During high-risk medical operations surgeons keep blood supplies at hand so that they are ready to face possible emergencies; but blood bags can only be reused if the cold chain has been maintained, meaning that a portion of such a precious and limited resource routinely goes wasted. To face this problem, researchers at the Fraunhofer Institute in Germany have proposed intelligent blood bags with an embedded a radio chip that constantly monitors temperature and checks for blood type compatibility with the patient, avoiding possible mistakes.

The idea is conceptually simple, although very promising. The main issue that the researchers had to face when putting the idea into practice was to enable radio communication without interfering with medical equipment, which they achieved by using lower-power communication via intelligent radio nodes.

"In contrast to tags that use radio frequency identification, we do not expect intelligent radio nodes to interfere with hospital medical devices," head of the communication networks department at the Fraunhofer Institute for Integrated Circuits Jürgen Hupp explained. "While the transmit power required for RFID tag reading can be as much as two watts, radio nodes only transmit in the milliwatt range."

Another important advantage of communicating with these intelligent radio nodes rather than with RFID tags is that the latter must first be manually activated by the reader, while the former can continuously gather information and independently trigger actions, drawing the necessary power from a battery and relying on a small processing unit to interpret incoming data.

The system is built on a flexible platform, meaning that the radio nodes could be used not just to monitor temperature in a blood bag but also — with the aid of additional information coming from a radio-enabled wristband worn by the patient — to prevent dangerous mistakes by determining whether the blood to be transferred is compatible with the patient's type, sending a warning signal in case of incompatibility.

But the flexibility of the system goes even further. Another application devised by the team is to monitor the location of various medical instruments that are often moved around and are sometimes hard to track. Knowing the exact location of syringe pumps and cardiac monitors at any given time by embedding an intelligent radio node can once again allow for a swifter retrieval and reduce the number of necessary equipment, cutting costs for hospitals and patients.

The project is funded by the German federal ministry of economics and technology and will undergo a six-month test phase set to begin at Erlangen University Hospital in January 2010.