ENGINEERING

Wide Yet Sensitive

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Science  06 Nov 2009:
Vol. 326, Issue 5954, pp. 773
DOI: 10.1126/science.326_773b

In a displacement force sensor, there is an inherent tradeoff between sensitivity (which requires large deflections to detect weak applied forces) and bandwidth (which requires small deflections to accommodate a wide range of applied forces). Similar tradeoffs apply to sensing in more than one direction while keeping the device compact. Wood et al. sought to optimize these tradeoffs in force sensor design. They fabricated a three-dimensional sensor by folding a laser-patterned Invar sheet, reinforcing it with glass-filled epoxy, and soldering the tabs together. Numerical analysis revealed almost no coupling between the deformation responses along the orthogonal axes. The device proved more sensitive than expected from the modeling studies, because of a lower than expected stiffness, and the bandwidth was also affected by the weight of the adhesive used. The authors demonstrated the sensor's capabilities by simultaneously measuring the lift and drag forces from the flapping wing of a fly-sized robotic insect.

Smart Mater. Struct. 18, 125002 (2009).

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