New help may be on the way for healthcare personnel tasked with monitoring multiple patients. Researchers from the University of Tokyo have created a solar-powered arm band, that sounds an alarm if the wearer's body temperature gets too high.

The device consists of a flexible amorphous silicon solar panel, a piezoelectric speaker, a temperature sensor, and a power supply circuit. All of these are created using organic components, which are ink jet-printed onto a polymer film. It can be worn either over clothing or directly against the skin.

When the temperature sensor detects that the patient's body temperature has risen above a given range, the speaker provides an audible alarm. This is apparently the first time that an organic circuit has been used to create sound, and also the first instance of one featuring an organic power supply circuit. That circuit boosts the solar panel's range of operational indoor illumination by 7.3 times.

The arm band requires no external power supply, it's flexible enough that it doesn't cause discomfort to the patient, and it's cheap enough to dispose of after each use, in order to maintain hygiene.

"Our fever alarm armband demonstrates that it is possible to produce flexible, disposable devices that can greatly enhance the amount of information available to carers in healthcare settings," said Prof. Takao Someya, who co-led the research along with Prof. Takayasu Sakurai. "We have demonstrated the technology with a temperature sensor and fever alarm, but the system could also be adapted to provide audible feedback on body temperature, or combined with other sensors to register wetness, pressure or heart rate."

A paper on the research is being presented at the 2015 IEEE International Solid State Circuits Conference, in San Francisco.