Scientists in Switzerland have developed a "tiny lab" on a chip that when implanted just under the skin can track levels of up to five substances in the blood and transmit the results wirelessly to a smartphone or other receiving device in a "telemedicine" network. They suggest the device could be ready for market in four years and has many potential uses, such as helping doctors monitor patients undergoing chemotherapy.

Other teams have been developing similar implantable devices, but the team from Ecole Polytechnique Federale de Lausanne (EPFL) says theirs is the first to monitor several blood markers at the same time.

Team leaders Giovanni de Micheli and Sandro Carrara say they are still experimenting with the prototype device, but it can reliably detect several commonly traced substances.

Implant and Skin Patch

The device comprises two parts: the "tiny lab" that is implanted under the skin and an "intelligent patch", that sits near the implant on the outside of the skin.

The implant measures 14 mm by 2mm, and contains five nano-sized sensors that do the detecting. It is inserted into the interstitial tissue just beneath the skin of the abdomen, or arms or legs, with a needle.

The intelligent patch is about the size of a credit card and does two things: it delivers 1/10 watt of power to the implant via induction through the skin (so no need for surgery when batteries need replacing), and it also receives data via radio waves from the implant which it processes and then transmits via Bluetooth.

The team has already tested the device for five different substances and shown it is as reliable at measuring them as traditional blood tests.

Design Challenge Involving Many Disciplines

The project to develop the device is part of the Swiss Nano-Tera initiative which aims to bring together researchers from different envrionment and medical disciplines. The team that developed this prototype includes experts in electronics, computing, biology, and medicine.

A key feature of the device's technology is the nanosensors. Great care was taken in their development, say the scientists.

The surface of each sensor is coated with an enzyme that captures the target compound, for instance lactate, glucose or ATP.

De Micheli says:

"Potentially, we could detect just about anything, but the enzymes have a limited lifespan, and we have to design them to last as long as possible."

At present, the enzymes last for about 6 weeks, which is long enough for many applications, says De Micheli. Besides, because the implant is so small, it is not difficult to remove and replace it with a new one.

Another challenge for the design was the electronics, especially the tiny electrical coil that receives inductive power from the patch.

"It was not easy to get a system like this to work on just a tenth of a watt," says De Micheli.

He and his colleagues hope the device will be commercially available within 4 years.

Potential Applications Include Personalized Chemotherapy

The scientists believe the device will help doctors provide more personalized care to their patients than traditional blood tests can provide.

They will be able to monitor patients continuously, a great advantage when treating those with chronic illness or undergoing chemotherapy, for example.

At present, oncologists monitor cancer patients' progress and tolerance to dosage during chemotherapy with regular blood tests.

De Micheli expects the device will help them administer the optimal dose much more easily.

"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 explains.

Another potential use for the implant is where monitoring substances in the body can anticipate the need for intervention or medication, sending out alerts when levels reach a critical point.

In a video interview Carrara gives the example of how some hours before a cardiac event like a heart attack, metabolites are released into the bloodstream. The device could be primed to detect these metabolites and send out an alert.

Another potential application is helping diabetics keep their blood sugar under control.

Research results are being presented on 20 March at the Design, Automation, and Test in Europe conference (DATE 13).

Another example of moving toward personalized chemotherapy has recently been unveiled by UK scientists who suggest a blood test that tracks fragments of DNA shed by dying tumor cells could one day be used to monitor how well patients are responding to cancer treatment.





Written by Catharine Paddock PhD