The sensor
consists of four areas with different metal oxides. They change their
temperature-dependent
electric resistance when coming into contact with gases.
(Photo: KIT/HsKA)
(November 26, 2015) Hybrid
Sensors Detect the Risk of Fires before They Can Even Be Noticed by Smell or
Discoloration of Cable Insulations
Fires are frequently caused by smoldering cables. Novel
sensors now help detect such smoldering fires at an early stage by analyzing
the plastic vapors released by overheated insulating cables. Scientists of KIT
and Karlsruhe University of Applied Sciences have developed these hybrid
sensors that combine measurement processes with data evaluation. Their work is
reported in the current issue of the Sensors & Transducers Journal.
A smoldering cable can be detected with a little luck before
it starts burning: The plastic coating changes color, there is a smell of
burning. Hybrid sensors might detect the risk of cable fires earlier, even
before they are perceived by eyes and nose. They detect the gases released from
the plastic coating due to heating and reliably identify and analyze the gas
mixture and its concentration.
In addition, they can also detect interfering gases, such as
propene or carbon monoxide, and, hence, exclude false alarms. To this end, the
hybrid sensors do not only possess a gas-detecting sensor chip, but also the
computation capacity and algorithms needed for evaluating measured data. “The
combination of a smart evaluation process with physical measurement is the
basic idea of this development,” Dr. Hubert Keller, Simulation and Measurement
Project Head of KIT’s Institute for Applied Computer Science, explains.