With the Sensor Systems & Applications Global Technology Field (EEE Cluster), Fleischer develops sensors embedded in microchips, which detect the presence of chemicals indicative of odors or gases. For example, the gallium oxide sensor, which was the breakthrough invention in Fleischer’s career, has for several years been used to measure the CO content of exhaust gas in thousands of small combustion units, enabling these units to be operated in an energyefficient way with minimum emissions. The units are complemented by sensors that monitor the air quality in buildings. Other sensors use laser light to detect poisonous or explosive gases in buildings. This is particularly important in the case of gas or bomb alarms, since this method works at distances of up to 20 meters.

The sensors, which measure only a few square millimeters, are based on very diverse processes. For example, some sensors consist of semiconducting metal oxides that are applied as a thin film to the surface of a chip. Any gas that docks with the device changes its electrical resistance, and the resulting signal is read by a processor on the chip. Fleischer’s team has now succeeded in placing different gas-sensitive receptors on one chip in order to be able to detect more than one gas at a time. The researchers are already using living cell cultures located on silicon chips to perform tasks such as monitoring water quality. The advantage here is that living cells react to all toxins, whereas with chemical sensors one has to determine in advance which hazardous substance is to be detected.

A sensor’s main purpose is generally to save energy and conserve resources. For instance, a prototype “wellness sensor” that was developed by Fleischer’s team determines when the CO2 content of the air in offices or meeting rooms is too high and recommends that the ventilation be regulated before the occupants become too tired and unfocused to go on. Because around half of a building’s energy use is related to ventilation, a needs-focused system can achieve big savings.

Fleischer’s inventions have benefited Siemens for a long time, because other companies that use his technology have to pay licensing fees to Siemens. Fleischer, a physicist, has been working at the Corporate Technology research center in Munich since 1992. During that time, he has registered over 160 inventions. He was already named “Inventor of the Year” back in 2003 – and he continues to come up with new ideas, which he also communicates to his students at the University of Budapest, where he is an honorary professor and teaches about applications derived from research results.

“I don’t sit alone in my room, I go out into the world with a sense of curiosity,” he says. For example, he once heard about a traditional practice of Chinese doctors, who check their patients’ breath because its odor can be a sign of illnesses. This inspired him to invent sensors that could detect substances in human breath. Thanks to this work, sensors can now be used to help asthma patients determine whether an asthma attack is imminent. Fleischer has found his ideal sphere of action at Siemens. As he puts it, “Siemens operates in many different areas, so my inventions can be implemented in many new applications. Cooperation at the company is great; my colleagues are not solitary workers but team players. That’s crucial, because to develop fundamentally new things, you need good colleagues.”