Researchers at Tufts University have developed a wireless, passive radio frequency identiﬁcation device (RFID) built entirely from silk. This ﬂexible sensor consists of a gold RFID antenna array on a silk polymer substrate. The array is less than 100 micrometer thick, and is fully biocompatible.
Passive RFID tags applied to flat surfaces are widely used for inventory management and anti-theft protection. However these are not easily extendable to curved surfaces, not capable of sensing the local environment and not biocompatible requiring their removal before biomedical use or before ingestion.
Silk‐based RFID technology provides a cost‐eﬀective and “green” alternative to traditional RFID manufacturing. These passive sensors are capable of continuous monitoring for a variety of commercial applications. Silk biomaterials, including this RFID tag, are highly robust and non-immunogenic. This sensor can therefore be safely implanted or ingested. While silk biopolymers exhibit remarkable strength, they can also be reprogrammed to degrade over the course of hours to weeks depending on the desired application.
A variety of silk‐based metamaterials have now been developed. This passive RFID sensor has already been used by the researchers to continuously monitor food spoilage on fruit and dairy products. The sensor is easily fabricated to work across multiple regions (MHz, GHz, THz) of the electromagnetic spectrum, and it can be applied to a variety of substrates, including the curved surfaces of fruit skin.