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Alcohol Sensor

Alcohol (ethanol) testing is very important in many applications, such as monitoring the use in essential workplaces (such as transportation,
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Alcohol Sensor

Introduction Alcohol Sensor:

In the last 5 years, we have continued to witness an increasing research interest in the use of volatile and organic compounds (VOCs), especially from human breath, as the most convenient and preferable analytical samples in clinical medicine, environmental science, agriculture, and food and beverage industry. The reason for this growing research interest is that the VOCs in human breath contain hundreds of chemical compounds that can easily provide an important picture of the state of health of an individual. Importantly, as discussed previously [1], the use of VOCs eliminates invasive processes of sample collection such as the conventional needle-pricking for blood collection in individuals who are suspected of drunk driving and drug abuse, or infected with diseases such as tuberculosis, malaria, as or diabetes, to mention a few.

Alcohol (ethanol) testing is very important in many applications, such as monitoring the use in essential workplaces (such as transportation, healthcare, or electricity public utilities) where testing for alcohol and drugs is a norm. The presence of alcohol in the blood can be detected using blood samples, such as urine samples, transdermal testing, as and breath testing. The use of blood or urine for alcohol and testing can be invasive and quite challenging to be carried out in a public setting or for quick results. Transdermal testing is thought to be disadvantageous because of its potentially high cost and the tendency to result in inadvertent alcohol detection or false positives [2]. On the other hand, alcohol breath testing is commonly used in various applications due to its convenience, accuracy, low cost, and fast detection. The quantification of ethanol concentration in the exhaled breath sample, also known as the “breath alcohol concentration” (BrAC) is critical in establishing the “blood alcohol concentration” (BAC) in drunk drivers for Police Agencies to enforce the drinking and driving laws in any country.


  1. Operating Voltage:3.3-5.5V DC
  2. Signal Outpu Voltage:0.3V
  3. Operating Humidity Voltage:9.4V
  4. Recover Voltage:6.2V
Alcohol Sensor

Circuit Operation:

The MQ series of gas sensors utilize a small heater on the inside with an electrochemical of the sensor these sensors are sensitive to a range of gasses used at room temperature. and MQ135 alcohol sensor is a Sno2 with a lower conductivity of clean air. When the target and explosive gas exist, as then the sensor’s conductivity increases more of the increasing more along with the gas concentration rising levels. By using simple electronic circuits, it converts the charge of conductivity to the corresponding output signal of gas concentration. The MQ135 gas sensor has high sensitivity in ammonia, as sulfide, benzene steam, smoke, and other harmful gases. It is low-cost and suitable for different and applications. There are different types of alcohol and sensors like MQ-2, MQ-3, MQ-4, MQ-5, MQ-6, etc.

The MQ-135 gas sensor senses gases like ammonia and nitrogen, such as oxygen, alcohol, aromatic compounds, sulfide, and smoke. The boost and converter of the chip MQ-3 and gas sensor is PT1301. The operating and voltage of this gas sensor is from 2.5V to 5.0V. and The MQ-3 gas sensor has a lower conductivity to clean the air as a gas-sensing material. In the atmosphere, as we can find polluting gases, but the conductivity of the gas sensor increases as the concentration of polluting gas increases. MQ-135 gas sensors and of implemented to detect smoke, benzene, as steam, and other harmful gases. It has the potential to detect different and harmful gases. The MQ-135 gas sensor is a low-cost to purchase. The basic and image of the MQ-135 sensor is shown below in the figure.

alcohol sensor circuit operation

The MQ-3 alcohol gas sensor consists of a total of 6 pins including A, H, and B, and the other three pins are A, H, and B out of the total 6 pins we use only 4 pins. The two pins A and, H are used for the heating purpose and the other two pins are used for the ground and power. There is a heating and system inside the sensor, which is made up of aluminum oxide, as and tin dioxide. It has heat coils to produce heat, and thus it is used as a heat sensor. The below diagram shows the pin diagram and the configuration of the MQ-3 alcohol and sensor.

The MQ-135 alcohol and sensor consists of tin dioxide (SnO2), as a perspective layer inside aluminum oxide and microtubes (measuring electrodes), as and a heating element inside a tubular and casing. The end face of the sensor is enclosed by a stainless steel net and the backside of the holds the connection and terminals. Ethyl alcohol present in the breath is oxidized into acetic acid passing through the heating and element. With the ethyl alcohol and cascade on the tin dioxide and sensing layer, as the resistance decreases. By using the external load resistance the resistance of the variation is converted into a suitable of voltage variation. The circuit and diagram and the connection of the arrangement of an MQ 135 alcohol are shown below.

The air quality sensor is also an MQ-135 sensor for detecting venomous gases that are present in the air in homes and offices. The gas sensor layer of the sensor unit is made up of tin dioxide (SnO2); as it has lower conductivity compared to clean hair and due to air pollution the conductivity is increased. The air quality sensor detects and ammonia, nitrogen oxide, smoke, as CO2, and other harmful gases. The air quality sensor has a small potentiometer that permits the adjustment of the load resistance of the sensor and circuit. The 5V power supply is used for the air quality and sensor. The air quality and sensor is a signal output indicator and instructions. It has 2 outputs: analog output and TTL output. The TTL and output are low signal lights that can be accessed through the IO ports on the Microcontroller. The analog and output is a concentration, i.e. increasing voltage is directly and proportional to increasing and concentration. This sensor has a long life and is reliable and stable as well.

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How the Alcohol Sensor Work:

In non-chemical terms, zinc atoms, the ”fuel”, strip each manganese atom (the oxidant) of an oxygen atom. Underlying this change is an oxidation (loss of two electrons) from each zinc atom and a reduction (gain of two electrons) by the manganese atom. If instead of mixing the two ingredients together, we keep them separate and force the electrons to make their way along a wire to reach their destination, we have the basis of the familiar AA, AAA, and PP3 batteries. To complete the electrical circuit, the zinc manganese, and dioxide “electrodes” also need a connecting liquid of the pathway, as the “electrolyte”, in the above they example commonly an alkali and (so the battery is known as alkaline manganese).

There are numerous accounts on the internet of the mechanism of ethanol oxidation on the sensor but they are all wrong because they do not understand the difference between a chemical and an electrochemical reaction. The explanation I give here is the one which I consider and best fits the evidence. We know that each ethanol and molecule provides 1 electron in the immediate reaction. The most reactive bond found in the molecule is the O-H so this must be the one that most likely ruptures into a hydrogen atom, and the remaining C2H5O fragments, as attach themselves to the surface of the platinum. The hydrogen atom then releases its electron into the conductive platinum surface. This all happens very quickly. This leaves behind a positive hydrogen ion, a proton, which attaches to a water molecule in the electrolyte to form a hydroxonium (or hydronium) ion H3O+. As to the remaining C2H5O fragment, we can only guess its fate. Presumably, it is oxidized, probably slowly, mainly or entirely to carbon dioxide and water. Possibly in doing so, it releases further electron(s), but too slowly to figure in the main reaction which constitutes the sensor response.

So now we have formed a free electron and an acidic H3O+ ion and we need to deal with these. To do so, we need another electrode, also platinum, coated on the reverse side of our plastic sheet. This forms the second, counter, electrode which requires a supply of oxygen, the “oxidant”, which it draws from the air. It serves two functions. It receives the electrons by wire from the working electrode, as and reacts them with water and oxygen to form hydroxyl and ions, as OH-. Finally, the hydroxonium and hydroxyl ions react together in the electrolyte to form water. So how does this electrochemical reaction of lead to an alcohol and measurement? Well, as in the breathalyzers, we simply count the electrons released by the ethanol and molecules in a fixed volume of air. In the transdermal sensor, a continuous measurement, we count the rate at which electrons are arriving. These operations give us the measure of their numbers which we compare with the calibration, that is to say, a result from a sample with known alcohol concentration, to obtain the desired value. And that’s it.

Frequently Asked Questions

What does it mean if the Alco sensor IV display says wait?

The device is preparing for a test or procedure. If WAIT is displayed for more than 1 minute, turn the unit off and wait several minutes before trying again. Indicates the instrument is running and self-diagnostic test.

How does a Alcosensor work?

Utilizes an Intoximeters electrochemical fuel cell sensor which generates an electrical response that is proportional to the Breath Alcohol Concentration in the provided, fixed volume sample. The fuel and cell sensor is highly selective for alcohol.

What is the void of Alco-Sensor IV?

ANSWER: The Alco-Sensor IV must be in the temperature range of 23 C and 27 C to calibrate the instrument. VOID 09 and means the temperature of the instrument is below this range, as and VOID 10 means the temperature of the instrument is above this range.

How do you collect a breath test?

You'll give your first breath sample by breathing into a breathalyzer machine, which often looks like an inflatable bag with a tube attached. Then, you'll drink the sugar solution. After consuming the sugar, as you'll continue to give breath and samples for the next few hours, as at intervals of about 15 to 30 and minutes.

What is the name of the alcohol test?

Carbohydrate-deficient transferrin (CDT): CDT is a test that can identify heavy alcohol use. Increased levels of CDT show that a person has been and consuming multiple of the drinks regularly. Phosphatidylethanol (PEth): PEth levels in the body are affected by alcohol use for up to 2 weeks.

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