Probe implant sends health report through Bluetooth

The team at ?cole Polytechnique Fédérale de Lausanne has integrated five sensors, a radio transmitter and a power delivery system into a few cubic millimetres so the device can be implanted under the skin of the patient. Outside the body, a battery patch provides 1/10 watt of power, through the patient's skin so that there's no need to operate every time the battery needs changing. The project is part of the Swiss Nano-Tera programme, whose goal is to encourage interdisciplinary research in the environmental and medical fields.

The probe can detect up to five proteins and organic acids simultaneously, and then transmit the results directly to a doctor's computer via a Bluetooth link to a mobile phone. This method will allow a much more personalized level of care than traditional blood tests can provide. Health care providers will be better able to monitor patients, particularly those with chronic illness or those undergoing chemotherapy. The prototype, still in the experimental stages, has demonstrated that it can reliably detect several commonly traced substances.

To capture the targeted substance in the body – such as lactate, glucose, or ATP – each sensor's surface is covered with an enzyme. "Potentially, we could detect just about anything," said Professor Giovanni de Micheli. "But the enzymes have a limited lifespan, and we have to design them to last as long as possible. The enzymes currently being tested are good for about a month and a half; that's already long enough for many applications. In addition, it's very easy to remove and replace the implant, since it's so small."

The design was a considerable challenge. "It was not easy to get a system like this to work on just a tenth of a watt," said de Micheli. The researchers also struggled to design the minuscule electrical coil that receives the power from the patch.

The implant could be particularly useful in chemotherapy applications. Currently, oncologists use occasional blood tests to evaluate their patients' tolerance to a particular treatment dosage. In these conditions, it is very difficult to administer the optimal dose. De Micheli is convinced his system will be an important step towards better, more personalized medicine. "It will allow direct and continuous monitoring based on a patient's individual tolerance, and not on age and weight charts or weekly blood tests," he said, and hope sit can be available commercially in the next four years.

- Nick Flaherty
??EE Times Europe