Sensor detects carbon monoxide to avoid cases of CO poisoning
June 26, 2019
By Elton Alisson in São Carlos (Brazil) | Agência FAPESP – A sensor developed by Brazilian researchers affiliated with the Center for Development of Functional Materials (CDMF) can help avoid cases of carbon monoxide (CO) poisoning.
This kind of accident is common in many countries where gas heating is used, including Brazil. In Argentina, for example, 250 deaths and 2,000 cases of CO poisoning are reported each year. On May 22, 2019, six Brazilian tourists were found dead in a rented apartment in Santiago, the capital of Chile. The medical examiner confirmed CO poisoning as the cause of death.
The sensor was presented to a Symposium on Research and Innovation in Functional Materials held on May 24 by CDMF, one of the Research, Innovation and Dissemination Centers (RIDCs) funded by FAPESP. The event took place in São Carlos (São Paulo State, Brazil), at the Federal University of São Carlos (UFSCar).
At the time of the symposium, Argentina’s National Congress was due to vote on a bill that would make inclusion of the sensor mandatory for all domestic gas heaters. In a letter sent to FAPESP President Marco Antonio Zago, Argentinian congressmen Eduardo Bucca and Fernanda Raverta, who drafted the bill, stressed the importance of such legal measures to combat CO poisoning and thanked FAPESP for its support.
“The sensor can also help avoid deaths from the inhalation of carbon monoxide in neighboring countries like Brazil, where this kind of accident is reported mainly in the South region and more recently in the Northeast, owing to the use of gas heaters,” Elson Longo, Executive Director of CDMF, told Agência FAPESP. Longo is a professor at UFSCar and one of the creators of the sensor. In addition to UFSCar, other participants in the project included researchers at São Paulo State University (UNESP) in Guaratinguetá, Argentina’s National University of Mar del Plata, Spain’s Jaime I University, and the University of Ferrara in Italy.
The device consists of a chip-sized integrated circuit with two electronic sensors, one to detect CO and the other to detect methane.
The sensors developed and patented by researchers contain nanometric layers of semiconducting oxides such as cerium oxide. Their resistance changes when they come into contact with CO and other gases. The electronic circuit interprets the change as a signal to shut off the gas supply to the heater.
“CO is produced by incomplete combustion of natural gas owing to a poor supply of oxygen. When the sensor detects CO levels higher than the safety limit, it cuts off the flow of natural gas to the burner,” explained Miguel Adolfo Ponce, a professor at University of Mar del Plata and one of the designers of the device.
Exposure to CO at levels up to 0.02 ppm (parts per million) is not a health hazard. Perceptible symptoms resulting from exposure to higher levels include drowsiness and headache. Exposure to 1,400 ppm for one hour can lead to death.
CO is hard to detect in everyday locations for a number of reasons. It is colorless, tasteless and odorless. Initially, it does not cause irritation of the skin, eyes and other mucous membranes. The only way to determine if it is present is the burner flame test, Ponce said: the flame is blue if there is sufficient oxygen at the burner to consume all the carbon in the natural gas; a yellow flame means the oxygen is insufficient and the carbon is becoming incandescent.
The gas appliances that cause the most domestic accidents due to CO poisoning are water heaters (87% of all such accidents), radiators (8%) and cookers (5%), according to Ponce.
“The system we’ve developed can easily be installed on these gas-burning appliances both in homes and commercial facilities,” he said.
The device has generated two patents and drawn attention from two companies that plan to produce it jointly, one Argentinian and the other Brazilian.
The researchers used this technology as a basis for developing a different sensor that can be coupled to a smartphone to detect the presence of CO not only from a change in electrical resistance but also using color. An app running on the phone sounds the alarm.
“It’s a monitoring system that can be used in mines, where death from CO poisoning is not uncommon,” Longo said.
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