Netherlands-based Eindhoven University of Technology (TU/e), Universitá di Catania in Italy, France-based laboratory CEA-Liten and semiconductors manufacturer STMicroelectronics have created a circuit that tests the expiry date on food packaging.
The new plastic analogue-digital converter (ADC) has various potential uses beyond food, including for pharmaceuticals.
An electronic sensor circuit can be included in the packaging to monitor the acidity level of the food, in order to combat food waste.
In order to show the freshness of steak, or whether the frozen food was defrosted, the circuit can be read with a scanner or with a mobile phone.
TU/e researcher Eugenio Cantatore said the researchers are developing electronic devices that are made from plastic rather than silicon.
"The advantage is you can easily include these plastic sensors in plastic packaging," Cantatore said.
The plastic semiconductor can be printed on all kinds of flexible surfaces, making it cheaper to use.
Researchers have made two different plastic ADCs, each of which converts analogue signals such as the output value measured by a sensor, into digital form, and they bring applications in the food and pharmaceuticals industries within reach.
A sensor circuit comprises four components, the sensor, an amplifier, an ADC to digitise the signal and a radio transmitter that sends the signal to a base station.
"All plastic transistors behave differently in the low-cost production processes at low temperatures," Cantatore added.
The circuits printed by CEA-Liten include more than 100 n and p-type transistors as well as a resistance level on transparent plastic substrates.
Image: A newly-developed plastic analogue-digital converter has various potential uses, including for food and pharmaceuticals. Photo: Bart van Overbeeke.