Microelectromechanical (MEMS) technology is applied to fabricate artificial bio-mimetic hair-sensors (top). These will be used for studying, characterising and quantifying mechanics and aero/hydrodynamics of the biological counterparts, e.g. cerci.

The hair-sensors developed for operation in air are based on capacitive read-out. A long cylindrical structure (the artificial hair) sits on a membrane that is suspended by torsional springs (middle). Alternating flows, exerting a drag-torque on the hair, cause the membrane to slightly rotate. Electrodes, deposited on top of the membrane, form capacitors with the conducting silicon substrate. Hence, on rotation of the membrane, the left and right capacitance will increase and decrease respectively (or vice verse) and these minute changes in capacitance are measured electrically producing a signal that is proportional to the flow of air (bottom).

Arrays with hairs of dissimilar geometries and embedding will be made so as to obtain variability in frequency response, sensitivity and directionality from a single array. Various implementations ranging from air-embedded hair-sensor arrays to fluid based devices will be fabricated. In addition adaptable MEMS hair-sensors can be dynamically taylored with respect to optimum sensitivity as function of frequency. Mechanical amplification and phase-locking will be much harder to attain but are not ruled out either. In the final phase of the project the MEMS hair-sensors will be used in a larger demonstration set-up in which the knowledge gained in the neuronal research and systems-level research are integrated with the results obtained in this part of the project. Evidently, the overall objective of this part of Cilia is to stretch the mechanical performance of hair-cell based acoustic sensors, including appropriate signal-processing in the mechanical domain.