BIOSENSOR

Biosensor

Biosensor

Introduction

A biosensor is a device that uses a biological reaction for detecting substances in the environment. To accomplish this, biosensors contain either whole bacterial cells or a component of bacterial cells, usually enzyme systems. Biosensors detect, within minutes, or even seconds, chemical and biological compounds in the environment. Quick response and sensitivity to very small concentrations of compounds make biosensors an attractive tool in pathogen detection, in foods and water, and as a warning system against biological weapons (Lowe, 1984, 59-64).

Medical biosensors have been developed to detect small changes in a person's physiology for the purpose of detecting disease, such as certain blood proteins that may indicate the presence of a cancerous tumor. Environmental biosensors detect chemicals or biological agents in the environment. These sensors help scientists to monitor the presence of hazardous chemical pollutants and of biological pollution from wastes and wastewater or, most recently, to detect of bioweapons in the environment. Current biosensor technology involves devices that detect, record, and transmit information (Russell & Rawson, 1986, 301-318).

Scientists developed the first biosensors for practical uses, in the 1980s, at the time when biotechnology was rapidly discovering new ways to use individual cell components or even genes. For example, scientists at the Oak Ridge National Laboratory (ORNL), in Tennessee, developed biosensors to detect cancer-causing chemicals in underground sources of drinking water. The ORNL biosensor contained a fiber-optic piece linked to an antibody developed specifically to detect the carcinogen benzene(a)pyrene. As soon as the antibody finds and binds to the target chemical, the light portion of the biosensor causes the emission of fluorescent light. The fiber-optic component detects the fluorescence and sends a signal up the fiber to a monitor. Because the telesensor uses light as its mode of carrying information, it is also referred to as an optical biosensor. This biosensor won for ORNL the 1987 Research and Development 100 Award (Turner, 1987, 259-270).

Biosensor technology has since expanded into added detection systems for a greater number of chemicals and biological substances. The latest medical biosensors are sometimes called telesensors; they are silicon chips measuring about 2 by 2 millimeters (mm). Telesensors placed on the skin can measure body temperature, pulse rate, and various changes in the body's physiology. As all biosensors do, telesensors offer the valuable advantage of providing this information as it occurs (Kricka & Thorpe, 1986, 253-258). Biosensors shorten the time that physicians and environmental scientists spend in detecting chemicals in patients or the environment, respectively.

An industry called bioelectronics has grown, in the past decade, with the goal of inventing more sensitive and molecule-specific biosensors. In addition to an expanding list of medical uses, the following industries use biosensors: breweries, food production, hazardous site monitoring, wastewater treatment, and water quality testing. Bioelectronics engineers work on improving current biosensors to make them more sensitive, durable, stable, and portable (Lowe, 1984, 59-64).

Components of Biosensors

Biosensors are of two types: whole cell and cell component. Each type contains two parts; one is called the sensor and the other are the ...