BIOSENSORS: TYPES

Medical Telesensor chip: a “medical telesensor ASIC.” 2x2-millimeter silicon chip. Powered by a lithium battery. Attached using a nonirritating adhesive. Can measure blood pressure, oxygen level, and pulse rate.

Microcantilever: an alternative to optical fiber. Is approximately 100mm long , 30mm wide, and 3-4mm thick. Detects change thru bending or change in vibrational frequency, which can be seen when a light beam hits it and is deflected by it. Depending on the surface coating of the planks and the materials attached to the ends of them, it can measure temperature, viscosity, density, flow rate, and the presence of proteins in solution (bacteria and viruses). The volume necessary is 1ml.

Bioreporters: also called “critters on a chip.” Genetically engineered bacteria secrete light-emitting proteins when metabolising their chemical-specific diets. No oxygen is required for the light emission. Most useful during chemical spill cleanup.

Luminescence spectrometer: can be used to detect bacteria and other microorganisms. They release small amounts of adensosine triphosphate (ATP), which in the presence of oxygen is converted to light energy by luciferase. The intensity of the light would determine the concentration of the organisms in the water.

Infrared microspectrometer: carved out of a 1.5x1.5x1.5cm3 plastic cube and has no moving parts. Analyses by exciting certain chemicals with a light source. The excited compounds give off various lengths of infrared light. The light is channeled into an optical fiber for analysis and the wavelengths are sent to a microchip to identify and determine the concentration of the chemicals in the sample. The device is inexpensive and has a variety of uses.

Mass spectrometry: According to Oak Ridge National Laboratory (ORNL), bacteria have unique chemical patterns in their lipids, and therefore, can be identified thru this technique. There are two methods for mass spectrometry, either by
1. extracting the lipids thru solvents, or
2. illuminating airborne bacteria with laser light to obtain a mass spectrum. U.S. Military organizations are trying to reduce the time of this technique to less than five minutes to detect biological hazards on the field.