Medical resins come together in surgical pencil

A Sabic Innovative Plastics product story

Edited by the Engineeringtalk editorial team Jul 19, 2006

Noryl and Ultem resins are used in the new 12-use E-Z Pen electrosurgical pencil from Megadyne Medical Products.

GE Plastics' Noryl and Ultem resin grades were chosen for the new 12-use E-Z Pen electrosurgical pencil from Megadyne Medical Products.

Lightweight and ergonomically designed with both 10- and 15-foot, kink-resistant cords for easier, more comfortable handling, E-Z Pen pencils are the only product on the market offering patented E-Z Clean nonstick tips that allow surgeons to make cleaner cuts.

The versatility and variety of GE's portfolio of materials for medical device applications, combined with GE value-added services such as colour-matching, enabled Megadyne to meet the specific requirements of this application.

One of the noteworthy features of the E-Z Pen is its patented lockout mechanism that is automatic with sterilisation.

This mechanism, located inside the electrical connector, clicks a gear each time the unit is sterilised.

After 12 uses, the lockout plunger fully extends to prevent further use of the connector and avoid a potential safety hazard.

It does not require the user to track how many times the pencil has been used.

This prevents possible injury to the clinician or patient by locking out the pencil from use before materials degrade to a dangerous or unvalidated level.

"We created the 12-use E-Z Pen to provide hospitals and surgical centres with a cost-effective, reusable tool for electrosurgery incorporating a unique safety feature that prevents additional use after the lifespan has expired", said Michael Hintze, Vice President of Marketing for Megadyne.

"The components of this device required a variety of different materials that could provide very specific properties".

"We turned to GE Plastics because they lead the industry in breadth and depth of products for the medical device sector, and offer a number of invaluable services".

"GE's materials helped us bring this high-performance, safe, and effective new E-Z pen to market".

With exceptional resistance to autoclave temperatures as high as 134C, the GE resins delivered high mechanical performance and excellent retention of physical properties after repeated sterilisation.

The resins also contributed to the design of a less bulky and lighter weight Megadyne E-Z Pen.

The following GE materials are used in the E-Z Pen.

GE's Noryl resin was selected to mould the pen housing and the patented lock-out plunger.

The most important property of this resin was its ability to maintain structural integrity during repeated autoclave cycles.

The custom colour of the Noryl resin grade was created by GE's colorXpress service, a speed, industry leading comprehensive colour selection and development service.

Two grades of GE's Ultem polyetherimide (PEI) resins were chosen.

A glass fibre-reinforced grade of Ultem resin was used to mould the green electrical connector, whose internal features have tight tolerances.

The autoclavability of this grade was critical, especially because many of the internal components of the plug are under load and can move when exposed to the high temperatures of the autoclave.

Plug functionality is critical to proper operation of the device, and this material was unfailing in this application.

GE's unfilled Ultem resin was used to create the see-through, yellow-tinted window on the electrical connector that provides a readout of how many uses remain for the E-Z Pen.

In addition to autoclavability, this grade offered high clarity as well as excellent chemical resistance and high dielectric strength.

GE's Ultem resins are widely used in medical and chemical instrumentation, due to their resistance to chemicals and heat, and good dimensional stability.

Equally as important as its materials, GE provided several services to enable resin selection, colour- matching, and process optimisation.

According to Darcy Greep, E-Z Pen Project Engineer at Megadyne: "GE helped our moulder to overcome some process issues very rapidly".

"And their colorXpress colour-match service was awesome".

"GE's response time to critical deadlines was fantastic and their ability to precisely match to our colour was excellent".

Clare Frissora, Market Director for Healthcare at GE Plastics said: "This application is a great illustration of how GE's broad scope of materials and range of services facilitates the application development process for designers and device manufacturers".

"Instead of going from one manufacturer to another for specific material properties, Megadyne was able to find the right resins for three very different components - including custom colouring - from one source".

"GE Plastics' extensive materials portfolio and industry-leading expertise enable manufacturers to save time and effort in designing new products".