Developed seat sensor to help detect drunk drivers

Scientists have developed a system of sensors mounted on car seats to detect when the driver is reclining, heart rate or breathing changes.

The world already has several systems that use vehicle-mounted cameras to detect drunk drivers. However, the team at Japan's National Institute of Advanced Industrial Science and Technology believes that they are not always reliable, New Atlas reported on December 8. Their alternative is a sensor system integrated into the car seat.

Experiment with mounting the sensor system on a chair in the laboratory.

Camera-based drunk detection systems typically work in two ways. The first is an external camera used to detect unusual vehicle movements such as gliding between lanes or sudden changes in state. The second is an internal camera that tracks the driver's face and looks for expressions such as eyes closed or head bowed.

According to the team, both of these systems have certain limitations. The external camera may be obscured by mud or dust, while the internal camera works poorly in low light. Therefore, they developed a pressure sensor system mounted in the seat to monitor the driver's body movements more effectively.

The system includes a sensor on the back of the chair that can detect the heart rate and respiratory rate of the volunteers in the test. These factors change characteristically when the driver becomes lethargic. Two other sensors placed in the seat helped detect when volunteers were repeatedly leaning left or right, movements that could indicate the driver was dozing.

The sensors are made from a piezoelectric material, meaning that they generate an electric current when subjected to mechanical stress. Such materials are often unable to withstand high temperatures, while automotive electrical equipment requires this.

The team of experts solved this problem by clamping a current-detecting coaxial cable in a specially folded sheet of piezoelectric material. The material consists of a polyimide resin backing with a zinc oxide film on one side and colloidal silver coated on both sides. As a result, they obtained a sensor that can withstand temperatures up to 121 degrees Celsius.

The new study is published in the journal ACS Applied Electronic Materials. Scientists are planning to install the sensor system in real car seats and test it on the road.