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Particles Are a Sticky Subject

by | Aug 11, 2015


Due to the high manual labor content and the availability of terminal sterilization steps, medical devices are manufactured primarily in ISO Class 6-8 clean rooms. While these clean rooms are designed to control particles, fibers, and bio burden, the numerous contact points between operators and the device mandates that robust cleaning procedures be in place.

For example, it is often standard practice that work stations are wiped down each time an operator approaches or leaves the station.

In addition to work stations, gowning rooms are routinely mopped before and after shift changes and breaks.

It is also known that, despite rooms passing airborne particle checks, large surface fibers and particles are ever present sources of contamination.


It is well recognized that an outside-in approach is the best way to keep work stations and devices free of contamination. Simply stated, keeping contamination out of the clean room is far easier than dealing with it at the workstation.

But we know in medical device clean rooms, several factors mitigate against this ideal situation.

Let’s focus on two: high traffic and the use of disinfectants.


Since operators are a large source of contamination, airborne particle counts are widely used to measure room cleanliness while in operation.  Despite room counts being in control operators spend a great deal of time inspecting and cleaning large (50-150micron) fibers from devices.  In addition, there are excursion events where for days it seems no device is in spec for cleanliness; this necessitates extra inspection, device cleaning, and in some cases non-conformity reports and CAPA’s (which are often closed by triple cleaning the room).

Device firms that have investigated the excursions find the FM population diverse in the extreme which make root cause analysis very difficult.

So what is happening and what can be done?

Let’s go back to the triple cleaning of the room. Given that this often gets the room back in control this suggests that more robust cleaning of the large floor, wall, and ceiling surfaces could be a starting point.

This has, in fact, been validated at several device manufacturing facilities. It turns out that the disinfectants, applied daily to floors and weekly to walls and ceilings, tack down particles and fibers turning these large surfaces into FM storage containers.


What is needed is a cleaning solution that allows these surfaces to be stripped free of the disinfectant residues so that the entrapped contaminants can be removed from the room. This is easier said than done as typical mops and wipers do not scrub free the built up residues.

To solve this issue Foamtec has developed the Sahara + mop system. This mop is constructed with a uniquely tough, resilient foam that will not scratch even the softest surfaces but that will dislodge fibers and particles entrapped in the disinfectant residues. The other component to the mop head is a ribbed microfiber fabric that entraps and removes the soils dislodged from the surface. Each material is optimized to clean different types of particles. The Sahara foam is ideal for large fibers and hairs while the microfiber and polyester fabric remove hydrophilic and hydrophobic soils and particles.


The following video shows how cleaning can easily upgrade the cleanliness levels in clean rooms where medical devices are manufactured.


For more information about the Sahara+ System visit our website: