Biosensors and Microarrays

Biosensors, microarrays, biochips and lab-on-chip (LOC) products are microscale devices for biological, biochemical and chemical assays. They consist of microfluidic channels and a biodetector or microsensor arrays. There are many different types of biosensors and microarrays. Choices include biohazard detectors, environmental detectors, hazardous material detectors, chemical warfare agent (CWA) detectors, and biological warfare agent (BWA) detectors. Biohazard, environmental, and hazardous material (HAZMAT) sensors are used in various commercial, industrial and regulatory applications. In the United States, CWA sensors and BWA sensors are used by the Department of Defense (DoD), the Department of Homeland Security (DHS), and other federal, state and local agencies. Specialized biosensors, microarrays, biochips and LOCs are also available.

Biosensors and microarrays include simple devices called microassays on card (MAC). These portable, handheld, immunoassays are designed to test samples for environmental toxins or illegal substances. First, a small quantity of test solution is placed on one side of the MAC. The color that develops on the other side of the card is directly proportional to the toxin in the test solution. Biosensors and microarrays such as MACs are self-regulating so that operating timing and the introduction of reagents are not required. Devices that are designed to simultaneously test multiple species have two or more wells and may feature a nanogram-per-milliliter sensitivity.

Biosensors and microarrays that meet U.S. military specifications (MIL-SPEC) are used to detect both chemical warfare agents (CWA) and biowarfare agents (BWA). The U.S. Army Center for Health Promotion and Preventive Medicine (USACHPPM) publishes several standards for airborne exposure limits (AEL): immediate danger to life/health (IDLH), short-term exposure limit (STEL), worker population limit (WPL) and general population limit (GPL). USACHPPM also defines acute exposure guideline levels (AEGL) for airborne chemical warfare agents such as nerve gas and sarin. Biosensors and microarrays are also used in BWA detection and other homeland security applications. These sensors are designed to identify specific biological warfare agents such as bacillus anthracis, francisella tularensis, yersinia pestis, or butulotoxin.

Biosensors and microarrays carry product specifications such as integrated circuit (IC) package type. Choices may include SC-170, which is used in handheld devices such as cellular phones and personal digital assistants (PDAs); small outline transistor (SOT) packages such as SOT23 and SOT123; small outline (SO) packages such as SO-8 and SO-16; and various transistor outline (TO) packages. Bare die and quarter size outline package (QSOP) products are also available. Some biosensors and microarrays also interface with bus types such as the system management bus (SMBus), the industry standard architecture (ISA) bus, the I2C bus, and the actuator sensor interface (AS-I, ASi).

• Rapid Microbiological Methods for a New Generation
  By Michael J. Miller, Ph.D., Senior Research Fellow, Eli Lilly and Co. Microarrays are collections of miniaturized test sites, arranged on solid substrates, that permit many tests to be performed at...
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• Rapid Microbiological Methods for a New Generation
  By Michael J. Miller, Ph.D., Senior Research Fellow, Eli Lilly and Co. use viability stains and/or cellular markers to detect and quantify microorganisms without the need for cellular growth....
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