Researchers at Georgia Institute of Technology have discovered a way to produce electricity from random mechanical motion using triboelectric nanogenerators. These are devices fabricated from flexible polymeric materials with a high degree of transparency. Rubbing the surface of these devices can generate alternating current from friction.

The research was published in the June issue of Nano Letters.  The proponents of the study were Zhong Lin Wang, Feng-Ru Fan, Long Lin, Guang Zhu, Wenzhuo Wu and Rui Zhang. Fan is also connected with Xiamen University of China.Triboelectric nanogenerator operates when a sheet of polyester rubs against a sheet made from polydimethylsiloxane (PDMS). The polyester donates electrons while the PDMS accepts electrons. When the two surfaces are mechanically separated, a voltage drop develops between them. Connecting an electrical circuit between them causes a current flow to equalize the charge differential.

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Over the years, we’ve seen researchers develop some rather unorthodox energy harvesting systems, including photovoltaics (solar panels), piezoelectric materials that react to motion, and thermoelectrics that turn heat into electricity.

Now, MIT Professor of Electrical Engineering Anantha Chandrakasan and MIT doctoral student Saurav Bandyopadhyay are working on a chip that can harvest energy from all three of the same sources at the same time.According to the researchers, the chip can generate up to 0.15 volts from thermal differences, 0.7 volts from natural light, and five volts from vibrations. While each power source only produces a small amount of electricity, the researchers have found a way to effectively combine the energy from all three methods by rapidly switching between them.

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Radio sensors can monitor installations at locations which are difficult to get to and thus support automation. In these circumstances the energy supply is an important consideration; In order to remove the need for batteries and the associated servicing work, it is now possible to use energy from the surrounding environment by harvesting energy.

Piezoelements convert the kinetic energy from vibrations or shocks in the surrounding environment into electrical energy, and when equipped with the appropriate electronics they can create an autonomous system. PI’s robust DuraAct piezo actuators are laminated in plastic and are perfect for energy harvesting. They are reliable, durable and simple to handle and can even utilise displacements up to the millimeter.

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The Piezoelectric Playground, a temporary structure designed by Margot Krasojevic for a park in Belgrade, Serbia, was conceived of as both a playground and a bandstand.

Whenever agitated by movement and vibration (such as that produced by children playing, or even by passing traffic), the structure’s glass-clad canopy lights up in holographic, flashing patterns, illuminating whatever is happening beneath. (Just try to get the kids off of this one.)

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A very interesting piece on EE times has been written describing some of the emerging applications for vibrational energy harvesting technologies based on tens to hundreds of microwatts power generation. Take a look at EETimes for the story and more links to a recent commercial win for MicroGen who wins $200K Emerging Business Competition for energy harvesting technology.

Prof. Markys Cain has been interviewed by BBC Click in relation to NPL’s work on Energy Harvesting.

Watch the full interview on BBC iPlayer

Professor Keon- Jae Lee’s research team, KAIST (Korea), has developed a nanocomposite-based nanogenerator that successfully overcomes the critical restrictions existed in previous nanogenerators and builds a simple, low-cost, and large-scale self-powered energy system.

The team produced a piezoelectric nanocomposite by mixing piezoelectric nanoparticles with carbon-based nanomaterials in a polydimethylsiloxane matrix and fabricated the nanocomposite generator by the simple process of spin-casting or bar-coating method.

The team of Professor Keon Jae Lee from the Department of Materials Science and Engineering, KAIST, has developed new forms of low cost, large-area nanogenerator technology using the piezoelectric ceramic nanoparticles.

Piezoelectric effects-based nanogenerator technology that converts existing sources of nonpolluting energies, such as vibrational and mechanical energy from the nature of wind and waves, into infinite electrical energy is drawing immense interest in the next-generation energy harvesting technology. However, previous nanogenerator technologies have limitations such as complicated process, high-cost, and size-related restrictions.

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To the long list of exceptional physical properties of graphene, Stanford University engineers have added yet another: Piezoelectricity, the property of some materials to produce an electric charge when bent, squeezed, or twisted. The results were described recently in a paper published in ACS Nano.

Graphene is a wonder material. It is a hundred times better at conducting electricity than silicon. It is stronger than diamond. And, at just one atom thick, it is so thin as to be essentially a 2D material. Such promising physics have made graphene the most studied substance of the last decade, particularly in nanotechnology.

Yet, while graphene is many things, it is not piezoelectric.

Perhaps most valuably, piezoelectricity is reversible. When an electric field is applied, piezoelectric materials change shape, yielding a remarkable level of engineering control.
Piezoelectrics have found application in countless devices from watches, radios and ultrasound to the push-button starters on propane grills, but these uses all require relatively large, 3D quantities of piezoelectric materials.

The Stanford team’s engineered graphene has, for the first time, extended such fine physical control to the nanoscale.

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