is an invisible odorless gas that is the leading cause of accidental poisoning deaths in America. Carbon monoxide detectors can alert you to dangerous levels of carbon monoxide.
How the First Carbon Monoxide Detectors Worked
Originally, carbon monoxide detectors were simple opto-chemical detectors that indicated the presence of carbon monoxide by exhibiting a color change when carbon monoxide reacted with a chemical on a white pad, producing a brownish or black color. These detectors do not require an external power source to function, but modern designs use audible alarms to confer a higher level of protection:
Biomimetic Carbon Monoxide Sensors
A opto-chemical or gel sensor interacts with synthetic hemoglobin, darkening in color when carbon monoxide is present and lightening in color when carbon monoxide concentrations are low. A light sensor may be used to detect the change in light levels to sound an alarm.
Semiconductor Carbon Monoxide Detectors
An integrated circuit monitors a sensor, tripping the alarm when concentrations of carbon monoxide are high. The sensor is made from thin wires of semiconducting tin dioxide that rest on an insulating ceramic base. Increasing carbon monoxide concentration reduces the electrical resistance of the sensor, causing the alarm to sound.
Electrochemical Carbon Monoxide Detectors
This is an electrochemical cell that is designed to produce current in relation to the amount of carbon monoxide present in the air. Carbon monoxide is oxidized to carbon dioxide at one electrode while oxygen is consumed at the other electrode. Sulfuric acid is the usual electrolyte that separates the electrodes. The current triggers the alarm or can even be used to quantify the amount of carbon monoxide that is present.