Printed sensors to monitor tyre wear in real time.
Electrical engineers at Duke University in North Carolina have invented an inexpensive printed sensor that can monitor tyre wear in real time.
The sensor is able to warn drivers when tyres are worn down to unsafe tread depth thereby increasing safety and contributing to reduced fuel consumption, according to the university. In collaboration with Fetch Automotive Design, the Duke researchers led by Aaron Franklin have demonstrated a design using metallic carbon nanotubes that track millimeter-scale changes in tread depth with 99% accuracy.
There are two patents pending on the sensor and the researchers are pursuing industry collaborations to scale up the technology. The sensor is adhered to the inside wall of a tyre and consists of two electrodes made of carbon nanotubes. Those electrodes are printed very close together on a flexible polyimide film.
By applying an oscillating electrical voltage to one and grounding the other, an electric field forms between the electrodes. While most of the electric field passes between the two electrodes, some of the field arcs between them. When a material is placed on top of the electrodes, it interferes with the “fringing field.” By measuring the interference through the electrical response of the grounded electrode, it is possible to determine the thickness of the tyre rubber or other material covering the sensor. The sensor currently takes the form of a decal, but the electrodes could be jet-printed directly onto the inside wall of the tyre.
In either form, the sensors will cost less than $0.01 each when mass produced. Hardware would be required for applying the voltage and for transmitting the readings to the driver. A paper describing the process and sensor design was published in the June 9 issue of IEEE Sensors Journal.