Self-powered wireless light detectors

Mar 12, 2014
Self-powered wireless light detectors
Ferroelectric compounds used in photodetectors can help to minimize electrical losses, facilitating a sensor and monitoring network that can go ‘off the grid’. Credit: Glida46/iStock/Thinkstock

Light detectors are used extensively in daily life as brightness sensors and as receivers for remote control devices in electrical gadgets, for example. However, operating these detectors requires electrical energy, which limits their versatility.

Now, Kui Yao and colleagues from the A*STAR Institute of Materials Research and Engineering in Singapore have developed a that can harvest just small quantities of detected light to generate enough energy to power a sensing signal transmission through a radio-frequency transmitter.

While the energy contained in a beam of light can be converted into electricity, this energy is not usually sufficient to continuously power an electrical circuit. Even the use of batteries to power a circuit is impractical in many circumstances, explains Yao. "Use of photosensors may take place under extremely harsh conditions intolerable to batteries, or involve environmental monitoring network systems where it may be too expensive or unrealistic to maintain batteries for each sensor."

Operating an electrical circuit under low-power circumstances requires a buildup of energy, which must be generated by the photodetector. However, commonly used photodetector materials, which are based on semiconductors, lose too much energy for this to occur. "Conventional photodetectors can't accumulate the minute photovoltaic energy and then harness it to drive a load in a sustainable manner," explains Yao.

To overcome such losses, Yao and colleagues developed photodetectors made from ferroelectric compounds. These insulating materials can separate electrical charges as well as store them with low losses. Ferroelectric detectors can also generate a larger electrical voltage than semiconductors, making it easier for them to power other electrical components.

The researchers connected their ferroelectric detector to a specially designed electrical circuit, which is mechanically opened and closed by a switch in the form of a piezoelectric cantilever. Any generated electricity is temporarily stored in the ferroelectric detector and a capacitor. Once the of the capacitor is sufficiently high, the cantilever changes its shape and closes the . This activates a commercial radio transmitter.

So far, the team's main challenge in developing the device has been to minimize electrical losses. Remarkably, Yao and his team have shown that almost 70 per cent of the accumulated electrical charge can be retrieved from the capacitor—even ten minutes after the light source has been switched off. This advantage provides the team's device with the potential for use in a wide range of applications, such as wireless optical sensors and monitoring networks.

Explore further: Kinetic battery chargers get a boost

More information: Lai, S. C., Yao, K. & Chen, Y. F. "A battery-less photo-detector enabled with simultaneous ferroelectric sensing and energy harnessing mechanism." Applied Physics Letters 103, 092903 (2013). dx.doi.org/10.1063/1.4819845

add to favorites email to friend print save as pdf

Related Stories

Kinetic battery chargers get a boost

Feb 19, 2014

New technology to capture the kinetic energy of our everyday movements, such as walking, and to convert it into electrical energy has come a step closer thanks to research to be published in the International Journal Biomechatronics an ...

Graphene photodetector integrated into computer chip

Sep 16, 2013

The novel material graphene and its technological applications are studied at the Vienna University of Technology. Now scientists succeeded in combining graphene light detectors with semiconductor chips.

Recommended for you

Controlling core switching in Pac-man disks

Dec 24, 2014

Magnetic vortices in thin films can encode information in the perpendicular magnetization pointing up or down relative to the vortex core. These binary states could be useful for non-volatile data storage ...

Atoms queue up for quantum computer networks

Dec 24, 2014

In order to develop future quantum computer networks, it is necessary to hold a known number of atoms and read them without them disappearing. To do this, researchers from the Niels Bohr Institute have developed ...

New video supports radiation dosimetry audits

Dec 23, 2014

The National Physical Laboratory (NPL), working with the National Radiotherapy Trials Quality Assurance Group, has produced a video guide to support physicists participating in radiation dosimetry audits.

Acoustic tweezers manipulate cell-to-cell contact

Dec 22, 2014

Sound waves can precisely position groups of cells for study without the danger of changing or damaging the cells, according to a team of Penn State researchers who are using surface acoustic waves to manipulate ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.