Many animals detect motions in air and water by means of specialized hair-like sensilla that respond with high sensitivity and specificity to the fluid medium motion. For a review see Humphrey and Barth (2007). Examples are the filiform hairs of arthropods such as arachnids, crustaceans and insects, and the vibrissae of seals. In the case of the arthropods the sensors are relatively small (diameter ∼ 5–10 microns, length ∼ 100 – 1000 microns). In the case of seals they are much larger (diameter ∼ 1–2 mm, length ∼ 50 – 150 mm). These sensors are generally clustered in arrays consisting of hairs of different lengths which, for example, in the case of the cricket Grillus bimaculatus and the spider Cupiennius salei can result in frequency fractionation of the motion signals detected. We have designed, fabricated and tested a new type of hybrid sensor array that embodies favorable features taken from the spider trichobothria (such as the flexible membrane structure that supports a trichobotrium) and the seal vibrissae (such as the larger hair length). Each sensor in the array is embedded in a polydimethylsiloxane (PDMS) platform that simulates the spider trichobothrium membrane. Four pairs of capacitors associated with each sensor allow the N-S and E-W detection of fluid motion parallel to the plane of the platform. Sensitivities in the order of few picofarads per 0.5° angular displacements of the sensors are obtained. Measurements and modeling of the sensor array are presented and discussed.

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