February 05, 2019 Volume 15 Issue 05

Electrical/Electronic News & Products

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Application Note:
Quadcopter propeller torque/thrust testing

The quadcopter's four propellers are designed to work in conjunction with each other to ensure that there are no torque imbalances that could send the vehicle spinning out of control. But just how would a professional developer or hobbyist perform accurate propeller torque and thrust testing? Advanced sensor specialist FUTEK has the answer.
Read the full article.


Engineer's Toolbox: How to choose the right relay

Relays come in a variety of form factors, styles, and technologies. Depending on your application, only one relay type may be suitable. In other cases, multiple relay types may be appropriate. By understanding the strengths and weaknesses of the different relays, you should be able to pick the one that is best suited for the job at hand. National Instruments lays out the options.
Read the full article.


Cool Tools: New Raspberry Pi 3 Model A+

Fans of the extremely popular credit card-sized computer called Raspberry Pi have something new to celebrate. The line of highly customizable base units has expanded with the third-gen A+ board, which brings the latest features and capabilities to a more compact form factor and lower price point -- only 25 bucks (and we have seen this on sale for under 20)!
Read the full article.


Vandal-resistant sealed switches

C&K has just launched its ATP19 and ATP22 series anti-vandal sealed pushbutton switches. The new high-strength, lightweight switches are IP67/IK10 rated, ensuring their suitability for operation in harsh conditions and ability to withstand potential malicious damage. The switches are also corrosion resistant and offer the industry-standard ring-illuminated version in 19-mm and 22-mm diameters.
Learn more.


New inductive-technology position sensors

Novotechnik's TF1 Series touchless linear position sensors overcome issues with legacy magnetostrictive technology. They are unaffected by strong magnetic fields and metal flakes or filings present in a user's environment. The TF1 Series consists of an inductively coupled position marker attached to a moving rod/piece of the user's application that requires a position measurement and the sensor with operational and programming status LEDs. While operating, LEDs indicate whether the sensor is operating and the marker within measuring range or out of range, as well as indicating results of internal diagnostics for valid output from the sensor. Can also measure speed and temperature.
Learn more.


Sensor development kit for power-optimized IoT applications

The RSL10 Sensor Development Kit from ON Semiconductor is designed to provide engineering teams with a comprehensive platform for developing IoT applications with cutting-edge smart sensor technology, enabled by the industry's lowest power Bluetooth Low Energy radio. The kit brings together the highly integrated RSL10 System-in-Package (RSL10 SIP) with a range of advanced low-power sensors from Bosch Sensortec. The development platform provides nine degrees of freedom (DoF) detection and environmental monitoring, including ambient light, volatile organic compounds (VOC), pressure, relative humidity, and temperature. An ultra-low noise digital microphone is also included, along with a user-programmable RGB LED, three programmable push-button switches, and 64 kb of EEPROM. Using the RSL10 Sense and Control mobile application, developers can connect to the RSL10 Sensor Development Kit to monitor sensors and to evaluate the kit's features. The app also supports multiple commercial cloud platforms for uploading sensor data.
Learn more.


EC fans offer spark-proof IP68-ATEX protection for harsh AC applications

Orion Fans has expanded its family of Electronically Commutated (EC) fans to include spark-proof IP68-ATEX-rated versions for applications involving explosive atmospheres or flammable gases. Implementing IP68-ATEX fans into a design decreases the possibility of an explosion or fire. Available in a range of sizes including 60 mm, 120 mm, and 172 mm, the EC IP68-ATEX fans are ideal for a broad range of applications including appliances, commercial and process control, refrigeration, HVAC, electronic enclosures, and cabinets. By maintaining the same interface between the fan and equipment, EC fans can be used as drop-in replacements for equivalent-sized AC fans. The AC input fans utilize a brushless DC motor and incorporate voltage transformation within the motor for significantly lower power consumption. This equates to power savings of up to 50 percent.
Learn more.


Cable assemblies for demanding microwave and RF applications

Intelliconnect has expanded its cable assembly offering for high-frequency and mission-critical applications. Comprised of high-quality cables, connectors, and terminations, the highly reliable RF cable assembly product offering now includes Low Loss, Semi-Rigid, Semi-Flex, and Conformable versions. The microwave and RF cable assembly line is designed for a wide range of applications including marine, medical, mil/aero, microwave communications, oil and gas, rail traction, test and measurement, and more. Available in a variety of sizes and performance specs, these assemblies operate up to 70 GHz and beyond and can be armored internally or externally. Phase matching is also available. Assemblies can be specified as matched sets or built to a specified phase length.
Learn more.


How electronic flow sensors help spread road salt

Salt spreading trucks use a pre-wetting system when ice needs to be removed from roads and the temperatures are too low for direct salt spreading to work. The system sprays salt water onto the road salt as it is being spread to "jump start" the melting process. But how do you monitor the amount of pre-wet salt used?
Read this short, informative blog from Gems Sensors & Controls.


Bend the rules of lighting design: Cut and form LED sheets

VCC is bending the rules of lighting design with its new VentoFlex tiles. The VentoFlex modular lighting system opens up countless ways for architects and lighting designers to make an impact. Available in 12-in. x 12-in. sheets, these innovative LED tiles can be cut and formed around any design element, including rounded corners and tight spaces, without taking up much room at all -- just 0.15 in. (3.81 mm). A pair of scissors is the only tool required to cut VentoFlex tiles to the size and shape you desire. Ten or 15 tiles can be linked together to one driver and dimmer to create thousands of square inches of versatile lighting power!
Learn more about this new and exciting lighting technology.


Slip rings improve Ethernet transmission

The Kuebler Group offers contact and contactless slip rings for reliable Ethernet transmission, achieving higher data rates and greater cycle synchronicity in demanding industrial environments. Application examples include industrial automation, bottling plants, labeling machines, rotary tables, and other processes requiring high transmission rates. The standard Slip Ring SR120 features an innovative three-chamber system and shield to enable parallel, interference-free Ethernet transmission up to 100 Mbps. It boasts a long service life up to 500 million revolutions and a rugged, modular structure that can be expanded up to 20 channels. Another model, the Slip Ring SR160 with integrated Sendix Encoder, provides position information in addition to contactless Ethernet transmission -- either two channels at 100 Mbps multiplexed or one channel at 1 Gbps.
Learn more.


How to convert from hydraulic to electric high-force linear actuators

Machine designers are converting existing linear motion systems from hydraulic to electric due to the technology's many benefits, but the process involves considering the actual force output of the cylinder, the duty cycle, and the motion profile. Specialists at Tolomatic tackle these points. Includes a very informative video.
Read the Tolomatic blog.


Integrate Alexa and more into your product or project

The MATRIX Voice Development Kit from MATRIX Labs aims to lower the barriers to entry for the creation and deployment of Internet of Things (IoT) voice applications. This platform enables users to develop voice recognition and detection projects that utilize Google Assistant or Amazon Alexa -- or any other voice recognition API. This open-source platform for the Raspberry Pi consists of a 3.14-in.-diameter development board, a radial array of 7 MEMS microphones, a Xilinx Spartan6 FPGA with 64 Mbit SDRAM, 18 RGBW LEDs, and 64 GPIO pins. It can also be used as a standalone device with the ESP32. Available from Newark element14.
Learn more from MATRIX Labs.
See purchase options from Newark element14.


Cool Tools: New Raspberry Pi Compute Module 3+

Newark element14 is now shipping the new Raspberry Pi Compute Module 3+ for same-day dispatch. Raspberry Pi Compute Module 3+ delivers the enhanced thermal performance and ease of use of Raspberry Pi 3 Model B+ in a smaller form factor, with a choice of memory variants suitable for a broad range of embedded applications including IoT devices and industrial automation, monitoring, and control systems. Compute Module 3+ simplifies the design process engineers need to undertake when developing a System on Module (SoM) solution into their final product. Engineers do not need to concern themselves with the complexities of interfacing with the BCM2837B0 processer directly and instead can concentrate on designing the interfaces to their own IO board and their application software -- simplicity that fosters rapid development.
Learn more.


360-degree static eliminator is CE, UL, and RoHS certified

EXAIR's new Gen4 Super Ion Air Wipe provides a uniform 360-degree ionized airstream that clamps around a continuously moving part to eliminate static electricity and contaminants. It is ideal for removing dust, particulates, and personnel shocks on pipe, cable, extruded shapes, hose, wire, and more. This engineered product has undergone independent lab tests to certify it meets the rigorous safety, health, and environmental standards to attain the CE and UL marks. It is also RoHS compliant. New design features include a metal armored high-voltage cable to protect against abrasion and cuts, a replaceable emitter point, integrated ground connection, and electromagnetic shielding.
Learn more.


New battery-free 'rectenna' converts Wi-Fi signals to electricity using 2D materials

A device made from flexible, inexpensive materials could power large-area electronics, wearables, medical devices, and more.

By Rob Matheson, MIT

Imagine a world where smartphones, laptops, wearables, and other electronics are powered without batteries. Researchers from MIT and elsewhere have taken a step in that direction, with the first fully flexible device that can convert energy from Wi-Fi signals into electricity that could power electronics.

Devices that convert AC electromagnetic waves into DC electricity are known as "rectennas." The researchers demonstrate a new kind of rectenna, described in a study appearing in Nature Jan. 28, 2019, that uses a flexible radio-frequency (RF) antenna that captures electromagnetic waves -- including those carrying Wi-Fi -- as AC waveforms.

The antenna is then connected to a novel device made out of a two-dimensional semiconductor just a few atoms thick. The AC signal travels into the semiconductor, which converts it into a DC voltage that could be used to power electronic circuits or recharge batteries.

Researchers from MIT and elsewhere have designed the first fully flexible, battery-free "rectenna" -- a device that converts energy from Wi-Fi signals into electricity. [Image: Christine Daniloff]

 

 

 

 

In this way, the battery-free device passively captures and transforms ubiquitous Wi-Fi signals into useful DC power. Moreover, the device is flexible and can be fabricated in a roll-to-roll process to cover very large areas.

"What if we could develop electronic systems that we wrap around a bridge or cover an entire highway, or the walls of our office and bring electronic intelligence to everything around us? How do you provide energy for those electronics?" says paper co-author Tomás Palacios, a professor in the Department of Electrical Engineering and Computer Science and director of the MIT/MTL Center for Graphene Devices and 2D Systems in the Microsystems Technology Laboratories. "We have come up with a new way to power the electronics systems of the future -- by harvesting Wi-Fi energy in a way that's easily integrated in large areas -- to bring intelligence to every object around us."

Promising early applications for the proposed rectenna include powering flexible and wearable electronics, medical devices, and sensors for the Internet of Things. Flexible smartphones, for instance, are a hot new market for major tech firms. In experiments, the researchers' device can produce about 40 microwatts of power when exposed to the typical power levels of Wi-Fi signals (around 150 microwatts). That's more than enough power to light up an LED or drive silicon chips.

Another possible application is powering the data communications of implantable medical devices, says co-author Jesús Grajal, a researcher at the Technical University of Madrid. For example, researchers are beginning to develop pills that can be swallowed by patients and stream health data back to a computer for diagnostics.

"Ideally you don't want to use batteries to power these systems, because if they leak lithium, the patient could die," Grajal says. "It is much better to harvest energy from the environment to power up these small labs inside the body and communicate data to external computers."

All rectennas rely on a component known as a "rectifier," which converts the AC input signal into DC power. Traditional rectennas use either silicon or gallium arsenide for the rectifier. These materials can cover the Wi-Fi band, but they are rigid. And, although using these materials to fabricate small devices is relatively inexpensive, using them to cover vast areas, such as the surfaces of buildings and walls, would be cost-prohibitive. Researchers have been trying to fix these problems for a long time. But the few flexible rectennas reported so far operate at low frequencies and can't capture and convert signals in gigahertz frequencies, where most of the relevant cell phone and Wi-Fi signals are.

To build their rectifier, the researchers used a novel 2D material called molybdenum disulfide (MoS2), which at three atoms thick is one of the thinnest semiconductors in the world. In doing so, the team leveraged a singular behavior of MoS2: When exposed to certain chemicals, the material's atoms rearrange in a way that acts like a switch, forcing a phase transition from a semiconductor to a metallic material. The resulting structure is known as a Schottky diode, which is the junction of a semiconductor with a metal.

"By engineering MoS2 into a 2D semiconducting-metallic phase junction, we built an atomically thin, ultrafast Schottky diode that simultaneously minimizes the series resistance and parasitic capacitance," says first author and EECS postdoc Xu Zhang, who will soon join Carnegie Mellon University as an assistant professor.

Parasitic capacitance is an unavoidable situation in electronics where certain materials store a little electrical charge, which slows down the circuit. Lower capacitance, therefore, means increased rectifier speeds and higher operating frequencies. The parasitic capacitance of the researchers' Schottky diode is an order of magnitude smaller than today's state-of-the-art flexible rectifiers, so it is much faster at signal conversion and allows it to capture and convert up to 10 gigahertz of wireless signals.

"Such a design has allowed a fully flexible device that is fast enough to cover most of the radio-frequency bands used by our daily electronics, including Wi-Fi, Bluetooth, cellular LTE, and many others," Zhang says.

The reported work provides blueprints for other flexible Wi-Fi-to-electricity devices with substantial output and efficiency. The maximum output efficiency for the current device stands at 40 percent, depending on the input power of the Wi-Fi input. At the typical Wi-Fi power level, the power efficiency of the MoS2 rectifier is about 30 percent. For reference, today's rectennas made from rigid, more expensive silicon or gallium arsenide achieve around 50 to 60 percent.

"This very nice teamwork from MIT demonstrates the first real application [of] atomically thin semiconductors for a flexible rectenna for energy harvesting," says Philip Kim, a professor of physics and applied physics at Harvard University whose research focuses on 2D materials. "I am amazed by the innovate approach that the team has set up to utilize the waste energy from RF power around us."

There are 15 other paper co-authors from MIT, Technical University of Madrid, the Army Research Laboratory, Charles III University of Madrid, Boston University, and the University of Southern California.

The team is now planning to build more complex systems and improve efficiency. The work was made possible, in part, by a collaboration with the Technical University of Madrid through the MIT International Science and Technology Initiatives (MISTI). It was also partially supported by the Institute for Soldier Nanotechnologies, the Army Research Laboratory, the National Science Foundation's Center for Integrated Quantum Materials, and the Air Force Office of Scientific Research.

Published February 2019

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