Testing is critical to product development. But it becomes even more important when customer lives depend on those products. For example, angioplasty equipment must be tested not only to satisfy federal regulations, but also to ensure patient safety.

Accurately testing many medical devices depends on sealing parts of those devices during test procedures, a task that poses several challenges that can be met by pneumatically activated seals.

Angioplasty balloons, for example, must be inspected for defects, so they are inflated typically from 6 to 20 atm, and inspected for defects. Manufacturers recommend testing angioplasty balloons only once, since retesting reduces the balloon's elasticity and could lead to a failure while being used. Should there be an error during testing, second tests are discouraged but allowed, and third tests are prohibited. Effective, one-time testing depends on ensuring a leak-free connection between the catheter used to insert the balloon into a patient's artery and the test device.

Sealing the catheter during testing also means no contaminants can enter the balloon because they can invalidate tests and potentially let defective balloons pass muster. Traditionally, companies hand-threaded test devices onto the catheter's luer fitting. This labor-intensive method is not well-suited to high-volume manufacturing, and can damage the manifolds, which have the structural integrity and durability of angel hair pasta.

Testing syringes and other drug delivery devices also presents challenges. To keep patients comfortable and as pain-free as possible, syringes have become smaller and use micro-thin needles. But this means parts are more delicate and more easily damaged during testing. And needles as small as .015-in. in diameter are too small to seal using traditional hand-applied connectors.

Another common problem as more firms add inspection to assembly lines is that seals either cannot withstand the speeds and feeds common in today's manufacturing plants, or they damage products. And testing product integrity with high-pressure air or liquid doesn't work because traditional seals cannot withstand the pressures.

Pneumatically actuated connectors

Pneumatically actuated connectors solve many of the problems encountered when leak testing medical devices. Pilot pressure used to activate connectors can also control sealing and gripping forces. The connectors can also be designed to control force so as not to overstress delicate devices or test equipment.

The connectors work with most leak testers, and can be used regardless of test media: nitrogen, helium, or hydrogen. When helium is used, for example, these connectors establish seals that leak only E-6 cc/sec (or 0.000001 cc/sec) and can operate in pressures ranging from hard vacuum to over 33 atm, so they can accommodate a broad range of test procedures.

To prevent devices from being damaged while testing, connectors can act as fixtures and grippers. For example, a pneumatic clamp on a connector can hold the device being tested against the connector, acting as a “third hand.” The clamp would let the connector grip and seal either an inside or outside diameter. Users can control the clamp by activating it with the connector's pilot pressure, the same pressure that lets the seal grip.

Connectors can also be equipped with a higher quality seals which are softer than the poured-urethane rings normally used in connectors. This “soft touch,” establishes a seal without creating occlusions, and when it fails, it fractures, unlike urethane seals that break down slowly, letting slivers of urethane contaminant the product and the test.

Equipping pneumatic connectors with a media port lets users purge solvents or particles left over from manufacturing or shipping by sending air or a liquid through it.

Connectors can have an interchangeable extended and reduced front housing for the flexibility to test a variety of micro needles (0.015-in. in diameter). The front housing holds the device in place for testing.

Pneumatically sealing connectors can also be used in other manufacturing and filling and flushing applications. For example, if glass tubes must be inspected quickly (less than 1 sec per test), robots can engage and disengage the connectors. The relatively lightweight connectors are excellent end effectors that need relatively small robotic actuators, which might let some companies replace larger robots and save factory floor space. Devices could even be tested while being moved by robotics.

Connectors' soft-touch grips that holds flexible and delicate parts during testing can also hold them during assembly. For example, some devices such as a lumens and endoscopes must be held while a pull test verifies they are securely assembled.

There are several caveats when using sealing connectors for testing. Parts that flex or bend can lessen the seal strength. This loss of grip can result from lost pilot pressure or because the part has residual liquid or powder from the manufacturing process.

Pneumatically actuated sealing connectors can help ensure patients get quality, economical devices. They can be used in high-volume settings to eliminate much of the manual labor associated with sealing and gripping devices, as well as prevent product damage. Most importantly, these connectors ensure tests are done correctly.