Weizmann Institute
Water is essential for life, but when it is in the wrong places it can cause a lot of trouble. When water mixes with fuel, lubricants or organic solvents, it can disrupt the operation of engines, cause metal parts to rust, prevent desired chemical reactions and cause unwanted reactions. That is why special laboratory tests are carried out in the industry to detect tiny amounts of water that may have penetrated into unwanted places. The known and existing test is based on a complicated process that lasts a relatively long time. A faster and simpler process was recently developed in the laboratory of Dr. Milko van der Boom from the Department of Organic Chemistry at the Weizmann Institute of Science.
Together with the postdoctoral researcher, Dr. Tarakshwar Gupta, Dr. van der Boom created a thin and versatile molecular layer with a thickness of 1.7 nanometers (a nanometer is one billionth of a meter). This layer, which is attached to the glass, is able to detect individual molecules of water even when they are inside another substance, at a ratio of one to a million.
"Water has no color and no smell," says Dr. van der Boom, "therefore it is difficult to distinguish and quantify it." Most of the detection systems that exist today are based on relatively weak - but selective - interactions between "guest" material and "host" material. In contrast, the new detection system developed by Weizmann Institute scientists is based on metal groups that are embedded within the molecular layer of the detector. These groups "steal" electrons from the water molecules. When the number of electrons in the metal groups changes, their color changes accordingly, a phenomenon that can be noticed using systems that translate the intensity of the detector's color changes into the amount of water detected.
Such a test may last only five minutes. The thin molecular layer of the detector maintains its stability even at high temperatures. Dr. van der Boom says that detecting substances through electron transfer may, in the future, be used to identify and monitor tiny amounts of other substances, such as metals and various pollutants.
