Solar Cells Applied Directly to Silicon Chip Can Power Wireless Sensors

Small solar cells attached directly to a silicon chip can potentially serve as an efficient and reliable power source for wireless sensor networks (WSN). This new technology developed by researchers from the Fraunhofer Institute for Microelectronic Circuits and Systems would greatly simplify large-scale WSN applications, for instance in agriculture.

The solar cell sits directly on the sensor module’s silicon chip. (Credit: Fraunhofer IMS)Almost wherever you go, a team player is more in demand than a lone wolf—after all, those who pull together get the better results. This isn’t just true for people though: sensors, too, are more powerful when part of a team. Sensor networks made up of individual sensor modules that communicate wirelessly with one another have the capacity to measure local parameters over large areas, and then to pass these data on among sensor modules to a central station. This makes sensor networks suitable for a wide range of applications, whether for fire prevention or monitoring large areas of farmland. The issue of how to power the individual sensor modules remains a sticking point in these sorts of applications.

Wiring the sensors together is hardly a viable option nowadays due to the cumbersome and costly installation. What’s more, many applications require the sensor network to blend unobtrusively into the surroundings and not to have an impact on the aesthetics. An example of this would be the systems used for adjusting window positions as part of smart building management programs. Using batteries to power the sensor network does eliminate the need for inconvenient cables, but the amount of maintenance involved in replacing the batteries regularly as required should not be underestimated, particularly in large networks.

Now, researchers from the Fraunhofer Institute for Microelectronic Circuits and Systems IMS have developed an ingenious alternative based on SOLCHIP Ltd IP. The resource they have harnessed to provide power is one that is freely available in almost any location: sunlight. “We use special process steps to place a mini solar cell straight on sensor modules’ silicon chips,” explains Dr. Andreas Goehlich, who heads up the project for Fraunhofer IMS.

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