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- The World First -MEMS Gas Sensors Adopted!
- User Calibration provides Higher Accuracy & Reliability!
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 Fuel
Cell gas sensor type : This type of sensor is mainly used
in evidential devices for Police Dept.
This is professional device with higher cost accordingly(more
than USD 1,000)
Semiconductor
Gas Sensor type : It is sold in the market for general
public use and police uses it to check whether a person's
alcohol level is more than legal limit or not. This product
has advantages of quick reaction speed and cheap price
but its accuracy is not as accurate as Fuel Cell type.
Our product is Semiconductor Gas Sensor type.
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When sensor is exposed to alcohol,
electric resistance of the sensor drops. Using this principle,
the concentration of alcohol is obtained by calculating the
reduced electric resistance.
Ex) When electric resistance of a sensor is 10㏀ and the
sensor is exposed to 0.05% alcohol, electric resistance
of the sensor drops to 5㏀. This is stored in the memory
of the sensor, and when the sensor measures unknown alcohol
(from the person who had drinks), the sensor displays
0.05% if electric resistance of the sensor drops to 5㏀.
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As gas sensor is a kind of chemical sensor which is
easily affected by humidity and temperature, tolerance
is quite significant depending on season. Graph for the
seasonal tolerance is as follows:
In the above figure, when the electric resistance
of a sensor was affected by humidity and temperature and
is changed (namely, in case the resistance was moved to
ⓐ or ⓑ), existing Alcohol Detector should go back to factory
for re-calibration. However, in reality, re-calibration
of all the sensors in the factory is practically impossible
and therefore people use the sensor as it is even though
the sensor is wrong.
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Seju’s Alcohol Detector is equipped with calibration
function in itself. When sensor electric resistance was moved to
ⓐ or ⓑ in the above figure, the microcontroller of Seju’s Alcohol Detector
detects the change in electric resistance and calculates the difference
and the sensor displays accurate density.
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Power
Source : 2 AAA Size Battery