What is a clean room in Biomedical engineering?

A cleanroom or clean room is an engineered space, which maintains a very low concentration of airborne particulates. The clean room is well-isolated, well-controlled from contamination, and actively cleaned. Such rooms are commonly needed for scientific research, such as semiconductor manufacturing. A cleanroom is designed to keep everything from dust to airborne organisms, or vaporized particles, away from it, and so from whatever material is being handled inside it.

Features of the clean room

1. It has an air filtration and ventilation system so that it can continuously bring air without particles into the room
2. It is made of materials that do not create particles and do not spread particles
3. The processes that are carried out in it are designed in such a way that they do not create particles.
4. The people present in it should wear clothes in such a way that no particles can pass through them and also The clothes themselves do not produce particles.
5. And finally, its rules should be such that the transmission of particles in certain areas is as low as possible.

Clean room requirements

A clean room is an environment that should be away from any pollution and contaminated particles. To achieve this goal, it is important to meet and create a series of requirements in the clean room. The requirements of a clean room include the following:

• Standard
• classification
• Particle measurement in the direction of room monitoring

Standard in clean room

According to the ISO 14644-1 standard, the clean room must be made in such a way that it is free from any contaminated particles and its numerical density can be controlled. This criterion is done according to the space requirements of that room. Other parameters are also measured in this standard. These parameters are:

• temperature
• humidity
• Pressure

Clean Room Classification

Pollution in the clean room

•Pollution is a process that leads to the settling of polluting particles on materials, tissues, or becomes levels. One of the most important types of pollution is particles. This is pollution which

It can disrupt the natural flow of air in the room.

• Molecular pollution

• Sources of molecular pollution include the release of toxic gases in the air, vapors, alcohol, paint, glue, etc. It should be noted that particle filters have the ability to remove pollutants They do not have molecular
• Surface contamination

• Sources of surface pollution include fingerprints, skin oil, hand cream, gel, oil and grease, face powder, softeners, wax, etc.

• Pollution caused by particles
• Sources that cause pollution caused by particles include people (skin, skin, hair, clothing fibers, etc.), objects that produce particles (paper), Cardboard boxes, etc., abrasion actions (sawing, sanding, etc.), and…

GMP standard

In this type of cleanroom standard, the number of particles is counted in two ways: ready for work and during work. The classes of this room are A, B, C, and D according to the GMP classification with classes 100 to 100,000 of the D version of the US federal standard with the number of particles of a particular size, which per cubic foot of air in a state without activity in Any degree is allowed, compared. In order to reach the conditions of grades A, B, or C, one should pay attention to parameters such as the dimensions and space of the room, and the number of personnel and equipment in the room.

Particle measurement

This discussion is related to the particle, which is a general term. A particle is a substance that cannot be seen with the naked eye and can be seen with the use of precise and advanced instruments. The measurement of this number of particles is called particle measurement. Particle measurement is done to monitor the clean room, which has different methods. The use of particle counting and checking the airflow and the use of culture mediums in different places of the separation room are among the methods of particle measurement.

In fact, other important factors in clean room requirements are clean room architecture, dressing in this room, and clean room cleaning.

Classification of airflow types

Clean rooms are divided into 4 different types based on the airflow used in them:

• Conventional (clean room with indirect airflow)

• The air passes through the filters installed in the ceiling
• clean air filter with air

• The room is mixed and then exits through the valves located at the bottom of the walls.

The role of ventilation in the clean room

One of the main requirements of a clean room in its design is correct and basic ventilation based on the standards of this room. In the ventilation of these rooms, air conditioning systems are installed in the way of air entry. To minimize the number of polluting particles by absorbing and filtering the air pollution entering the room.

The incoming airflow of clean rooms is divided into three types.    

One-way laminar flow: In laminar flow, the air enters the room in a linear and parallel manner through the ceiling (vertical) and wall (horizontal) vents and directs the air out through the exhaust valve.

 Unidirectional (clean room with direct airflow):

• The volume of air in rooms with one-way flow is 10 to 100 times larger than the rooms with the ventilation system.

It is conventional, so they are much more expensive. This type of direct airflow,

It is known as Laminar flow and is used for clean rooms with classes 1, 10, and 100.

Its speed is between 0.3 and 0.45 s/m (60 to 90 min/ft) in the entire air space.

low mixed (combined flow)

• In the combined airflow, the airflow can be designed in such a way that the air enters from the horizontal wall and

Get off the floor. This type of design is done due to the existence of special needs.

• Another type of combined flow that is proposed to create a very high degree of cleanliness in a room

is, the entry of 100% filtered air from the ceiling and one wall, and its exit is from the floor and the opposite wall.

It is also a part of the opposite wall which is considered as an air shower and entrance.

• microenvironment or Isolators (isolated room or environment with small areas

Clean)

• This type of airflow is used in the clean room to achieve the highest level of pollution control. The isolation room has a direct air conditioner.

Cleanroom used for the production of microsystems. The yellow (red-green) lighting is necessary for photolithography, to prevent unwanted exposure of photoresist to light of shorter wavelengths.

Typical cleanroom head garment

Cleanroom cabin for precision measuring tools.

Cleanroom for microelectronics manufacturing with fan filter units installed in the ceiling grid.