
Chip-free wireless tags are more sustainable and cut e-waste
In a paper, Engineers from the University of Glasgow have described a new wireless tag that is able to identify objects and measure temperature without relying on integrated circuits.
Inexpensive coils and a sensing material made from a form of silicon rubber called PDMS and carbon fibres mage up the wireless tag instead. Tiny coils, similar to those found in credit cards, but smaller, absorb electromagnetic signals from a hand-held reader.
The wireless tags can be read by low-cost hand-held wireless readers and are able to store ID information as well as take real-time temperature measurements.The tags are able to detect detect variations in temperature between 20°C and 110°C and react in seconds to changes in temperature.
Multiple tags can be read at once. In the paper the researchers described three sensors providing information to the reader device simultaneously. In addition, the wireless tags can function equally well at different distances from the reader.
According to the researchers the new, less wasteful tags could help reduce the retail sector’s reliance on RFID chips, which uses more than 10 billion tags each year that are typically used just once and end up in a landfill.
The wireless tags could also find applications measuring pH or humidity in next-generation packaging to provide advance warnings when food is at risk of spoiling or is outside safe environmental conditions. Other applicators could include healthcare and smart clothing to monitor vital signs unobtrusively.
Dr Mahmoud Wagih, lecturer at the University of Glasgow’s James Watt School of Engineering and the study’s corresponding author commented: “Developing wireless sensing tags is crucial for monitoring temperature across supply chains, particularly in food safety and medical applications. By eliminating the need for microchips, these chipless tags could significantly reduce both cost and electronic waste compared to traditional RFID sensors.
“While there have been various efforts in recent years to develop chipless smart devices, many require expensive specialised equipment for readout, limiting their potential in commercial applications.
“Our paper shows how multiple temperature sensors can be read simultaneously using an inexpensive portable device, which could make it an attractive prospect for adoption by a wide range of industries.”
Dr Benjamin King, also from the James Watt School of Engineering and co-author of the paper added: “The new technology we’ve developed uses materials which are cheap and widely-available, and the tags can be manufactured using a simple, scalable process. Our hope is that those unique characteristics could help the technology become widely-adopted in the years to come, helping to reduce the environmental harms currently being caused by single-use RFID tags.”
The research was supported by the UK Engineering and Physical Sciences Research Council (EPSRC), and the Royal Society.
The paper, titled ‘Large-Area Conductor-Loaded PDMS Flexible Composites for Wireless and Chipless Electromagnetic Multiplexed Temperature Sensors’, is published in Advanced Science. DOI: https://doi.org/10.1002/advs.202412066.
Image: Device prototype with thermal camera. Courtesy of the James Watt School of Engineering.
