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26 The PCB Magazine • January 2015 sub roof or walls, generally substituting for an entire roof, as well as smaller BIPV tiles or slates that substitute for individual or small numbers of conventional shingles, tiles, or slates and can interlace with the conventional material units. The rigidity of these products permits the use of traditional crystalline silicon (c-Si) PV cells and indeed c-Si PV dominates this market. Due to the high production rates and low design com- plexity, this kind of application does not play to the strengths of 3D printed electronics. The move to hybrid and pure electric ve- hicles such as e-cars calls for major weight and volume reduction to reduce cost and increase range (Figure 2). Also needed is replacement of batteries because they need to be replaced well within the life of the vehicle and at great cost. In-mold electronics (IME) are processes by which capacitive sensor switches and other rigid replacements for components with mov- ing parts are made in the molding process for greater reliability, lower cost, reliability, better appearance, space saving, etc. IME is the logical next step for in-mold decorating (IMD). IME is often combined with printed electronics. The high production volumes required by the auto- motive industry are better suited to IME than 3D printed electronics. Printed electronics is the additive form of manufacture of electronic and electrical circuits and components in 2D (i.e., very thin and typi- cally on flexible substrates). It is used for wide- area electronics such as flexible photovoltaics and for large numbers of fairly small circuits. Printed electronics will become a huge busi- ness because it is often lower in cost and/or su- perior in performance to conventional electron- ics, examples of the latter being lighter weight, robustness, fault tolerance and thinness. In ad- dition, some printed displays need no electric- ity unless the image is being changed—useful in signage—and others have unprecedentedly good viewing angle and vibrancy of colours. Metamaterials are artificial materials en- gineered to have properties that may not be found in nature such as negative permittivity, magnetic permeability and refractive index re- sulting in acoustic, optical and electromagnetic capabilities. The honeycomb structure often used lends itself to being a lightweight struc- tural component. The sum of the parts, not the parts themselves, determines how the material behaves. Do not have to be uniform in their structure which makes you able to change the properties of each individual metamaterial al- lowing you to make it go around corners or turn around. Able to make objects invisible to light, microwaves, earthquakes, etc., due to the abil- ity to control of acoustic or electromagnetic ra- diation. Potential applications include remote aerospace applications, sensor detection and infrastructure monitoring, smart solar power management, public safety, radomes, high-fre- quency battlefield communication, terahertz components and lenses for high-gain antennas, improving ultrasonic sensors, and even shield- ing structures from earthquakes and laminar telephoto lenses. Metamaterials are a possible application of 3D printed electronics, particu- larly for longer wavelengths such as microwave or radio. The potential benefits of structural electron- ics are substantial. Making better use of the void spaces in modern vehicles and other ap- plications can clearly result in significant space savings. Fiat believes that cars, with about half Figure 2: Car with printed organic light emitting diode oleD lighting on outside and inside of roof and printed photovoltaics over the outside gener- ating electricity. OPPORTuNITIES FOR 3D PRINTED STRuCTuRAL ELECTRONICS continues FEaturE