Carbon monoxide sensor can prevent poisoning deaths

In this illustration, the CO sensor is the blue button on the top that powers the gas flow cutter switch (bottom right) of the heater. [Image: CDMF]

Legal sensor

A sensor developed in Brazil has aroused the interest of Argentine authorities and is now close to becoming a mandatory security item in that country.

"The sensor can help prevent deaths by inhalation of carbon monoxide in both neighboring countries and Brazil, where this type of accident is recorded mainly in the South region and more recently in the Northeast due to the use of gas heating, explained Professor Elson Longo, director of the CDMF (Center for the Development of Functional Materials).

Carbon monoxide (CO) poisoning is the most likely cause of the deaths of six Brazilian tourists in Chile last week. This type of accident is common where gas heating is used. In Argentina, for example, there are 250 deaths and 2,000 cases of toxic gas intoxication every year.

Carbon monoxide sensor for heaters

The device consists of an integrated circuit equipped with an electronic sensor of CO (carbon monoxide) and another of methane, developed and patented by the team of the CDMF, that also has already developed sensors of ozone, hydrogen and ionizing radiation .

The sensors are made up of semiconductor oxides, mainly cerium, on the nanometer scale (of the billionth part of the meter). In contact with CO and other gases, these oxides exhibit a change in electrical resistance, which is processed and interpreted by the electronic circuit as a signal to stop the flow of gas in the equipment in which the system is installed, such as a water heater.

"Carbon monoxide is produced by the incomplete combustion of natural gas because of the lack of oxygen in the environment, so by detecting the presence of CO above the safety limit, the sensor cuts the flow of natural gas to the burner," explained Miguel Adolfo Ponce, one of the creators of the project.

According to the researcher, exposure to a concentration of 0.02 parts per million (ppm) of CO does not cause harmful effects to health. Above that level begins to cause noticeable symptoms such as drowsiness and headache. Exposure to 1,400 ppm CO for one hour is likely to lead to death.

Some factors make it difficult to detect CO in the environment. The gas is colorless, tasteless, odorless and does not irritate the mucous membranes. The only way to perceive it is by the color of the burner flame - if it is not bluish, characteristic of the complete combustion of natural gas by the correct amount of oxygen, can be an indication of CO emission, Ponce said.

Version of the carbon monoxide sensor to be used portable, in mines and other industrial facilities. [Image: CDMF]

Sensor coupled to the cell phone

The device has already generated two patents and aroused the interest of an Argentine company and a Brazilian company, willing to manufacture it together.

Based on this technology, researchers have developed another type of sensor that can be coupled to a cell phone and is able to detect and indicate the presence of CO not only by changing the electrical resistance, but also by color, and indicate the danger through of an application.

"This monitoring system can be used in mines, where deaths from carbon monoxide poisoning are also recorded," Longo said.