says Vos. “LCP has much higher modulus than PC. To get PC in the same range requires glass


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