Fujitsu used CEATEC 2011 to show off one of the more intriguing future technologies that we have seen.
Called a Hybrid Power Generation Device and using 'energy harvest technology', the idea is that you wear a chip on your skin that gets energy from both the sun and your own body heat – in turn it will use these readings to monitor the body's health and send data back to a monitoring system.
This is the first self sufficient chip of its kind that can harvest energy both from light and heat.
Usually separate chips are needed, a photovoltaic cell and some sort of thermoelectric element, but the clever bods at Fujitsu have managed to produce a hybrid device.
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The chip was not in operation when we used it, but a spokesperson for the company told us that it is able to generate 700 microwatt of power from the energy it harvests and this means it needs no battery to work.
The chip isn't big, it measures 5cm x 5cm and has been designed to stick to the wrist of whoever uses it.
Fujitsu was one of many companies that tapped into the health market for this year's CEATEC, which also included smartphone cases that act as health monitors from DoCoMo.
We did ask if this sort of technology could be used in the future to power things like smartphones – 'My phone's battery is dead, let's jack it into my body!' – but it seems that for now the focus is purely on giving you a health check-up and not powerful enough to power products.