What testing would you run to determine if a device is "Clean"?


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What testing would you all run to determine if a device is "clean"? What are acceptable levels during those tests for a clean device?

We have asked our regulatory consultants this question, and got a bit of flaky answers. I also haven't seen anywhere that really defines what "clean" is/means.

Take initial bioburden during biocompatibility testing and use that as a baseline for future bioburden levels? Same thing for particulates?


Quite Involved in Discussions
Re: "Clean" device measurements

The type of testing depends on the type of residue expected.

ASTM F2847 suggested testing methods for different types of residue, and there are helpful resources here:

(broken link removed)

and here:


The first link shows a chart for the different testing methods for various types of residue.

Establishing acceptable cleanliness limits is left to the manufacturer and can as you said rely on biocompatibility testing. What is important is that the limits are justified.

Ronen E

Problem Solver
Re: "Clean" device measurements

It all depends on the intended use.

It's up to you to decide what's important and how is "clean" defined. Then you can set limits and derive test methods from what you're looking for.

Biocompatibility should be tested (if testing is necessary) on devices as they're serially manufactured. If bioburden is not important for the intended use and the manufacturing environment doesn't particularly attenuate bioburden, this is how biocompatibility should be tested (on "dirty" devices). If the device passes biocompatibility testing in its "natural" state there is no special reason to make it / keep it cleaner than as-tested, nor to actively monitor its cleanliness.

If bioburden is of importance for the intended use there are specific published standards which include test methods. The pass/fail criteria would, however, depend on the specific intended use, ie on what clinically matters.

Particulate contamination is tricky and I'm not aware of a wide consensus on acceptance criteria, even within specific application fields such as drug delivery. Talk to clinical opinion leaders in your specific field to get a feel for the requirements.

I wouldn't whole-heartedly support testing for residues that don't make a difference for the intended use, even if they're expected. Gross contamination would be obvious, and besides, it should be addressed through proper design & process controls rather than through testing (QA rather than QC).
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Re: What testing would you all run to determine if a device is "clean"?

Great, thank you both for the thoughtful responses.


Trusted Information Resource
Re: What testing would you all run to determine if a device is "clean"?

Lick my finger, rub it on the product, lick my finger again.

Sorry, rough day. I did determine exactly what kind of soft drink had been spilled into a customer's computer returned "under warranty" in that manner once.

Customer Service report noted " Dr. Pepper " as the cause of failure.
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