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Automotive - CO2 and alcohol sensors

Sensors are the crucial sensory organs of vehicle safety systems. Measuring gas in the automotive industry has various benefits: by detecting ethanol on the driver's breath, drunk driving can be prevented, and by controlling the air quality in cabins, not only is the risk of drowsiness reduced, but it also contributes to a positive environmental impact.

For decades, we've been developing world-leading NDIR CO2 sensors. We're in the centre of excellence and our sensors can be placed not only in normal indoor applications but also in vehicles. Our Automotive sensor contains electronics with no moving parts, which makes it robust and resistant to vibrations.

Ten years ago, we started developing an "impossible" alcohol sensor funded by the US Road Administration and major car manufacturers - a sensor that is more or less invisible in the vehicle, but that automatically detects if the driver is in condition to drive. Today, the third generation of alcohol sensors is on the market (Senseair Safe Start), and the fourth generation is being tested in cars on roads in the US right now.

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Alcohol sensors in cars

In the field of automotive alcohol safety systems, we enjoy close co-operation with Autoliv, a leading global supplier of those kinds of systems. Our current projects include the development of a new technology to allow for contact-free, unobtrusive measurement of the driver’s breath alcohol.

When it comes to measuring a person’s blood alcohol concentration, most people are familiar with breathalysers that require that drivers provide a deep lung sample by blowing into a tube or other sensor. In contrast, the breath-based system being developed by Senseair and Autoliv Development is designed to unobtrusively analyse alcohol on the driver’s breath. Drivers will simply be able to enter the vehicle and breathe as they normally would. 

Key Benefits:

  • Contact-free
  • Unobtrusive
  • No calibration required
  • Measures alcohol as the driver breathes normally while seated in the driver's seat

How does it work?

The system draws the driver’s exhaled breath into a sensor, which measures the concentrations of alcohol and carbon dioxide present. The known quantity of carbon dioxide in human breath serves as an indicator of the degree of dilution of the alcohol concentration in exhaled air.

Molecules of alcohol and tracers such as carbon dioxide absorb infrared light at specific wavelengths. The Senseair device directs infrared light beams on the breath sample and analyses the wavelengths returned in order to quickly and accurately calculate the alcohol concentration.

We have already implemented one touch-free unit, but we continue to move towards a prototype that can be integrated into the dashboard of a vehicle by utilising mirrors to reduce the required optical length of the device. The device is highly sensitive and able to analyse diluted breath samples at dilutions expected from a driver’s natural breath plume.

Testing the prototype

To test the prototype under development, the DADSS Research Program has developed a wet gas breath simulator. The simulator blends gases such as carbon dioxide, nitrogen, and oxygen with moisture to create an “exhaled breath” that matches the composition, temperature, and pressure of natural human breath. Ethanol can then be added to the breath at various concentrations. In addition, the Senseair prototype will continue to run through a series of tests with human subjects, as well as durability tests in different environmental situations, from temperature shifts to sudden changes in motion, and interference (e.g. dust or mechanical shock).

Read more about the project at https://www.dadss.org/breath-based-technology/

Measure CO2 with our sensors for cabin safety & comfort

Because humans exhale carbon dioxide, a cabin full of people can quickly reach a high level of CO2. This can lead to drowsiness that we do not notice until we experience physical symptoms. The same problem occurs in other vehicles, like trains, buses, and aeroplanes. Of course, you could ventilate at full speed all the time, but that is neither comfortable nor an energy efficient option. With CO2 monitoring, you can measure the exact amount of ventilation you need to keep the cabin climate at the optimal level. 

Key Benefits:

  • Healthy cabin air
  • Energy savings
  • Positive environmental impact
  • Reduced risk for driver drowsiness

Why measure CO2 in cabins?

Cars, subway trains, and aeroplane cabins are becoming increasingly well-sealed. The CO2 concentration in a vehicle varies depending on the number of people in it. For example, the concentration in a fully occupied cabin, compared to an empty cabin, can quickly become critical. Therefore, we have to ventilate.

High levels of CO2 can cause tiredness and a lack of concentration, which can be dangerous. In the case of a driver falling asleep, the situation quickly becomes serious. It is also necessary to ventilate to ensure a healthy indoor environment in vehicles. Even small cabins can hold many people per m3. Bad air quality also increases the likelihood of catching viruses, bacteria, and other small particulates.

Freon gas and ammonia are the most frequently used refrigerant systems - particularly in cars. However, CO2 is becoming favoured as it is non-combustible and is much less harmful to the environment. Of course, any gas leak needs to be detected quickly. 

How does it work?

An empty vehicle has a carbon dioxide concentration of about 400 ppm (normal outdoor concentration). The CO2 concentration in the car, aeroplane, subway, or train will increase for each person added. Therefore, using a Demand Controlled Ventilation system is the best choice for high efficiency. Demand Controlled Ventilation means that sensors are measuring the CO2 value constantly and sending a signal to the ventilation system that changes the level of the ventilation to compensate. 

Reduced costs

Thanks to the reduced need for constant ventilation, a Demand Controlled Ventilation system helps vehicle save energy. Engineers calculate fuel savings of up to 10%. This is both a financial and environmental saving.

Demand Controlled Ventilation also saves society money based on not having to send people to hospitals for cases of CO2 poisoning or other air quality-related illnesses. Fewer traffic accidents caused by drowsiness also reduces the damage caused to people, roads, buildings, etc. 

If you wish to read more on the subject, click here for a paper by Indira Gurubhagavatula.

Forgot someone in the car?

Every year, both children and pets die after being left or forgotten in the car for too long. With a Climate Control System that measures CO2, the car can detect if someone is breathing in the vehicle and thus starts the ventilation/AC. CO2 monitoring is a form of life insurance. If you would like to know more about the subject, please click here to download the brochure.

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