Graphene, the electrically-conductive "wonder material" made up of a one-atom-thick sheet of linked carbon atoms, already has many uses. It now has another, however, as the active ingredient in a sensor that detects food spoilage.
Developed by scientists at Iowa State University and Northwestern University in Illinois, the prototype sensor was created by first aerosol-jet-printing graphene electrodes onto a flexible polymer substrate. Next, histamine antibodies were chemically bonded to the graphene. Although more commonly associated with allergic reactions, histamines are also given off by spoiled meat or fish.
When the resulting device is placed near a sample of either food, any histamine molecules that are present will bind with the antibodies on the graphene, blocking the transfer of electrons. This increases the electrical resistance of the material – the larger the number of molecules that are present, the greater the resistance.
Therefore, by running an electrical current between the electrodes, it's possible to measure the resistance and thus determine histamine levels. In its current form, the sensor can detect histamines down to a concentration of 3.41 parts per million. For context, the US Food and Drug Administration defines spoilage in fish as being anything over 50 parts per million.
The sensor is reportedly inexpensive to manufacture, and could easily be mass-produced. Additionally, by substituting the histamine antibodies for other types of antibodies, the system could additionally be used to detect things such as harmful bacteria or disease-associated biomarkers.
The technology is now being commercialized by Iowa State spinoff company NanoSpy. It is described in a paper that was recently published in the journal 2D Materials.
Source: Iowa State University