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A cleanroom or clean room is an engineered space, which maintains a very low concentration of airborne particulates. It is well isolated, well-controlled from contamination, and actively cleansed. Such rooms are commonly needed for scientific research, and in industrial production for all nanoscale processes, such as semiconductor manufacturing. A cleanroom is designed to keep everything from dust, to airborne organisms, or vaporised particles, away from it, and so from whatever material is being handled inside it.
The other way around, a cleanroom can also help keep materials escaping from it. This is often the primary aim in hazardous
biology
Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary i ...
and
nuclear work, in
pharmaceutics
Pharmaceutics is the discipline of pharmacy that deals with the process of turning a new chemical entity (NCE) or old drugs into a medication to be used safely and effectively by patients. It is also called the science of dosage form design. The ...
and in
virology
Virology is the Scientific method, scientific study of biological viruses. It is a subfield of microbiology that focuses on their detection, structure, classification and evolution, their methods of infection and exploitation of host (biology), ...
.
Cleanrooms typically come with a cleanliness level quantified by the number of particles per cubic meter at a predetermined molecule measure. The ambient outdoor air in a typical urban area contains 35,000,000 particles for each cubic meter in the size range 0.5 μm and bigger, equivalent to an ISO 9 certified cleanroom. By comparison an ISO 14644-1 level 1 certified cleanroom permits no particles in that size range, and just 12 particles for each cubic meter of 0.3 μm and smaller. Semiconductor facilities often get by with level 7, while level 1 facilities are exceedingly rare.
History
The modern cleanroom was invented by American
physicist
A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe.
Physicists generally are interested in the root or ultimate caus ...
Willis Whitfield
Willis Whitfield (December 6, 1919 – November 12, 2012) was an American physicist and inventor of the modern cleanroom, a room with a low level of pollutants used in manufacturing or scientific research. His invention earned him the nickna ...
.
As employee of the
Sandia National Laboratories
Sandia National Laboratories (SNL), also known as Sandia, is one of three research and development laboratories of the United States Department of Energy's National Nuclear Security Administration (NNSA). Headquartered in Kirtland Air Force Ba ...
, Whitfield created the initial plans for the cleanroom in 1960.
[ Prior to Whitfield's invention, earlier cleanrooms often had problems with particles and unpredictable ]airflow
Airflow, or air flow, is the movement of air. The primary cause of airflow is the existence of air. Air behaves in a fluid manner, meaning particles naturally flow from areas of higher pressure to those where the pressure is lower. Atmospheric a ...
s. Whitfield designed his cleanroom with a constant, highly filtered air flow to flush out impurities.[ Within a few years of its invention in the 1960s, Whitfield's modern cleanroom had generated more than US$50 billion in sales worldwide (approximately $ billion today).]
The majority of the integrated circuit manufacturing facilities in Silicon Valley
Silicon Valley is a region in Northern California that serves as a global center for high technology and innovation. Located in the southern part of the San Francisco Bay Area, it corresponds roughly to the geographical areas San Mateo County ...
were made by three companies: MicroAire, PureAire, and Key Plastics. These competitors made laminar flow units, glove boxes, clean rooms and air showers, along with the chemical tanks and benches used in the 'Wet Process' building of integrated circuits. These three companies were the pioneers of the use of Teflon
Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. It is one of the best-known and widely applied PFAS. The commonly known brand name of PTFE-based composition is Teflon by Chemou ...
for airguns, chemical pumps, scrubbers, water guns, and other devices needed for the production of integrated circuits. William (Bill) C. McElroy Jr. worked as engineering manager, drafting room supervisor, QA/QC, and designer for all three companies and his designs added 45 original patents to the technology of the time. McElroy also wrote a four-page article for MicroContamination Journal, wet processing training manuals, and equipment manuals for wet processing and clean rooms.
Overview
A clean room is a necessity in semiconductor manufacturing
Semiconductor device fabrication is the process used to manufacture semiconductor devices, typically integrated circuit (IC) chips such as modern computer processors, microcontrollers, and memory chips such as NAND flash and DRAM that are pres ...
, rechargeable battery
A rechargeable battery, storage battery, or secondary cell (formally a type of Accumulator (energy), energy accumulator), is a type of electrical battery which can be charged, discharged into a load, and recharged many times, as opposed to ...
industry, the life sciences
This list of life sciences comprises the branches of science that involve the scientific study of life – such as microorganisms, plants, and animals including human beings. This science is one of the two major branches of natural science, the ...
, and any other field that is highly sensitive to environmental contamination.
Cleanrooms can range from the very small to the very large. On the one hand, a single user laboratory can be built to cleanroom standards within several square meters, and on the other entire manufacturing facilities can be contained within a cleanroom with factory floors covering thousands of square meters. Between the large and the small, there are also modular cleanrooms. They have been argued to lower costs of scaling the technology, and to be less susceptible to catastrophic failure.
With such a wide area of application, not every cleanroom is the same. For example, the rooms utilized in semiconductor manufacturing need not be sterile
Sterile or sterility may refer to:
*Asepsis, a state of being free from biological contaminants
* Sterile (archaeology), a sediment deposit which contains no evidence of human activity
*Sterilization (microbiology), any process that eliminates or ...
(i.e., free of uncontrolled microbes);, while the ones used in biotechnology usually must be. Vice versa, operating room
Operation or Operations may refer to:
Arts, entertainment and media
* ''Operation'' (game), a battery-operated board game that challenges dexterity
* Operation (music), a term used in musical set theory
* ''Operations'' (magazine), Multi-Man ...
s need not be absolutely pure of nanoscale inorganic salts, such as rust, while nanotechnology absolutely requires it. What then is common to all cleanrooms is strict control of airborne particulates, possibly with secondary decontamination of air, surfaces, workers entering the room, implements, chemicals, and machinery.
Sometimes particulates exiting the compartment are also of concern, such as in research
Research is "creativity, creative and systematic work undertaken to increase the stock of knowledge". It involves the collection, organization and analysis of evidence to increase understanding of a topic, characterized by a particular att ...
into dangerous viruses
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea.
Since Dmitri Ivanovsky's 1 ...
, or where radioactive materials are being handled.
Basic construction
First, outside air entering a cleanroom is filter
Filter, filtering or filters may refer to:
Science and technology
Computing
* Filter (higher-order function), in functional programming
* Filter (software), a computer program to process a data stream
* Filter (video), a software component tha ...
ed and cooled by several outdoor air handler
An air handler, or air handling unit (often abbreviated to AHU), is a device used to regulate and circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system. An air handler is usually a large metal box containing a blowe ...
s using progressively finer filters to exclude dust.
Within, air is constantly recirculated through fan units containing high-efficiency particulate absorbing filters (HEPA
HEPA (, high-efficiency particulate air) filter, also known as high-efficiency particulate absorbing filter and high-efficiency particulate arrestance filter, is an efficiency standard of air filters.
Filters meeting the HEPA standard must sa ...
), and/or ultra-low particulate air (ULPA
ULPA is an acronym for "Ultra-low Penetration Air (filter)". An ULPA filter can remove from the air at least 99.999% of dust, pollen, mold, bacteria and any airborne particles with a minimum particle penetration size of 120 nanometres (0.12 Â ...
) filters to remove internally generated contaminants. Special lighting fixtures, walls, equipment and other materials are used to minimize the generation of airborne particles. Plastic sheets can be used to restrict air turbulence, if the cleanroom design is of the laminar airflow type.
Air temperature and humidity levels inside a cleanroom are tightly controlled, because they affect the efficiency and means of air filtration. If a particular room requires low enough humidity to make static electricity a concern, it too will be controlled by e.g. introducing controlled amounts of charged ions into the air, using a corona discharge
A corona discharge is an electrical discharge caused by the ionization of a fluid such as air surrounding a conductor (material), conductor carrying a high voltage. It represents a local region where the air (or other fluid) has undergone e ...
. Static discharge is of particular concern in the electronics industry, where it can instantly destroy components and circuitry.
Equipment inside any cleanroom is designed to generate minimal air contamination. The selection of material for the construction of a cleanroom should not generate any particulates, hence monolithic epoxy or polyurethane floor coating is preferred. Buffed stainless steel or powder-coated mild steel sandwich partition panels and ceiling panel are used, instead of iron alloys prone to rusting and then flaking. Corners like the wall to wall, wall to floor, wall to ceiling are avoided by providing coved surface and all joints need to be sealed with epoxy sealant to avoid any deposition or generation of particles at the joints, by vibration and friction.
Air flow principles
Cleanrooms maintain particulate-free air through the use of either HEPA
HEPA (, high-efficiency particulate air) filter, also known as high-efficiency particulate absorbing filter and high-efficiency particulate arrestance filter, is an efficiency standard of air filters.
Filters meeting the HEPA standard must sa ...
or ULPA
ULPA is an acronym for "Ultra-low Penetration Air (filter)". An ULPA filter can remove from the air at least 99.999% of dust, pollen, mold, bacteria and any airborne particles with a minimum particle penetration size of 120 nanometres (0.12 Â ...
filters employing laminar or turbulent air flow principles. Laminar, or unidirectional, air flow systems direct filtered air downward or in horizontal direction in a constant stream towards filters located on walls near the cleanroom floor or through raised perforated floor panels to be recirculated. Laminar air flow systems are typically employed across 80% of a cleanroom ceiling to maintain constant air processing. Stainless steel or other non shedding materials are used to construct laminar air flow filters and hoods to prevent excess particles entering the air. Turbulent, or non unidirectional, air flow uses both laminar air flow hoods and nonspecific velocity filters to keep air in a cleanroom in constant motion, although not all in the same direction. The rough air seeks to trap particles that may be in the air and drive them towards the floor, where they enter filters and leave the cleanroom environment. US FDA and EU have laid down guidelines and limit for microbial contamination which is very stringent to ensure freedom from microbial contamination in pharmaceutical products. Plenum
Plenum may refer to:
* Plenum chamber, a chamber intended to contain air, gas, or liquid at positive pressure
* Plenism, or ''Horror vacui'' (physics) the concept that "nature abhors a vacuum"
* Plenum (meeting), a meeting of a deliberative assem ...
s between air handler
An air handler, or air handling unit (often abbreviated to AHU), is a device used to regulate and circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system. An air handler is usually a large metal box containing a blowe ...
s and fan filter unit
A fan filter unit (FFU) is a type of motorized air filtering equipment. It is used to supply purified air to cleanrooms, laboratories, medical facilities or microenvironments by removing harmful airborne particles from recirculating air. The units ...
s along with sticky mat
A sticky mat, also called a tacky mat or cleanroom mat, is a mat with an adhesive surface that is placed at the entrances or exits to certain workplaces to remove contaminants from the bottoms of footwear and wheeled carts such as hand truc ...
s may also be used.
In addition to air filters, clean rooms can also use ultraviolet light
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...
to disinfect the air. UV devices can be fitted into ceiling light fixtures and irradiate air, killing potentially infectious particulates, including 99.99 percent of airborne microbial and fungal contaminants. UV light has previously been used to clean surface contaminants in sterile environments such as hospital operating rooms. Their use in other clean rooms may increase as equipment becomes more affordable. Potential advantages of UV-based decontamination includes a reduced reliance on chemical disinfectants and the extension of HVAC filter life.
Cleanrooms of different kinds
Some cleanrooms are kept at a positive pressure
Positive pressure is a pressure within a system that is greater than the environment that surrounds that system. Consequently, if there is any leak from the positively pressured system it will egress into the surrounding environment. This is in ...
so if any leaks occur, air leaks out of the chamber instead of unfiltered air coming in. This is most typically the case in semiconductor manufacturing, where even minute amounts of particulates leaking in could contaminate the whole process, while anything leaking out would not be harmful to the surrounding community. The opposite is done e.g. in the case of high level bio-laboratories that handle dangerous bacteria or viruses; those are always held at negative pressure
Negative pressure may refer to:
* Negative value of a pressure variable
* Negative room pressure, a ventilation technique used to avoid contaminating outside areas
* Negative pressure ventilator, also known as an iron lung
* Negative-pressure wou ...
, with the exhaust being passed through high efficiency filters, and further sterilizing procedures. Both are still cleanrooms, because the particulate level inside is maintained within very low limits.
Some cleanroom HVAC
Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. HV ...
systems control the humidity
Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present.
Humidity depe ...
to such low levels that extra equipment like air ionizers are required to prevent electrostatic discharge
Electrostatic discharge (ESD) is a sudden and momentary flow of electric current between two electrically charged objects caused by contact, an short circuit, electrical short or dielectric breakdown. A buildup of static electricity can be caused ...
problems. This is a particular concern within the semiconductor business, because static discharge can easily damage modern circuit designs. On the other hand, active ions in the air can harm exposed components as well. Because of this most workers in high electronics and semiconductor facilities have to wear conductive boots while working. Low-level cleanrooms may only require special shoes, with completely smooth soles that do not track in dust or dirt. However, for safety reasons, shoe soles must not create slipping hazards. Access to a cleanroom is usually restricted to those wearing a cleanroom suit
A cleanroom suit, clean room suit, or bunny suit, is an overall garment worn in a cleanroom, an environment with a controlled level of contamination. One common type is an all-in-one coverall worn by semiconductor and nanotechnology line producti ...
, including the necessary machinery.
In cleanrooms in which the standards of air contamination are less rigorous, the entrance to the cleanroom may not have an air shower. An anteroom (known as a "gray room") is used to put on clean-room clothing. This practice is common e.g. in many nuclear power plants, which operate as low-grade inverse pressure cleanrooms, as a whole.
Recirculating vs. One pass cleanrooms
Recirculating cleanrooms return air to the negative pressure plenum via low wall air returns. The air then is pulled by HEPA fan filter units back into the cleanroom. The air is constantly recirculating and byu continuously passing thru HEPA filtration removing particles from the air each time. Another advantage of this design is air conditioning can be incorporated.
One pass cleanrooms draw air from outside the cleanroom, pass it thru HEPA fan filter units into the cleanroom. The air then leaves thru exhaust grills to outside the cleanroom. The advantage of this approach is the lower cost. The disadvantages are short HEPA fan filter live, worse particle counts than similar recirculating cleanroom, and cannot accommodate air conditioning.
Operating procedure
In order to minimize the carrying of particulate by a person moving into the cleanroom, staff enter and leave through airlock
An airlock, air-lock or air lock, often abbreviated to just lock, is a compartment with doors which can be sealed against pressure which permits the passage of people and objects between environments of differing pressure or atmospheric compo ...
s (sometimes including an air shower stage), and wear protective clothing such as hoods, face masks, gloves, boots, and coveralls.
Common materials such as paper
Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distributed ...
, pencil
A pencil () is a writing or drawing implement with a solid pigment core in a protective casing that reduces the risk of core breakage, and keeps it from marking the user's hand.
Pencils create marks by physical abrasion, leaving a trail ...
s, and fabric
Textile is an umbrella term that includes various fiber-based materials, including fibers, yarns, filaments, threads, different fabric types, etc. At first, the word "textiles" only referred to woven fabrics. However, weaving is not the ...
s made from natural fibers are often excluded, because they shed particulates in use.
Particle levels are usually tested using a particle counter
A particle counter is used for monitoring and diagnosing particle contamination within specific clean media, including air, water and chemicals. Particle counters are used in a variety of applications in support of clean manufacturing practices, ...
and microorganisms detected and counted through environmental monitoring methods. Polymer
A polymer (; Greek '' poly-'', "many" + ''-mer'', "part")
is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
tools used in cleanrooms must be carefully determined to be chemically compatible with cleanroom processing fluids as well as ensured to generate a low level of particle generation.
When cleaning, only special mop
A mop (such as a floor mop) is a mass or bundle of coarse strings or yarn, etc., or a piece of cloth, sponge or other absorbent material, attached to a pole or stick. It is used to soak up liquid, for cleaning floors and other surfaces, to mop ...
s and bucket
A bucket is typically a watertight, vertical Cylinder (geometry), cylinder or Truncation (geometry), truncated Cone (geometry), cone or square, with an open top and a flat bottom, attached to a semicircular carrying handle (grip), handle called ...
s are used. Cleaning chemicals used tend to involve sticky elements to trap dust, and may need a second step with light molecular weight solvents to clear. Cleanroom furniture is designed beforehand to produce a minimum of particles, and is easy to clean.
A cleanroom is as much a process and a meticulous culture to maintain, as it is a space as such.
Personnel contamination of cleanrooms
The greatest threat to cleanroom contamination comes from the users themselves. In the healthcare and pharmaceutical sectors, control of microorganisms is important, especially microorganisms likely to be deposited into the air stream from skin shedding. Studying cleanroom microflora is of importance for microbiologists and quality control personnel to assess changes in trends. Shifts in the types of microflora may indicate deviations from the "norm" such as resistant strains or problems with cleaning practices.
In assessing cleanroom micro-organisms, the typical flora are primarily those associated with human skin (Gram-positive cocci), although microorganisms from other sources such as the environment (Gram-positive rods) and water (Gram-negative rods) are also detected, although in lower number. Common bacterial genera include ''Micrococcus'', ''Staphylococcus'', ''Corynebacterium'', and ''Bacillus'', and fungal genera include ''Aspergillus'' and ''Penicillium''.
Cleanroom classification and standardization
Cleanrooms are classified according to the number and size of particles permitted per volume of air. Large numbers like "class 100" or "class 1000" refer to FED-STD-209E FED-STD-209 E ''Airborne Particulate Cleanliness Classes in Cleanrooms and Cleanzones'' was a federal standard concerning classification of air cleanliness, intended for use in environments like cleanrooms. The standard based its classifications on ...
, and denote the number of particles of size 0.5 μm or larger permitted per cubic foot of air. The standard also allows interpolation; for example SNOLAB
SNOLAB is a Canadian underground science laboratory specializing in neutrino and dark matter physics. Located 2 km below the surface in Vale's Creighton nickel mine near Sudbury, Ontario, SNOLAB is an expansion of the existing facilities con ...
is maintained as a class 2000 cleanroom.
A discrete, light-scattering airborne particle counter is used to determine the concentration of airborne particles, equal to and larger than the specified sizes, at designated sampling locations.
Small numbers refer to ISO 14644-1
ISO 14644 Standards were first formed from the US Federal Standard 209E Airborne Particulate Cleanliness Classes in Cleanrooms and Clean Zones. The need for a single standard for cleanroom classification and testing was long felt. After ANSI and ...
standards, which specify the decimal logarithm
In mathematics, the logarithm is the inverse function to exponentiation. That means the logarithm of a number to the base is the exponent to which must be raised, to produce . For example, since , the ''logarithm base'' 10 o ...
of the number of particles 0.1 μm or larger permitted per m3 of air. So, for example, an ISO class 5 cleanroom has at most 105 particles/m3.
Both FS 209E and ISO 14644-1 assume log-log relationships between particle size and particle concentration. For that reason, zero particle concentration does not exist. Some classes do not require testing some particle sizes, because the concentration is too low or too high to be practical to test for, but such blanks should not be read as zero.
Because 1 m3 is about 35 ft3, the two standards are mostly equivalent when measuring 0.5 μm particles, although the testing standards differ. Ordinary room air is around class 1,000,000 or ISO 9.
ISO 14644-1 and ISO 14698
ISO 14644-1
ISO 14644 Standards were first formed from the US Federal Standard 209E Airborne Particulate Cleanliness Classes in Cleanrooms and Clean Zones. The need for a single standard for cleanroom classification and testing was long felt. After ANSI and ...
and ISO 14698 are non-governmental
A non-governmental organization (NGO) or non-governmental organisation (see American and British English spelling differences#-ise, -ize (-isation, -ization), spelling differences) is an organization that generally is formed independent from g ...
standards developed by the International Organization for Standardization
The International Organization for Standardization (ISO ) is an international standard development organization composed of representatives from the national standards organizations of member countries. Membership requirements are given in Ar ...
(ISO). The former applies to clean rooms in general (see table below); the latter to cleanrooms where biocontamination may be an issue. Since the strictest standards have been achieved only for space applications, it is sometimes difficult to know whether they were achieved in vacuum or standard conditions.
ISO 14644-1
ISO 14644 Standards were first formed from the US Federal Standard 209E Airborne Particulate Cleanliness Classes in Cleanrooms and Clean Zones. The need for a single standard for cleanroom classification and testing was long felt. After ANSI and ...
defines the maximum concentration of particles per class and per particle size with the following formula
Where is the maximum concentration of particles in a volume of 1m of airborne particles that are equal to, or larger, than the considered particle size which is rounded to the nearest whole number, using no more than three significant figures, is the ISO class number, is the size of the particle in m and 0.1 is a constant expressed in m. The result for standard particle sizes is expressed in the following table.
US FED STD 209E
US FED-STD-209E FED-STD-209 E ''Airborne Particulate Cleanliness Classes in Cleanrooms and Cleanzones'' was a federal standard concerning classification of air cleanliness, intended for use in environments like cleanrooms. The standard based its classifications on ...
was a United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
federal
Federal or foederal (archaic) may refer to:
Politics
General
*Federal monarchy, a federation of monarchies
*Federation, or ''Federal state'' (federal system), a type of government characterized by both a central (federal) government and states or ...
standard. It was officially cancelled by the General Services Administration
The General Services Administration (GSA) is an independent agency of the United States government established in 1949 to help manage and support the basic functioning of federal agencies. GSA supplies products and communications for U.S. gover ...
on November 29, 2001, but is still widely used.
Current regulating bodies include: ISO, USP 800, US FED STD 209E (previous standard, still used)
* Drug Quality and Security Act (DQSA) created in Nov. 2013 in response to drug compounding deaths and serious adverse events.
* The Federal Food, Drug, and Cosmetic Act (FD&C Act) created specific guidelines and policies for human compounding.
** 503A addresses compounding by state or federally licensed facility by licensed personnel (pharmacist/ physicians)
** 503B pertaining to outsourcing facilities need direct supervision from a licensed pharmacist and do not need to be a licensed pharmacy. Facility is licensed through the Food and Drug Administration (FDA)
EU GMP classification
EU GMP guidelines are more stringent than others, requiring cleanrooms to meet particle counts at operation (during manufacturing process) and at rest (when manufacturing process is not carried out, but room AHU is on).
BS 5295
BS 5295 is a British Standard
British Standards (BS) are the standards produced by the BSI Group which is incorporated under a royal charter and which is formally designated as the national standards body (NSB) for the UK. The BSI Group produces British Standards under the a ...
.
BS 5295 Class 1 also requires that the greatest particle present in any sample can not exceed 5 μm. BS 5295 has been superseded, withdrawn since the year 2007 and replaced with "BS EN ISO 14644-6:2007".
USP <800> Standards
USP 800 is a United States standard developed by the United States Pharmacopeial Convention (USP) with an effective date of December 1, 2019.
Ramifications and further applications
In hospital
A hospital is a health care institution providing patient treatment with specialized health science and auxiliary healthcare staff and medical equipment. The best-known type of hospital is the general hospital, which typically has an emerge ...
s, theatre
Theatre or theater is a collaborative form of performing art that uses live performers, usually actors or actresses, to present the experience of a real or imagined event before a live audience in a specific place, often a stage. The perform ...
s are similar to cleanrooms for surgical patients' operations with incisions to prevent any infections for the patient.
In another case, severely immunocompromised patients sometimes have to be held in prolonged isolation from their surroundings, for fear of infection. At the extreme, this necessitates a cleanroom environment. The same is the case for patients carrying airborne infectious diseases, only they are handled at negative, not positive pressure.
In exobiology
Astrobiology, and the related field of exobiology, is an interdisciplinary scientific field that studies the origins, early evolution, distribution, and future of life in the universe. Astrobiology is the multidisciplinary field that investig ...
when we seek out contact with other planets, there is a biological hazard both ways: we must not contaminate any sample return missions from other stellar bodies with terrestrial microbes, and we must not contaminate possible other ecosystems existing in other planets. Thus, even by international law, any probes we send to outer space
Outer space, commonly shortened to space, is the expanse that exists beyond Earth and its atmosphere and between celestial bodies. Outer space is not completely empty—it is a near-perfect vacuum containing a low density of particles, pred ...
must be sterile, and so to be handled in cleanroom conditions.
Since larger cleanrooms are very sensitive controlled environments, within which multibillion dollar industry can take place, sometimes they are even fitted with numerous seismic base isolation
Seismic base isolation, also known as base isolation, or base isolation system, is one of the most popular means of protecting a structure against earthquake forces. It is a collection of structural elements which should substantially decoup ...
systems to prevent costly equipment malfunction.
See also
* Air ionizer
An air ioniser (or negative ion generator or Chizhevsky's chandelier) is a device that uses high voltage to ionise (electrically charge) air molecules. Negative ions, or anions, are particles with one or more extra electrons, conferring a net ne ...
* Air quality index
An air quality index (AQI) is used by government agencies to communicate to the public how polluted the air currently is or how polluted it is forecast to become. AQI information is obtained by averaging readings from an air quality sensor, whi ...
* Contamination control
Contamination control is the generic term for all activities aiming to control the existence, growth and proliferation of contamination in certain areas. Contamination control may refer to the atmosphere as well as to surfaces, to particulate matte ...
* Data recovery lab
* Microfiltration
Microfiltration is a type of physical filtration process where a contaminated fluid is passed through a special pore-sized membrane filter to separate microorganisms and suspended particles from process liquid. It is commonly used in conjunction ...
* Pressure room (disambiguation) A pressure room may refer to:
* A positive pressure enclosure, which uses positive pressure to remove harmful substances from the enclosure
* A negative pressure room
Negative room pressure is an isolation technique used in hospitals and med ...
* Particle counter
A particle counter is used for monitoring and diagnosing particle contamination within specific clean media, including air, water and chemicals. Particle counters are used in a variety of applications in support of clean manufacturing practices, ...
* Pneumatic filter {{Unreferenced, date=March 2008
A pneumatic filter is a device which removes contaminants from a compressed air stream. This can be done using a number of different techniques, from using a "media" type that traps particulates, but allows air to p ...
* Secure environment
* Semiconductor device fabrication
Semiconductor device fabrication is the process used to manufacture semiconductor devices, typically integrated circuit (IC) chips such as modern computer processors, microcontrollers, and memory chips such as NAND flash and DRAM that are pres ...
References
External links
Cleanroom Wiki--The Global Society For Contamination Control (GSFCC)
The Secretariat to ISO/TC 209 Cleanrooms and associated controlled environments, the group of experts who negotiate all aspects of the 14644 standard
{{Authority control
Rooms
Semiconductor device fabrication
Filters
Telecommunications engineering