ENGINEERING INSIGHT
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Thermoplastic elastomers used in biopsy valves add ozone resistance and UV stability.
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Used in standard endoscopic procedures, biopsy valves designed for limited reuse must be cleaned and disinfected or sterilized prior to each use. According to medical personnel, however, the traditional silicone valves can be difficult to clean. To address this concern, US Endoscopy (Mentor, OH, USA), which specializes in the design and manufacture of gastrointestinal endoscopy products, set out to source an alternative material. A thermoplastic elastomer (TPE) formulation from GLS Corp. (McHenry, IL, USA) made the (medical) grade.
Biopsy valves are designed with seals to squeeze off blood and body fluids as the sample is withdrawn from the biopsy channel. Remaining biomaterials can collect within the internal nooks, crannies, and crevices of a valve. Because of the valves’ complex design, these biomaterials cannot be removed with a standard cleaning brush. This can result in areas that harbour dangerous pathogens. Furthermore, reprocessed silicone biopsy valves can stretch and leak.
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A biopsy valve is used in endoscopy equipment to reduce leaking of potentially infectious biomaterials.
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Safe Harbour
BioShield endoscopic biopsy valves from US Endoscopy are designed to protect patients from exposure to contamination caused by product reuse. The TPE material, coupled with the valve construction and an airtight design, reduces the component’s hissing and leaking of potentially infectious body fluids onto healthcare personnel.
“Our market research indicated that many users were dissatisfied with the performance of silicone valves with respect to leakage,” says Christopher Kaye, manager of advanced engineering and polymer technology at US Endoscopy. “There was also some question as to whether the valves were being adequately cleaned.”
As a result, the firm opted to find a silicone substitute and worked to establish numerous performance standards. According to Kaye, the new material had to:
• Run easily on the firm’s injection moulding presses and in its multicavity moulds.
• Impart a tight seal.
• Be versatile enough to meet the product’s design parameters, notably the softness and hardness necessary to achieve a proper cap-to-body fit and eliminate any potential for leaks.
• Enable a tube to be bonded to the body material for units sold with irrigation tubes.
• Provide a controlled degree of tackiness for the valves to remain affixed to endoscopes.
• Be user-friendly for medical professionals while safeguarding patient safety.
• Possess good colourability to differentiate the products from other valves on the market.
“After discussing our needs with several TPE formulators, GLS was able to provide the most suitable grade to ensure US FDA compliance,” says Kaye. “We achieved what we needed—ease of processing, a rubbery feel, a soft touch, and excellent colourability.” The TPE not only has the desired performance characteristics, but it also has good ozone resistance and UV stability.
US Endoscopy has used TPEs in other product applications. For example, a TPE from GLS Corp. was used to fabricate a seal on the firm’s Guardus overtube line, which is used for removing foreign bodies or impacted food from a patient’s oesophagus.
To learn more about GLS Corp., select #7 on the reader service card or go to RequestLink at www.devicelink.com/emdm.
