A chip implanted under the skin allows for precise, real-time medical monitoring

May 27, 2015

Under-the-skin chip (credit: EPFL)

A tiny (one-centimeter-square) biosensor chip developed at EPFL is designed to be implanted under your skin to continuously monitor concentrations of pH, temperature, and metabolism-related molecules like glucose, lactate and cholesterol, as well as some drugs.

The chip would replace blood work, which may take  hours — or even days — for analysis and is a limited snapshot of conditions at the moment the blood is drawn.

Developer Sandro Carrara unveiled the chip Tuesday (May 26) at the International Symposium on Circuits and Systems (ISCAS) in Lisbon.

The electrochemical sensors work with or without enzymes, which means the device can react to a wide range of compounds, and it can do so for several days or even weeks.

Wireless power and monitoring

Implantable biosensor chip with three layers: a passive sensing platform (bottom), integrated circuits (middle) to analyze electrochemical measurements and generate a Bluetooth signal, and a coil (top) for through-the-skin data transmission and power via an external battery (credit: Camilla Baj-Rossi et al./IEEE Transactions on Biomedical Circuits and Systems)

The biochip contains three main components: a circuit with six sensors, a control unit that analyzes incoming signals, and a Bluetooth module for sending the results immediately to a mobile phone.

It also has an induction coil that wirelessly draws power from an external battery attached to the skin by a patch.

To ensure biocompatibility, an epoxy-enhanced polyurethane membrane was used to cover the device.

The chip was successfully tested in vivo on mice at the Institute for Research in Biomedicine (IRB) in Bellinzona, where researchers were able to constantly monitor glucose and paracetamol levels without a wire tracker getting in the way of the animals’ daily activities.

The results were promising, so clinical tests on humans could take place in three to five years — especially since the procedure is minimally invasive, the researchers say.

“Knowing the precise and real-time effect of drugs on the metabolism is one of the keys to the type of personalised, precision medicine that we are striving for,” said Carrara.