December 10, 2010 – Fujitsu Labs says it has developed a hybrid device that harvests energy and generates electricity from either heat or light, resulting in an economical device with potential use in sensor networks and medical technologies.

The technology, unveiled at this week’s IEEE International Electron Devices Meeting (IEDM 2010), addresses a key application sweetspot for such technology. Energy harvesting — converting energy from the surrounding environment to electricity, using anything from light, vibration, heat, even radio waves — removes the need for electrical wiring, power cords, and batteries, which could not only enable use of sensors in new applications and regions but also improve their use (and lower their costs) in existing ones.

The problem, though, is that energy harvesting can only put out a fraction of the power that batteries can, so more powerful devices need to be made. And since some types of devices may not work in some ambient environments (e.g. light or vibration), energy harvesting systems put together several types of these devices utilize multiple forms of external energy (e.g. heat and light, or light and vibrations). An ideal device, then, would combine the ability to convert multiple energy types.

Enter Fujitsu Labs, which says its single device can capture energy from either light or heat (the most typical forms of ambient energy), by connecting two types of semiconductor materials (P-type and N-type semiconductors) that can function as a photovoltaic cell or thermoelectric generator (Figure 1). It also can be manufactured from inexpensive organic materials to keep production costs low.

Figure 1: Single device featuring operation in both photovoltaic mode (left) and thermoelectric mode (right). (Source: Fujitsu Labs)

The technology doubles the energy-capture potential by using both ambient heat and light. In medical fields, for instance, sensors could monitor conditions such as body temperature, blood pressure, and heartbeats without batteries or electrical wiring; if neither energy source is sufficient to power the sensor, it can tap and utilize both sources. Another application: environmental sensing in remote areas for weather forecasting, where battery replacement or electric lines are problematic.

Fujitsu says it will continue to improve the hybrid device’s performance toward planned commercialization around 2015.

Figure 2: Prototype hybrid generating device manufactured on flexible substrate. (Source: Fujitsu Labs)