Manufacture/Assembly Contamination Assessment

[MediEng]

Hello all,

First time poster, long time reader

I'm a manufacturing/production engineer and my enquiry is more directed towards manufacturing processes and determining if their associated contamination is within acceptable limits. Hope someone can help me out... here it goes...

The company I work for is diversifying into the medical device industry and is currently working together with an Australian University to develop an electro-mechanical device intended for the Orthopedic sector.

The device will be used in a surgical environment and may come into contact to exposed tissue of the patient during use. A recent audit of our facility dictated our cleanroom must meet at least Class 100,000 (this will not be a problem from what we can see).

We intend to clean all moulding plastic components prior to assembly and sterilise the finished assembly using a third party (sub-contractor). The device requires me to screw together (self tap) & ultrasonically weld/stake plastic components within the assembly. I'm very familiar with these processes from prior experience and understand they can generate debris (contamination). I've seen examples online with processes such as these used in cleanrooms. I would like to know how to determine if a particular assembly equipment is suitable to be used to manufacture a device of this caliber?
Are there any guidelines/standards/recommendations out in the field which can help quantify the level of contamination generated by a particular assembly processes and determine if it is acceptable to use or not. If debris is generated are extraction units required..etc?

Much of the litrature I've examined has only focused on methods to maintain/improve air quality in cleanrooms but nothing as specific as this.


Appreciate any help, thanks in advance!

 

[Ronen E]

Hello MediEng and welcome to the Cove

I can't help you with any hard and fast rules, but I'll try to get the discussion going.

In my opinion you need to look at the issue from 2 perspectives, separately. One is bioburden / sterility and the other is particulate matter contamination (regardless of viability). Clean room environments are used for addressing either or both, depending on the product.

My impression is that you have the sterility aspect under control so I won't go into that.

The challenge with processes like those you describe is mainly the presence of particles / debris in the immediate product environment and on the product. The requirement specification regarding size of particles, number per volume unit, variance and distribution of the same, materials etc. are directly related to the nature of the product and the end use. I don't know of any generic guidelines, I think that each specialty has it's "industry standards" and unfortunately I'm not familiar enough with orthopaedic devices to provide specific pointers (could have, if you asked me about administration sets...). Generally, anything that goes into a surgical environment would need to be essentially debris-free, at least above the microscopic level.

Extractors are sometimes used however you'd need to validate their effectiveness. I also advise you to consider ES charges if you consider introducing air flows on/around plastic parts. Post production cleaning is another legitimate approach, but again you'll have to validate the method and also consider the added per-unit cost (probably not critical in your case).

Just my

Ronen.

 

[somashekar]

Hello all,

First time poster, long time reader

I'm a manufacturing/production engineer and my enquiry is more directed towards manufacturing processes and determining if their associated contamination is within acceptable limits. Hope someone can help me out... here it goes...

The company I work for is diversifying into the medical device industry and is currently working together with an Australian University to develop an electro-mechanical device intended for the Orthopedic sector.

The device will be used in a surgical environment and may come into contact to exposed tissue of the patient during use. A recent audit of our facility dictated our cleanroom must meet at least Class 100,000 (this will not be a problem from what we can see).

We intend to clean all moulding plastic components prior to assembly and sterilise the finished assembly using a third party (sub-contractor). The device requires me to screw together (self tap) & ultrasonically weld/stake plastic components within the assembly. I'm very familiar with these processes from prior experience and understand they can generate debris (contamination). I've seen examples online with processes such as these used in cleanrooms. I would like to know how to determine if a particular assembly equipment is suitable to be used to manufacture a device of this caliber?
Are there any guidelines/standards/recommendations out in the field which can help quantify the level of contamination generated by a particular assembly processes and determine if it is acceptable to use or not. If debris is generated are extraction units required..etc?

Much of the litrature I've examined has only focused on methods to maintain/improve air quality in cleanrooms but nothing as specific as this.


Appreciate any help, thanks in advance!

The activities that you have to perform which can generate particulate matter is the challenge to your next process of cleaning...
What about the post assembly cleaning ... ?
Would you use water, and do you have a water system to give you the required type of pure water for rinse / clean your assembly ... ? OR Would you use best quality IPA to do the same.
What about use of UHP N2 (Ultar High Pure N2) for the final flush of the assembly done under a laminar bench.
My take is that you establish some such system as said above and validate it through post cleaning particulate count. Set the system to operate under defined controlled conditions and make sure the challenge does not increase.

 

[Pads38]

After reading Ronen's post I was prompted to recall a test I have been involved with. This comes form a pacemakers standard (EN 45502-2-1:2003) and has probably been replaced by now.

14 Protection from unintentional biological effects being caused by the active implantable medical device

14.2
Replacement:
When the ACTIVE IMPLANTABLE MEDICAL DEVlCE is used as intended by the manufacturer, any part of the device intended to be in contact with body fluids shall cause no unacceptable release of particulate matter.

Test: The ACTIVE IMPLANTABLE MEDICAL DEVICE shall be removed aseptically from the NON-REUSABLE PACK. The implantable part shall be immersed in a bath of saline solution, approximately 9 gll and suitable for injection, in a neutral glass container. The volume of the saline in millilitres shall be 5 1 0,5 times the numerical value of the surface area of the implantable part expressed in cmz. The container shall be covered with a glass lid and maintained at 37 °C 1 2 °C for between 8 h and 18 h, the bath being agitated throughout the period.....

Compliance shall be confirmed if the excess average count of particles from the specimen compared to the reference sample does not exceed 100 per ml greater than 5,0 pm and does not exceed 5 per ml greater than 25 um.

Note that I have edited out some of the detail, to protect copyright.

If your device is orthopaedic related I would suggest that their is probably a similar test and requirement in standards for, say, hip implants. That could be a useful starting point.

 

[MediEng]

Thank you all for your input, it is very much appreciated... I welcome further input if there is any. Here are my comments to each response.

Pads38: I will attempt to look for a guideline test similar to this for our application.

Ronen E & somashekar: I tend to agree with your post cleaning & validation idea. Considering the device is electro-mechanical and will have a battery device installed at the end of assembly I believe this will rule out a 'liquid' wash as the device will be energised by this stage. I'm steering towards the Ultar High Pure N2 for the final flush of the assembly done under a laminar bench - not familiar with this process but will investigate further. Validation will be needed - trick is to find a validation procedure as Pads38 has mentioned.

Thanks again - if there is anything else anyone can offer it would certainly help.

 

[Ronen E]

Thank you all for your input, it is very much appreciated... I welcome further input if there is any. Here are my comments to each response.

Pads38: I will attempt to look for a guideline test similar to this for our application.

Ronen E & somashekar: I tend to agree with your post cleaning & validation idea. Considering the device is electro-mechanical and will have a battery device installed at the end of assembly I believe this will rule out a 'liquid' wash as the device will be energised by this stage. I'm steering towards the Ultar High Pure N2 for the final flush of the assembly done under a laminar bench - not familiar with this process but will investigate further. Validation will be needed - trick is to find a validation procedure as Pads38 has mentioned.

Thanks again - if there is anything else anyone can offer it would certainly help.

In my mind the validation procedure could be quite generic, with necessary adjustments - just look up "cleaning validation". The unique part is the acceptance criteria.