Visual Inspection of Medical Pouches
A human eye is an incredible machine. Despite our incredible computer and sensor technologies, we can’t even begin to touch the surface of the human eye’s amazing capabilities. It has a 200 degree viewing angle, can see 2.7 million colors and has a possible contrast ratio of about 1,000,000 to 1 [Wikipedia]. The eye is the ultimate inspection device, and yet we seem to lean away from the human eye’s capability to other empirical data portals. In the medical device packaging industry, inspection and monitoring are king. In order for us to be certain that the medical devices that we cocoon to market are kept viable and efficacious, we need to use all tools available in science.
Historically, the visual inspection of sterile device pouches has presented our industry with a host of problems – inspector’s visual acuity and, of course, the most important downfall, and the interpreter’s judgment. The other large problem with visual seal inspection has been the variety of lighting that the observer has used, such as ambient room light, both incandescent and fluorescent, daylight, both filtered and direct, and also angles of light used, back lighting and front direct lighting.
It became a passion in our own sterile device package integrity lab to find a sensible standard that would also determine what type of magnification should be used in visual inspection. We have tried jeweler’s loops, microscopes, and magnifying glasses. They all seemed to be good under some seal failure models, but not a good panacea of magnification was found. Our sterile device-packaging group would hike each morning on a mountain trail in the San Gabriel Mountains in Southern California. These walks were fortified with discussions of work and seal evaluations.
We noticed in late fall, the low angle of light in the Southern horizon would create a completely different experience for us on our walk. The small golf-ball sized rocks that we never noticed before seemed to completely litter our hiking trail. It was the low angle of light that exaggerated all the nooks and crannies on the micro-topography of our hiking trail. I wondered if this side lighting would benefit our seal evaluation to also explore seal anomalies such as pleats and folds. We simply took a small maglight and had it illuminate across a sealed area of a TyVek and Mylar pouch and was amazed at a similar outcome on the pouch. Not only could we were able to see non-homogenous seals, we could also easily see pleats and folds. We discovered that magnifying the pouch 3x blended perfect amount of magnification for all observers and we fixtured up a simple prototype that become a visual inspection workhorse in our seal integrity lab.
Customers would ask us about visual inspection and the ASTM 1886 standard and how they might use it in their lab to identify possible seal failures in a non-destructive way before it became critical. Because we realized this device was very novel and could greatly benefit our customers, we decided to file for a US patent and created a production model of the VIU unit and even incorporated some reference graphics that would help our users better identify problems on the critical sealed area of their pouch. The timing could not have been better for this device as the industry now asks sterile device packagers to evaluate seal strength and to understand seal integrity as well. One of the best ways to manage seal integrity, in our opinion, is through the non-destructive means of visual inspection and we truly feel that we have contributed an important device to the ends of visual inspection.
No, visual inspection is not a panacea in terms of evaluating total seal value, but it is certainly an important tool in the whole quality team’s total toolkit. One of the biggest frustrations that we have seen during the nearly 20 years working with medical device companies and their packaging line is that many quality teams are brought in either through outside consultancies or through effectively a one-time function that basically creates a very robust validation on the outset, but the validation creeps to very minimal over the life of their packaging program. Visual inspection is a good way to keep seal integrity managed in-process and in the cleanroom. Again, it is not designed to replace peel or burst testing, but it is literally another peek into the full integrity of the sterile pouch.
In the second iteration of the view device, it will include a simple pass/fail button that will allow operators to visually inspect a seal, pass or fail it, and the device will time/date stamp the pass/failure of the seal that will be easily downloadable into a spreadsheet at the year’s end or at the time of inspection. For now, users are simply evaluating the visual merits of the pouch and using the provided log sheet to record the integrity functions throughout the year. This adds another important layer of evaluation and in an industry where a sterile implant could be a matter of life or death, it holds up to the seriousness of our jobs.
In the book, Validating Sterile Device Packaging, the author lists visual seal inspection as #1 for seal integrity. Surprisingly, little exists in our industry to meet this visual protocol and the fact that there is no mechanized device such as the VIU is somewhat surprising to our integrity group. We are happy, however, to offer up our device with all the supporting reference data. We believe so much in the side-lighting technology that we have incorporated this visual inspection tool into our model MS-451PV packaging sealer. It also is an industry first to include a peel-tester. This machine represents our passion for testing, and testing often. You can learn more about our packaging integrity lab by visiting this link or you can visit this link and see a quick two-minute video presentation on how the VIU device works.
The developmental costs of this device were very high and in terms of a sensible market mix as a finished product, our management is still scratching its head, so we hope you will support this device as it was truly developed to help our device customers and we believe it would be a great gift to your total device sterilization program. For more information about the VIU box, please call our engineering group at 800-550-3854 x112.