Disney Research has developed flexible paper-like generators that can generate enough electrical current to power LEDs or activate an e-paper display by being tapped or rubbed.
The generators use an electret-based energy harvesting technique (shown below) and are assembled from inexpensive materials such as paper and Teflon sheets. In tests, they were able to deliver a measured average peak power of more than 40 mW into a 1 MΩ resistive load.
As implemented at Disney Research, a paper generator made from a polytetrafluoroethylene sheet was initially charged by rubbing it with paper, forming an electret (top). The sheet was stacked with conductive layers to form electrodes (middle), which, when moved relative to each other, create a potential difference (bottom).
(Source: Disney Research)
Researchers at Arizona State University have published a paper describing how paper-folding techniques increased the areal energy density of a paper-based Li-ion battery approximately 14 times. They used fuel cells made of lithium-based powders deposited on current collectors made of paper coated with carbon nanotubes. They researchers found that folding the batteries using a Miura-ori pattern produced the greatest increase in areal energy density over planar batteries -- but with some reduction in electrochemical performance.
A recent Navigant Research report forecasts that worldwide electric vehicle charging equipment sales will reach 4.3 million units in 2020, versus 442,000 units in 2013. The report cites some growing pains, most notably the large number of players in the market and the challenge of facilitating easy consumer access to public chargers hosted by different network operators.
In product news, an isolated energy measurement chipset from Maxim Integrated allows measurement of AC or DC power use from any phase without requiring sensors, optocouplers, or an extra power supply for the measurement subsystem. Requiring only a single pulse transformer, the chipset -- the MAX78700 isolated precision ADC and the MAX78615+LMU isolated energy measurement processor -- includes nonvolatile memory and preloaded application-specific firmware that performs signal processing, compensation, and data formatting for accurate real-time measurement.
Linear Technology announced a wireless power receiver/battery charger that uses a Dynamic Harmonization Control technique that allows high-efficiency contactless charging across an air gap. The LTC4120 has an input range of 4.25-40V and features up to a 400mA of charge current that is programmed with a single resistor.
International Rectifier has introduced a 35A point-of-load (POL) integrated voltage regulator for space-constrained enterprise power applications. The IR3846 operates from 5V to 21V and has a programmable switching frequency from 300kHz to 1.5MHz.
WiTricity has introduced a simulation environment for designing and developing systems based on its Highly Resonant Wireless Power Transfer technology. Aimed at helping streamline the design process for wireless energy transfer over distance, the subscription-based WiCAD software provides modeling and simulation capabilities for resonator design, system design, and optimizing power transfer efficiency.
Finally, Efficient Power Conversion Corporation has announced the availability of a development board for high-current, high-stepdown-voltage, buck intermediate bus converter applications using the company's eGaN FETs. The EPC9017 features the 100V EPC2001 enhancement-mode FET operating up to 20A of maximum output current in a half-bridge configuration with onboard gate drives.