PESU replaces PEI in highly durable sensors for healthcare applications

• Liquid analytic sensors seal sensitive electronics
• Good flowability permits design of thinner walls and more complex shapes
• Continuous use temperature up to 204°C (399°F)

A new healthcare-grade polyethersulfone (PESU) from Solvay Specialty Polymers is now being used by Advanced Sensor Technologies Inc. (ASTi) to produce extremely durable sensor products for medical and biopharma applications. ASTi is an industry-leading designer of laboratory, medical and industrial electrochemical sensors.

Liquid analytic sensors seal sensitive electronics

Available in a range of sizes, ASTi’s new liquid analytic sensors seal sensitive electronics safely inside an internal plastic sleeve that is fitted within an outer sleeve – also made of plastic – which houses the electrochemical sensor components. ASTi evaluated Veradel HC A-301 PESU in molding trials to form inner sleeve components where it found the material helped address moldability, cost and thermal cycling issues posed by an incumbent polyetherimide (PEI) grade.

“Solvay’s high-flow polymer delivers more cost-effective processing options, improved mechanical performance and higher transparency than the PEI grade we had previously used,” said Martin Patko, president and founder at ASTi.

Good flowability permits design of thinner walls and more complex shapes

ASTi found Solvay’s comparatively high flow PESU enables the design of family molds that produce very little waste, and allows molding of selective parts with flip gates. The material’s good flowability also permitted the design of thinner walls, more complex shapes and different cross sections within finished parts. Its high transparency further facilitated final assembly of integrated parts.

Continuous use temperature up to 204°C (399°F)

ASTi engineers prefer bound and press-fitted parts vs. less reliable washers and O-rings to seal the sensors. Consequently, the comparatively similar thermal expansion rates between Veradel HC A-301 PESU and the polymer specified for the outer sleeve of the sensor also helped minimize strain on these critical seals during thermal cycling. Solvay’s PESU grade offers a continuous use temperature up to 204°C (399°F), which can potentially contribute to more durable sensors and components.

The Veradel HC PESU grade has been tested under ISO 10993 biocompatibility standards for cytotoxicity, irritation and acute systemic toxicity. It is the first PESU polymer for use in medical devices to offer a Master Access File (MAF) on record with the U.S. Food and Drug Administration (FDA), according to the company.