Digital breathalyzers are the most widely used method for finding out how high the concentration of alcohol in a person’s blood is.
It does not matter if you are a policeman or a private person, or if you run a business where driving a car is a crucial element. Everyone can benefit from alcohol testers.
The small measuring instruments are so popular because they can be used over and over again, and the results are incredibly reliable. Of course, this only applies if you use a high-quality device.
High-quality breathalyzers are based on electrochemical sensors that deliver reliable results. In contrast, low-quality alcohol testers often only use semiconductor sensors that are significantly less precise.
The essential facts shortly
- Electrochemical sensors determine the alcohol content
- Reliable breathalyzers are accurate to +/- 0.05 per thousand
- Every twelve months, the device should be calibrated
- Quality stands and falls with the price
- Secure methods are available from $100,00
How does the alcohol test work with a digital device?
First of all, the person to be tested has to blow into the mouthpiece of the alcohol tester for a few seconds. When the beep is sound, enough breathing air has been pumped into the unit so that the breathalyzer can work properly.
Now part of the breathed breathing air is led into the reaction chamber. In this are the measuring electrode, the counter electrode, and a certain amount of electrolytes.
- At the measuring electrode, the ethanol, which has entered the device through the breathing air, is oxidized and thus converted into electrical energy. Say: The ethanol releases its electrons during the reaction.
- Oxygen is withdrawn from the counter electrode so that an electrode current arises between the measuring and counter electrode. At this point, the measurement starts.
- Now the current flow is measured over a specified period, and the size of the electrical charge is determined.
Simply put, the more alcohol in the breath, the more electrons flow to the counter electrode during the reaction — accordingly, the per thousand-value increases, which comes out at the end as a result.
Finally, the results are amplified, digitized, and converted into blood values using a small computer. The final result is then shown on display, and you know how much you have drunk and if you are still fit to drive.
But beware: alcohol affects each person differently. Some experienced drunkards might be even better with a lot of alcohol in their blood than someone who has drunk significantly less. Anyone who is not sure that he can operate a motor vehicle should leave the car.
The relationship between alcohol in the blood and exhaled air
As you know, the goal of blood alcohol controls is to understand the levels of alcohol present in the blood. Still, because it is an invasive test, slow and complicated logistics to perform it smoothly on the road, the best is the use of the famous breathalyzers, which can analyze blood alcohol levels through their correlation with exhaled air, which contains vaporized ethanol that passes to the pulmonary alveoli during the metabolization process.
In this way, if the maximum allowed blood alcohol level in Spain is 0.3 g / l for professional and novice drivers and 0.5 g / l for all others, this is extrapolated to 0.15 mg / l. L of exhaled air for the former and 0’25 mg / l for the latter.
How are alcohol levels measured with the breathalyzer?
The methods used by the breathalyzer to measure the levels of alcohol in exhaled air are mainly two:
Through an infrared sensor
The infrared-based method is based on the property of the gases to absorb part of the electromagnetic radiation that passes through them.
Focusing on the case of infrared, located within the spectrum between the visible area and microwaves, the length absorbed most efficiently by vaporized ethanol is 9.5 micrometers, so the technique used in the breathalyzer consists of the use of an infrared emitter coupled to filters that will eliminate all the waves that are not at 9.5 micrometers, to avoid false negatives.
In this way, when the desired waves pass through the exhaled air by the conductor being tested, the energy that is not absorbed will be transformed into electrical power, whose levels will be extrapolated to the amount of ethanol in the air, the minimum possible energy should be lost.
Through an electrochemical cell
The method of the infrared sensor is quite expensive, so over the years, it has become necessary to change the way used by another less expensive method, such as electrochemical cells, which are devices capable of obtaining electrical energy through the use of chemical reactions.
One of the best known electrochemical cells is the cell, which, as you know, consists of two metal electrodes (the cathode and the anode) introduced into a solution known as an electrolyte.
By introducing the electrodes into the electrolyte, an oxidation reaction occurs at the anode, which will lead to an electron flow that will travel to the cathode, which will be reduced (the reverse reaction to oxidation) leading to an electric current.
Although it is not the same, the reaction produced in this type of breathalyzers is very similar, since the exhaled air passes to the anode, where the ethanol is oxidized giving rise to acetic acid and generating an electric current that will be proportional to the amount of ethanol present in the air.
Not chewing gum, or drinking coffee, or sucking the battery of a cell phone (yes, there is someone who defends this technique) will make you mock any of these methods, but what it will do is that you take the car only if you are sure that enough time has passed since you drank so that the alcohol is completely metabolized.
Quality of digital alcohol testers
Digital breathalyzers are a handy thing. When buying such a meter, however, one must bear in mind that there are qualitatively vast differences between the individual devices. If you want to buy a reliable tool that delivers police-accurate results, we should put in our experience at least $100.00 on the table.