We've recently seen a number of battery-free implantable biosensors, that are activated by the handheld device that reads them. Scientists have now created another such sensor, that's smaller than any that have come before.

Designed to continuously monitor various bodily processes, externally-powered biosensors are not only smaller than their battery-packing counterparts, but they also don't have to be surgically retrieved for battery-changes.

They typically contain an RFID (radio frequency identification) chip, which transmits data when it's temporarily powered up by the radio signal from an external reader device – that device is in turn held near the implant site on the patient's body. In order to produce a signal that's strong enough to be read, however, the biosensor needs to be relatively large.

Led by Asst. Prof. John Ho, a team at the National University of Singapore recently got around this limitation, by creating a reader that's three times more sensitive than existing devices. As a result, the associated biosensor can be correspondingly smaller.

Asst. Prof. John Ho (left) and doctoral student Dong Zhenya, with the biosensor National University of Singapore



The current prototype sensor is just 0.9 mm in width, and has been injected under the skin of lab rats utilizing a hypodermic needle. Once implanted, it's able to monitor breathing and heart rates, based on its detection of subtle telltale movements. Once developed further, it is hoped that the technology could do much more.

"We hope that our breakthrough will be a trailblazer for the future of minimally-invasive health monitoring solutions where patients are immediately alerted whenever their physiological conditions […] cross a critical threshold," says Ho. "Now that we have proven the viability of our reader, the next step is to develop a suite of passive (battery-free) microsensors that can monitor various physiological parameters such as glucose, bioelectrical activity and blood chemistry."

The research is described in a paper that was recently published in the journal Nature Electronics.

Source: National University of Singapore