TECHNOLOGY NEWS - QUALITY CONTROL
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The 700G leak detector can determine the integrity of fully assembled medical devices with the sensitivity of 3.0 × 10–13 atm-cm3/sec.
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A new system can detect a leak as small as 3.0 × 10–13 atm-cm3/ sec—a leak so small that it would take roughly 2 billion years for a tire holding 20,000 cm3 of air at 2 bar to lose half its volume. The leak detector from Pernicka (Fort Collins, CO, USA) is the first to determine hermeticity by means of a process known as cumulative helium leak detection (CHLD).
Suited for assessing the integrity of packaging and fully assembled medical devices, CHLD technology can perform gross-leak tests on products such as insulin pumps without the use of CFCs. Insulin pumps contain a pressurized gas chamber that is traditionally subjected to separate gross- and fine-leak tests before assembly. By contrast, “CHLD allows testing of the final, ready-to-ship product with one test,” explains Pernicka vice president Bill Burkard.
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Assessing hermeticity with accuracy that is orders of magnitude greater than other technologies has already gotten the attention of suppliers to NASA and US FDA–regulated industry, who are using the technique to test satellite components and implantable medical devices, respectively. “We think the medical community will be very interested in the CHLD tester,” says Pernicka spokesperson George Grenley. “The cost of the test is minimal, and it is possible to safely test a component with great accuracy, and to do so repeatedly, if needed.”
Pernicka’s method exposes a product or package to pressurized helium, whose small molecules will penetrate even minute leaks. The test chamber is then purged with pure nitrogen, and a cryopump reduces the pressure and freezes any gases heavier than helium. At this point, the pressure in the system is analyzed. If no gross leak is present, a mass spectrometer determines if the part has any fine leaks.
“The unique innovation of the leak tester is that it is a closed system,” explains John Pernicka, the company’s president and inventor of the machine. “Because the system accumulates and analyzes all gases in the system, [it can] detect extremely small, slow leaks that might not show up in service for months or years.” Pernicka’s CHLD method can help medtech manufacturers provide implantable devices that last at least as long as the patients who need them.
