The PPI (Precision Pen Injector), an award-winning, next-generation injector from Scandinavian Health Ltd (SHL) uses key components made of DuPont Delrin acetal resin. This material was selected for its strength, stiffness and low wear/low friction performance. The Precision Pen Injector (PPI) is designed to deliver small doses of Restylane Vital Light, a treatment for rejuvenating delicate skin, produced by Swedish biomedical firm Q-Med AB. Since its launch in January 2009, the PPI has received praise from doctors and clinicians alike for its ease-of-use and compact design. Furthermore, the PPI was recently recognised with the prestigious red dot award for product design.
This ergonomic, compact and intuitive device replaces traditional syringes where desired accuracy may be difficult to achieve. Preloaded with Restylane Vital Light, one PPI can quickly and precisely deliver 200 doses with outstanding accuracy. Such precision is achieved by using a patented pressure release mechanism to pump out one exact 10 µl droplet through the needle into the injection site.
Due to the high precision required for this product, and the constant high force requirements needed for a highly viscous solution, SHL design engineers turned to Delrin for many of the device’s key components. This engineering thermoplastic was chosen for its strength, stiffness, and high dimensional stability. The natural lubricity of Delrin for reduced levels of friction between interacting parts helped to facilitate a controlled yet faster injection process.
An enhanced-performance grade of Delrin, a medium viscosity acetal homopolymer with glass fiber reinforcement, was selected for the wind knob and button of the device for its low warpage and good creep resistance. Delrin resins, offering improved processing thermal stability, were used for many of the drive mechanism components. For other components within the PPI, the spring-like properties of Delrin were crucial to secure the reliable closure of the syringe following the injection procedure.
“By using high performance materials such as Delrin for the device, we have delivered a product that is far more accurate and efficient than anything else currently on the market,” said Stefan Högdahl, Design Engineer for SHL Medical. He further commented saying, “This device features unprecedented repeatability for a system that can consistently and accurately produce extremely short plunger movements with extremely small displacement variation.”
Recognition of the injector pen’s innovative design came in the form of a prestigious red dot award for product design in March 2009. With an eye on further enhancing the performance of future generations of similarly high-performance products, SHL is currently assessing the use of DuPont Crastin PBT polyester resin for components involved in drive units of a similar nature. The adoption of Crastin can potentially further reduce friction and enhance the performance of the system, particularly when interacting together with parts made of Delrin.
