Biosensors were invented in 1967, with the glucose sensor being the first. The glucose sensor was developed to measure blood glucose levels in diabetics and utilizes the enzyme glucooxidase. By selecting only glucose from the blood and reacting with it, blood glucose levels could be measured quickly and accurately. Since then, biosensors utilizing various enzymes and microorganisms have been devised and have begun to be put to practical use in the food and medical fields. Currently, the domestic market for biosensors has grown to tens of billions of yen, mainly in the medical field.

Biosensors were invented in 1967, with the glucose sensor being the first. The glucose sensor was developed to measure blood glucose levels in diabetics and utilizes the enzyme glucooxidase. By selecting only glucose from the blood and reacting with it, blood glucose levels could be measured quickly and accurately. Since then, biosensors utilizing various enzymes and microorganisms have been devised and have begun to be put to practical use in the food and medical fields. Currently, the domestic market for biosensors has grown to tens of billions of yen, mainly in the medical field.

There has also been a movement from the beginning to apply these biosensors to the environmental field. The first practical application was the BOD sensor commercialized by Nissin Electric as the world's first environmental measurement biosensor. This sensor uses microorganisms as receptors, and when the microorganisms take in water pollutants, their respiration rate increases, and as a result, the oxygen concentration in the surrounding environment changes. This method has shortened the measurement time from several minutes to about one hour, compared to the five days it used to take in the past, and has made it possible to measure in near real time. Currently, this sensor is widely used to check water quality in factory wastewater and sewage treatment facilities, and accounts for about 90% of the domestic market share.

The basic mechanism of biosensors is that a "discriminating element" (receptor) made of biological material captures the target substance and the resulting response (emission of light by fluorescence or generation of electric current) is captured as a signal to determine the amount and concentration of the measured substance. Biosensors are classified according to the type of receptor. The main types are enzyme sensors, which use enzymes that react to specific substances; immunosensors, which use antibodies to capture pathogens that have entered the body; and microbial sensors, which use the reaction of contaminants when they are taken into the cells of microorganisms.

Chemical analysis methods, which are currently the mainstream, determine contaminants by repeating the process of removing various components from samples taken from the air, water, and soil. Therefore, it is not unusual for a single sample to take more than five days to analyze. In particular, measuring trace amounts of substances such as dioxins and environmental hormones can take two weeks or more. Furthermore, analytical technicians need to be highly skilled, and human resource development has not kept pace with the rapid increase in measurement and analysis needs in recent years. To remedy these problems, the development of biosensors is accelerating.

The advantages of biosensors include the fact that they do not require complex pretreatment, are highly selective, and can make measurements in a short time (several minutes to several dozen minutes) with a small amount of sample. In addition, data handling is easy because the output can be extracted as electrical or optical signals. On the other hand, there are some disadvantages, such as short life span of the bioelement, narrow measurement range, and fluctuations in the activity of biological substances.

Currently, research is underway to commercialize biosensors for measuring dioxins and environmental hormones, and actual products may be on the market in as early as two to three years. For example, Enbiotech Laboratories is developing biosensors that utilize the immune system of living organisms in collaboration with several universities. In addition, the University of Tokyo's International and Industry-Academia Joint Research Center is developing a biosensor that can measure extremely small amounts of dioxin using antibodies to dioxin produced in the bodies of mice.

Two elements are important in the development of biosensors: receptors and signalization technology. Since it is difficult to create antibodies against highly toxic substances such as dioxins using conventional methods of creating receptors, peptide- and DNA-based receptors are being studied as a new method. This will make it possible to measure trace amounts of substances with high precision.

Although biosensors have some issues such as cost and difficulty in maintenance compared to chemical analysis methods, they are expected to be a new business opportunity due to their accuracy and speed.