Archive for March, 2009

Wireless power energizes wireless sensors networks

March 30th, 2009


An article by Harry Ostaffe of Powercast was recently published in Industrial Embedded Systems.

The article is titled “Wireless power energizes wireless sensor networks”, and discusses how wireless power enabled by RF energy harvesting can provide a controllable and perpetual source of energy for wireless sensors.  The opening paragraphs are included below.

Battery replacement in wireless sensors is a key factor in limiting device location and scale. Through RF energy harvesting, wireless power can recharge wireless sensors remotely and eliminate battery replacement.

Wireless sensor applications and installations continue to grow as the technology evolves. The ability to add remote sensing points without the cost of running wires is resulting in numerous benefits, including energy and material savings, process improvements, and productivity increases.

Disposable, primary batteries typically supply the main power source for wireless sensors. Primary batteries are a readily available power source and have proven to be useful in many applications. However, with primary batteries as the source of power, sensor and component companies have had to focus on decreasing power consumption to overcome the objections of maintenance cost and disruption from repeated battery changes. The resulting benefit is that wireless sensors and protocols are now sufficiently low power as to be powered from sources of energy other than primary batteries.

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Ambient RF energy harvesting from iPhone

March 25th, 2009

The short video embedded below shows LEDs being powered from the RF energy harvested from an iPhone operating in 2G mode.  When the phone is called it is emitting enough RF energy to power the LEDs driven by Powercast’s RF energy harvesting technology and a simple dipole antenna tuned for the 900MHz ISM band.  We added the Powercast logo to the iPhone, but there is no Powercast technology inside.  The sound is a litte low so you might have to turn up the volume a little bit.

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Powering the TI eZ430-RF2500 wireless sensor with radio waves

March 18th, 2009


An interesting project we’ve been working on is to power the Texas Instruments eZ430-RF2500 wireless sensor demo system.  The components are easy to set-up and use, and the RF2500T target board has very low power consumption.  The RF2500T modules use TI’s MSP430 microcontroller, a Chipcon radio, and the SimpliciTI protocol.

ti-sensor-on-lab-board-small ti-rf2500-on-lab-board-small

We powered the RF2500T Target Board without batteries using a 900MHz transmitter and lab boards with a Powerharvester(TM) module.  The capacitor on the receiving board (shown above left) was first charged to 3V and then the sensor was activated.  The sensor would then run continuously as wireless power was available, and then until the capacitor voltage dropped below the operating threshold.

Later, we used one of the “charge and fire” lab boards from the Lifetime Power(TM) Evaluation and Development Kit (shown above right) to automate the operation.  The P2100 Powerharvester module on the lab board is designed to convert RF energy and store it in a capacitor.  When a voltage threshold is reached on the capacitor, the P2100 switches on its’ output to the sensor at 3.3 volts.  When a lower voltage threshold is reach on the capacitor the output to the sensor is switched off.  The power output to the wireless sensor can be continuous if the received power is greater than the power consumption of the sensor, or the sensor can be operated intermittently when enough energy is accumulated in the capacitor.

The ability for a sensor to support intermittent operation, with variable inactive periods or long sleep periods, and with minimal start-up sequencing and communications handshaking, will provide the farthest range with RF energy harvesting.

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Energy Harvesting to Be Featured at Sensors Expo and Conference

March 16th, 2009

Questex Media Group made the following press release about the upcoming Sensors Expo 2009.

Energy Harvesting will be featured through a Pavilion in the Expo Hall and several conference sessions specific to the topic at The Sensors Expo & Conference, the leading event on sensing technology and solutions. The Expo & Conference will be held Monday, June 8 through Wednesday, June 10 at the Donald E. Stephens Convention Center in Rosemont, IL.

The Energy Harvesting Pavilion is a new area on the show floor providing Energy Harvesting & Power Management solutions that are capable of capturing, converting, storing and delivering energy in a form that can be used to provide the power needed by the system it serves. The Pavilion will also include an Application Showcase Theatre where vendors have scheduled demonstrations and education content around Energy Harvesting & Power Management for all Sensors Expo attendees. Sponsors of the Pavilion include:

Advanced Cerametrics Incorporated: With flexibility and power to match, ACI’s piezo fiber composites are revolutionizing the way engineers think about powering products. ACI piezo composites offer 10X the power generation of other flexible piezo solutions at a fraction of the cost of other piezoelectric composite solutions
Cymbet is the leader in thin film battery technology and energy harvesting power management solutions. Their EnerChip™ provides innovative power storage solutions for many applications including power bridging, permanent power and wireless sensors.
Infinite Power Solutions, Inc. (IPS) is the global leader in developing and manufacturing solid-state, rechargeable thin-film micro-energy storage devices (commonly known as thin-film batteries) for a variety of micro-electronic applications.
MicroStrain® develops and produces innovative, smart, wireless, microminiature displacement, orientation, and force sensors.
Powercast is a leader in wireless power designed for a new class of industrial, commercial and defense applications. Powercast technology enables controllable power delivery over distance for wireless sensors.
Tadiran Batteries lithium thionyl chloride cells are the most powerful and reliable lead-free, RoHS and WEEE compliant batteries in the world, delivering unrivaled performance to power today’s increasingly sophisticated technologies.

“The Sensors Expo & Conference prides itself on offering its attendees the most innovative and newest technologies that will support and advance the industry,” said Debra Brown, event director for Questex Media Group, producers of the event. “Energy Harvesting is a new breakthrough that is having a positive impact on the sensors marketplace and the companies featured in this new Pavilion are key representatives in the field, and we are thrilled to feature them on the Expo floor.”

On Monday, June 8, Randy Frank, President of Randy Frank & Associates, Ltd will present an all day Symposium “Energy Harvesting for Powering Sensor Applications.” Frank will present how to match the energy harvesting technology to specific applications, the importance of the energy/power budget, and the current status of “available” technologies. During his presentation, Frank will discuss the various techniques that exist for converting mechanical or electrical energy, light, or temperature differences into energy for powering sensors including piezoelectric, radio frequency, inductive coupling, wind and solar power. In addition to exploring the various energy harvesting technologies, other system aspects that will be addressed in the session include high efficiency, low-power microcontrollers, wireless connectivity and advanced batteries.

On Wednesday, June 10 there will be several sessions in the Energy Harvesting track, starting with “Wireless Power for Battery- Free Wireless Sensors,” presented by Harry Ostaffe, Director of Marketing, Powercast. “We are excited to be part of this new Energy Harvesting Pavilion and the dedicated conference track. Wireless power based on RF energy harvesting is a unique solution for powering wireless sensors that can be engineered and controlled, enabling predictable lifetime power to sensors for battery recharging or battery-free operation,” said Ostaffe.

Other topics in the conference program include “Wireless & Energy Harvesting Technologies for Energy Inefficient Buildings,” presented by Eugene You, Applications Engineering Manager, EnOcean Inc. and Dan Wright, Electrical Engineer, Leviton. You and Wright will discuss how wireless and energy-harvesting technologies, when combined with sensors, transcend barriers commonly associated with retro-fitting buildings with modern efficiencies. The third session, titled “Where Batteries and Battery-less Merge: Using RF Energy Harvesting to Recharge Batteries for Wireless Devices,” presented by Steve Mesibov, Lead Applications Engineer, Planar Energy Devices. In this session Mesibov will examine a solid-state, thin-film energy storage solution that offers high energy storage density and low leakage rates; how a rechargeable lithium metal, thin-film battery can be powered by RF energy harvesting; and how the battery and RF recharge circuitry compares to the technology of supercapacitors and battery-less energy harvesters.

The 2009 Sensors Conference Program will offer 18 tracks with an expanded focus on data acquisition, data analysis, wireless, M-2-M and communications while continuing to address the challenges of integration and interoperability. Topics that will be covered include Wireless Sensor Networks, MEMS Based System Solutions, Machine Health & Predictive Maintenance, Location-Aware Sensing and much more.

The Expo will bring together the largest showcase of sensing technologies and systems to accomplish industrial automation and achieve more efficient and cost-effective enterprise management. Exhibitors include Silver Sponsor MicroChip Technology, as well as Astyx, Inc., Electrovac, Honeywell, IKONICS Imaging Industrial Solutions, Interplex Engineered Products, Inc., Micronas GmbH, Santest Co., Ltd., Sensor Products, Inc., Siargo Ltd., VXI Technology, X-FAB Semiconductor Foundries AG and others.

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RF Energy Harvesting for Controllable Wireless Power Systems

March 13th, 2009

The slide show here was presented by Charlie Greene of Powercast during the 4th Annual Energy Harvesting Workshop at Virginia Tech in January 2009.

Notice on slide 9 how multiple transmitters of lower aggregate power create a more even field of available RF energy than a single, higher power transmitter.  With this kind of design, a wireless power infrastructure can be created within buildings similar to lighting or Wi-Fi.  Also notice on slide 15 the graphed results of calculations that show how wireless sensors spend a majority of battery energy on sleep mode.  If power was sent wirelessly on a scheduled or periodic basis, sleep mode could be replaced by an inactive state where the sensor is essentially consuming no power.

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