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Design News, February 2013

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Some of the design goals could have been accomplished using a nonstandard radio, and may have even been a cheaper alternative. But one of the original design goals was to have the device sync with standard smartphones. Hence, the move to Bluetooth. Fitbit had worked with Nordic in the past, and had a good rapport with their FAEs, noting that they understood the Fitbit business very well. Park notes, "It came down to the fact that their product met our requirements and from a relationship perspective we felt comfortable with them, and when you deal with a new radio, it's important that the supplier you are working with has a responsive engineering organization in case you have questions or problems." The accelerometer on the Zip is a 3 mm x 3 mm part that can easily be mistaken for one of the passives. Previous generations of the Fitbit devices were built with MSP430 microcontrollers from TI. But the Zip is designed with the ST Cortex M3. Beyond the price and performance benefits, the engineering team enjoyed the code density offered by the 32-bit part (as opposed to the 16-bit MSP430). A lightweight RTOS runs on the processor, mostly for providing some of the basic services. It's a commercial cooperative multitasking OS. A lot of the software for this model had to be written from scratch. That was because the team opted for both a new radio and a new processor. The team estimates that about 90 percent of the code had to be rewritten. The electromechanical integration was fairly challenging due to the device's small size. In addition, it had to be water-sealed, to keep out water and perspiration. As you can see from the figure, there's not a lot of wasted space. Packing everything in was a challenge. — Richard Nass, Brand Director For More Information: Read the full teardown at: http://dn.hotims.com/45100-508 Fitbit Zip: www.fitbit.com Materials & Assembly Flexible Composite Combines Minerals, Thermoplastic 2450Z SerieS BLDC PUMP An Illustration in Innovation A composite that replicates wood's fibrous structure is contending with wood, wood plastic composites, plastics, and metal in a range applications. The innovative 2450Z BLDC pump is perfect for medical and other applications requiring a small lightweight pump with a high performance to weight ratio. materials makers are coming up • Efficient, variable speed brushless DC motor conserves power by matching output to requirement with a variety of ways to make structural composites, from recycled plastic bottles that become weight-bearing elements of heavy load bridges to substituting coconut fibers for traditional ceramic fibers in biocomposite tiles for walls and floors. Now a thermoplastic-mineral composite replicates wood's fibrous structure and is contending with wood, wood plastic composites, plastics, and metal in a range of structural applications. The material is a fully fiberized, molecularly oriented, lineal composite system from Eovations, which is licensing the technology, said Claude Brown, vice president of technology & innovation for Eovations. At present, structural applications include marine uses for docks, pier, seawalls, and pontoons, as well as the cargo decks of vehicles and truck liners. One of the company's primary near-term focuses is the building industry, where it can be used as a Trex replacement for structural framing, as well as for non-structural uses. But it's a bit different from other wood and polymer composites like Trex. The company uses a proprietary extrusion/drawing process to combine mineral particles with a thermoplastic matrix. It's a composite because it combines two distinct materials and phases, Brown said. Half of the composite consists of polymer, mostly polypropylene, and the other 50 percent is a mineral filler. The process first creates a smallscale fiber matrix, and then orients polymer chains within the individual • Lightweight – 6.8 lbs. vs. 9.5 lbs with AC motor • Small footprint – 8.32" x 6.75" x 4.08" • Oil-less design • Maximum flow – 3.3 CFM @ 2200 RPM • Maximum pressure – 35 PSIG For more information on the innovative 2450Z BLDC pump go to gd-thomas.com. Improving Lives through InnovationTM Design News | february 2013 | w w w. d e s i gn n ews.com –35– 850-874_Thomas_2450Z_dn.indd 1 1/17/13 10:12 AM

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