RFID sensors to track produce

Engineers at the Syngenta Sensors University Innovation Centre plan to integrate sensors with radio-frequency identification (RFID) technology to track the stresses suffered by perishable goods along the supply chain.

Dr Bruce Grieve, director of the Syngenta Sensors University Innovation Centre at Manchester University, told The Engineer Online that the new sensors will actually measure the state of the food in the packaging by tracking the temperature that it is exposed to over time.

'We will initially be using time tracking alone as this is the key characteristic that needs to be locally monitored within the chilled supply chain for perishables,' he said. 'However, the technology is road-mapped to then accommodate additional features, notably humidity [as that is an important means to measure fungal growth and respiration]. After that, ethylene would be the next most prominent feature to track, especially due to its ripening effect in fruit.'

Grieve added that integrating an RFID system onto the same silicon as the sensor should be straightforward, as an RFID system is a reasonably simple circuit that can be sourced through an existing mainstream supplier.

'Our time-recording technology is ring-fenced as an entirely separate entity from the passive RFID circuit,' he said. 'The latter will be interfaced to the sensor element by replacing part of the "hard-wired" identity code in the passive RFID with the digital data that will be collected by the sensor system as it tracks the produce along the supply chain.'

A standard RFID reader would be the only additional peripheral needed to complete the entire system, although Grieve admitted that it may need some software/firmware adaption to accommodate what will be a longer ID code that would contain both the RFID tag's identifier number and the recorded data.

The economic motivation behind the work is to reduce the hidden costs that the public bears when purchasing fresh produce. Only a percentage of that produce makes it all the way to our plates, meaning that when we shop we are paying an invisible fee for these losses.

Grieve also highlighted the environmental benefits of the technology, which should reduce the amount of unfit produce that reaches the shelves. 'This will also help reduce fuel usage by minimising the transportation of stressed and rejected produce,' he said. 'It could also help reduce the environmental impact of unfit produce going into landfill.'

The first generation of the sensors will be based on silicon but the researcher's plan is to the use plastic printed electronics in later generations to make the sensor tags comparable in cost with the humble barcode.

'This is adventurous research and the sensor won't be with us tomorrow,' added Grieve. 'Realistically, we will have ironed out the major scientific hurdles by around the end of 2010 and then there is a significant step to translate this into a final device using appropriate manufacturing techniques.'

The commercial silicon sensor tag could be on the market in about three years, whereas the printed plastic equivalent may be here in 2015. It is hoped that the sensor would cost around £0.10 to £0.20 - a price point that would help fuel its widescale deployment.

Dave Wilson