Leak Testing Considerations for Medical Devices

Medical devices are unlike the majority of other mass-produced products. Blood filters, catheters, syringes, ventilator tubes and other devices must meet strict FDA criteria to be put into market and sold. These medical devices require much more stringent assembly practices than automotive, plastic or consumer products due to their critical nature.They must be properly and accurately tested to ensure high quality. Many medical devices go through a long and arduous premarket approval and validation process to make sure they are safe for use. 

Medical device manufacturers also face many market challenges that can prevent them from fully capitalizing on their product. Some of these pain points include blistering demand crossed with cost-sensitive inflation concerns, increasing regulatory scrutiny underlined by consumer transparency expectations, and raw material supply constraints. Automation is a reliable solution to handle these market challenges.

Comparing Medical and Other Manufacturing Industries

Similar to other manufacturers, medical device manufacturers have a high vested interest in quality, but have to be much more meticulous as they are more liable to lawsuits. In addition, a product recall would be extremely costly for the company: The manufacturer would either have to restart the entire process of acquiring patents, FDA approval and design, or forgo the entire project, potentially costing the company millions of dollars.

Not only do medical device manufacturers need to pay extra attention to the quality of their product and adhere to strict health and safety requirements, they also have to deal with the common pain points of manufacturing such as cost, cycle time, throughput, waste reduction and time to market. Test and inspection have become vital components to the success of a new medical device. These tests need to be scalable, reproducible and repeatable to handle mass production.

Why Leak Testing Is Critical

Many medical devices have fluid management systems to keep certain liquids separated, controlled or extracted. Improper fluid management can lead to serious health risks. Every piece of medical device equipment that has fluid management systems requires leak testing for medical devices. If a leak exists within the system, the wrong fluids could mix or go into the wrong part of a patient’s body, and the consequences could be fatal. The severe dangers of a poorly tested medical device is enough to make manufacturers strive for perfection when completing test and inspection procedures. 

The medical device testing market has more challenges than any other industry. Successful leak testing depends heavily on accurately considering certain factors of the application and making certain the leak testing application for the device is the right one. Some of these factors include part volume, geometry, material, leak rate, environment, cycle time, complexity of testing requirements, use of the tester and tester features. Only after considering all of these factors can a proper leak test machine for the device be created.

Medical Device Leak Testing Methods

The traditional method of leak testing is through an air bubble test: A part is submerged in water upon being internally pressurized. If bubbles appear and rise to the surface, a leak is present. This method is quite simple and very operator dependent, with low sensitivity and repeatability. For modern situations where production plants are producing hundreds of thousands of parts, it is inefficient to use an air bubble test that has a long cycle time.

Today, the most common form of leak testing for medical devices is done through an automated air leak test using air-pressure decay, vacuum decay or mass flow testing. Pressure decay consists of charging the test part with a prescribed pressure of compressed air, and then monitoring any drop in pressure within the part over a fixed period of time. If the pressure measured inside the part decreases during the test, a leak to the atmosphere would be suspected. For parts where a certain amount of leakage is acceptable, the difference between initial and final pressure readings is used to determine a pass or fail. 

A vacuum decay test consists of pulling a vacuum on a test chamber with the test part sealed inside. The vacuum level in the chamber is monitored for any increase in pressure (or decrease of vacuum) over a fixed period of time. If the chamber’s vacuum level decreases, a leak through the part that added air into the test chamber would be suspected. As with the above test, if a certain leakage rate is acceptable, the difference in initial and final vacuum readings determines if the part passes or fails.  

A mass flow test is used for parts that are either quite large or cannot structurally withstand static pressure or vacuum. In this test, a flow of air or inert gas is sent through the test part. The amount of gas sent to the part is precisely measured against the amount of gas that escapes the part, compared to the allowable leakage rate, and this difference is used to determine a pass or fail. 

All three of these methods can also be completed to a semi-automatic or fully automatic level. Automation helps in eliminating false positives, improving product quality, removing human error and reinforcing your paper trail by automatically saving digital records of test results. Each air leak testing method is chosen based on the application type. 

Another challenge engineers face when testing medical devices is the logistics of inspecting it. Many medical devices have small openings and multiple transfer paths, so correctly sealing and clamping them can be difficult. This is why it’s so important to choose an automation partner that carefully considers part volume, geometry and material before developing a leak test machine. The challenge is always creating low-cost, reliable sealing solutions that can work within an automated production system.

Leak Testing Automation

If you’re looking for nondestructive test methods and faster cycle times, automation is a viable solution for leak testing for medical devices parts. Automation allows manufacturers to reduce labor demands, increase yields and improve working conditions. Implementing an automated leak detection solution can help you gain customer confidence. It can also reduce total costs by way of needing less labor to properly test products with fewer errors.

With modern technology, medical device manufacturers gain the benefits of hands-off testing as well as consistent, error-free results. Other benefits of automating your leak testing include ease in meeting regulatory compliance, repeatable quality control, flexibility, labor offset, sustainability and responsible manufacturing.

If your automation projects are outsourced, it’s vital to select the right automation partner that can provide a transformative solution for your goals. It is most beneficial to select a partner with expertise in the design and implementation of your required leak testing machine. Check out this guide to choosing the right automation partner to see if your current partner is meeting expectations or if you need to explore more options.