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Fiber-in-textile turns clothes into motion sensors By Peter Clarke Cambridge Consultants Ltd. (Cambridge, England) has gone back to some well-known optical sensing methods to develop fiber optic sensors that can be woven in to fabrics that can act turn washable garments into active motion sensors. The XelfleX technology can be used to make robust, washable clothing that can be used to gain body motion information from sports, fitness and medical rehabilitation and for gaming, film making and virtual reality creation. Most attempts at body motion capture in recent times have been addressed by applying inertial motion sensors with wireless communications at key points of the body, usually through wearing a specialized suit. And despite the increased miniaturization of MEMS sensors this has involved cumbersome electronics and electronics that could not be put in the washing machine. The XelfleX uses fiber-optic thread as the sensor. It requires a single electronics pack that clips on to the fiber – in a pocket for example – and communicates wirelessly with a smartphone. The pack disconnects when the garment needs to be washed. XelfleX works on the principle that when a pulse of light is transmitted down an optical fiber, a well-defined amount of light is scattered continuously along its length. Bending the fiber results in increased scattering and reflection, which can then be measured. By integrating the fiber into a closefitting garment, the movement of a joint can change the amount of bending at a defined sensor point in the fiber. Up to 10 sensors are possible along each fiber – with the initial light pulse sent by an LED in the electronics pack. Algorithms then turn the results from the sensors into guidance that users can easily understand, giving feedback on their posture and movement, and coaching them on how to improve. “Our aim was to create wearables that people actually want to wear,” said XelfleX inventor Martin Brock, of Cambridge Consultants. “XelfleX demonstrates the benefits of our crossfertilization of technology between very different sectors – it’s at the intersections between industries that innovation often happens,” said Brock. BASF develops simple 3D image sensor By Peter Clarke Chemicals giant BASF SE (Ludwigshafen, Germany) has developed a single-lens passive optical sensor that can measure distance to an object and thereby 3D position detection and 3D imaging. The company hopes to develop the sensor for a broad range of applications from consumer electronics such as cameras and smartphones to automotive, transportation, medical and machine vision and security and surveillance. The sensor is based on a “new physical effect” BASF’s single-lens passive optical 3D sensor. enabled by the use of specially developed dye-sensitized organic light sensitive chemicals. The effect is complex and described in patent WO 2012110924 A1. It appears to hinge on methods to measure the amount of light falling on a sensor surface and the direction from which it is falling while the light is chopped at two different modulation frequencies and with specific knowledge of the focal depth of lens. One key statement in the patent is that “The sensor signal, given the same total power of the illumination, is dependent on a geometry of the illumination, in particular on a beam cross section of the illumination on the sensor area.” However, it is a novel method that could be simpler than established methods. These are two or multi-lens triangulation to determine 3D position, which is computationally intensive, and time-of-flight measurements of light which depends on a modulated optical source, typically infrared, and is therefore not Prototype 2:0 cameras for position and color detection. Source: BASF suitable for long range measurements where the transmitted beam can be blocked or dissipated by atmospheric effects. The combination of chemistry, materials science and physics has produced a system capable of tracking and imaging objects in three dimensions at about twice the speed of the human eye and brain, BASF claims. The system is able to detect and image over distances ranging from microns to kilometres dictated only by the lens. The sensor works passively and only needs ambient light. In darker surroundings the sensor can be operated with active visible or infrared light sources. The sensor size is comparable to CMOS image sensor chips and so the BASF 3D sensor can be integrated into consumer or professional cameras, mobile phones, tablet computers and could be integrated with a conventional 2D image sensor. With the addition of appropriate software the sensor can be used for purposes beyond imaging, such as autofocus, object, gesture, facial and body expression recognition. www.electronics-eetimes.com Electronic Engineering Times Europe January 2015 39


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