Cricket Inspired Flow-Sensor Arrays

We report current developments in biomimetic flow-sensors based on mechanoreceptive sensory hairs of crickets. These filiform hairs are highly perceptive to low-frequency sound with energy sensitivities close to thermal threshold. In this work we describe hair-sensors fabricated by a combination of sacrificial poly-silicon technology, to form silicon-nitride suspended membranes, and SU8 polymer processing for fabrication of hairs with diameters of about 50 mum and up to 1 mm length. The membranes have thin chromium electrodes on top forming variable capacitors with the substrate allowing for capacitive read-out. Previously these sensors have been shown to exhibit acoustic sensitivity. Based on a hydrodynamic - mechanical interaction model we derive a figure of merit. We present optical measurements on acoustically excited hair-sensors. Experimental data and the derived models are shown to exhibit good correspondence.