acquisitionZONE Products for the week of February 5, 2007
Advanced Linear Devices Inc., a design innovation leader in analog semiconductors, announced the industry's first energy harvesting modules designed specifically to capture, accumulate and store power from a variety of energy harvesting sources and supply it to wireless sensor networks, remote controls and a multitude of other applications. The module's outstanding energy efficiency is designed to make energy harvesting a reliable and long-lasting source of power and can help unshackle many applications from the constraints of battery or AC power sources.
ALD's EH300 and EH301 EPAD Energy Harvesting Modules can accept energy from an assortment of widely available waste energy sources the operate from vibration, light, chemical reaction, fluid and air flow, environmental heat and others. The modules then store this energy to power conventional 1.8V and 5.0V electrical circuits and systems such as wireless sensor networks designed to the ZigBee standard.
ALD EPAD Energy Harvesting Modules are completely self-powered and always in the active mode, always ready to harvest energy from sources that generate intermittent energy impulses with varying source impedances. The modules begin operating from 0.0V and operate at zero power to ensure that even the most miniscule energy charges can be captured, stored and used for the application. The zero-power operation of the circuit ensures that very little of the energy is squandered on the module's own operation. The modules are also designed to store and manage the energy for extended periods of time with minimal leakage or loss to supply power to the application when it is most needed.
"Energy Harvesting modules provide a crucial link between the source of the energy, such as piezoelectric or thermoelectric materials, and the application. The energy provided directly by these sources is often produced in uncontrollable spikes with a wide range of voltages, currents, and waveforms," said Bob Chao, President and CEO of ALD. "Using components built with ALD's patented EPAD technology, we've developed electronic modules capable of capturing these energy sources with maximum efficiency to make these applications useful and practical. Up until now, it has been very difficult for developers in this field to capture the energy generated by these sources. By commercializing these important modules, ALD is providing the catalyst to this emerging application area to help it overcome some of the limitations that have held back the promises of energy harvesting."
Circuits built with conventional, off-the-shelf components are often incapable of providing the efficiency needed to make energy-harvesting a practical solution. Building circuits with conventional components usually required significantly more electrical energy to operate both the circuit and the application. The power generated by piezoelectric or thermoelectric materials, for example, often occurs at infrequent or random intervals and is usually not sufficient to directly and dependably power both the circuitry and the application.
"Piezoelectric fiber composites have a bright future in energy harvesting
for ultra low power embedded electronics," said Steve Leschin, managing
director of business development for Advanced Cerametrics Inc. "Our
company has focused on developing energy harvesting materials to provide
extreme life span power in the area of remote, wireless sensor networks.
We discovered that this requires a multi-disciplined approach that leverages
knowledge in several different fields. ALD's electronic energy harvesting
modules solve a key part of the equation by accumulating, storing, and managing
power from piezoelectric fiber composites. These modules serve as an essential
power management stage for embedded applications."
analogZONE Says . . .
Energy harvesting has been a dream for many decades. In the last decade work has sped up, driven mostly from money from DARPA (the US Defense Advanced Research Projects Agency), which would love to see the heavy rechargeable batteries that a soldier needs to carry replaced by a harvested source. And, indeed, items like the heel strike generator have been proven in the field to produce 3 W to 7 W, in practical terms.
Not that many years ago Seiko offered a watch (the THERMIC) powered by the wearer's body heat (using the Peltier-Seebeck Effect) and it is not unimaginable to see a future where all the heat produced in an office space, say, could not be harnessed as energy for another application. Architects are already working on buildings that recycle such energy, one such being Facility Architects which envisions people powering displays in railway stations; charging their iPods from their walking; traffic powering the traffic lights they are approaching. Sir Trevor Baylis, well known as the designer of the wind-up radio, was working a few years ago on a shoe battery, which would charge as the user walked -- his plans were kind of scotched after Richard Reid attempted to down an airliner with his allegedly explosive shoes, making electronics in footwear (apart from childrens' sneakers, it seems) a large no-no in the world's airports.
The sources for energy harvesting are limitless but the main candidates that researchers see today can be defined simply as light, vibration and thermal. One of the most important sources is likely to be from piezoelectricity. As we well know in electronics, piezoelectric crystals can behave strangely, and one of the most useful effects is to provide a spark of energy when you subject it to mechanical shock: turning on your gas oven, for instance. The voltage produced can be extremely large (100 kV from a 50 µm distortion of lead zirconate titanate, for example) but the currents are tiny. We also know, of course, that we can vibrate such crystals to produce accurate frequencies -- a characteristic first used in sonar in WWI: a really early example of electronics.
Capturing such energy is a challenge because the devices that have done so up until now use more energy than the total captured. Enter ALD's EPAD (electronically-progammable analog device) technology. This technology earned the company an analogZONE Product of the Year Award in 2005 for their near-zero threshold MOSFETs. This allows for very low leakage currents, making the capture of energy to be much more efficient, thus leaving more of it to be stored in a capacitor.
The modules consist of a detector, storage and a switch to connect the device to its load. ALD sees the main use of the system to be as a power source for a function that is in a remote location, perhaps with no line power access or in a difficult location for changing batteries. One can imagine, for example, earthquake fault-line monitoring with the sensor buried with no access to even solar power. As the energy source slowly charges the part, the load is not connected. As soon as sufficient charge is held, the output switch connects it to the load and powers it up for sufficient time to transmit its sensor values, or wake up a microprocessor, or fire a weapon… All the control is from EPAD comparators.
The initial series of EH300 modules can operate on ac or dc sources from 0 V to ±500 V and with input currents from 200 nA to 400 mA (maximum input power is 500 mW). The EH300 allows for 1. 8 V to 3.6 V operation with an output of 4.6 mJ (about 70 mW for 68 ns, say 25 mA at 2.8 V). The EH300A increases the output energy to 30 mJ while higher voltage versions, with 3.1 V to 5.2 V operation, provide 8.3 mJ in the EH301 and 55 mJ in the EH301A. There is an on-module 7 V (at 10 mA) clamp.
These early versions provide more than enough power for the intended ZigBee applications that the company foresees. As a battery/ac power replacement, the modules should offer a virtually unlimited life cycle, with an infinite number of charges/discharges. The applications are going to go well beyond ZigBee. I have no doubt that the military are/will be sniffing around the ALD offices in - very familiar for them - Tasman Drive. There is no indication in the ALD materials that they are, or have been, seeking out a partner to provide an incoming energy source, but a huge number of companies will find them. Traction in something this novel is extremely difficult to forecast and the company itself has never been inspired to toot its own horn very loudly. Something like this needs to be sold, and sold hard, if the innovation lead is going to be commercially successful. For those reasons...and always being aware that this is the kind of technology that could be instantaneously shut off to OEMs by an Executive Order from the White House...I am not going to predict the success of the products. In the right hands this could be huge, absolutely dramatically huge. The first mistake in this launch could well be the pricing.
The EH300/301 modules are in production in a Pb-free circuit board (unsealed) of 0.5 inch width, 2.0 inch length and 0.7 inch height. It weighs a nominal 14 g. Pricing is $36.54 in 1000-piece lots.