A.M.K. Dagamseh

Interfacing of differential-capacitive biomimetic hair flow-sensors for optimal sensitivity

Biologically inspired sensor-designs are investigated as a possible path to surpass the performance of more traditionally engineered designs. Inspired by crickets, artificial hair sensors have shown the ability to detect minute flow signals. This paper addresses developments in the design, fabrication, interfacing and characterization of biomimetic hair flow-sensors towards sensitive high-density arrays. Improvement of the electrode design of the hair sensors has resulted in a reduction of the smallest hair movements that can be measured. In comparison to the arrayed hairs-sensor design, the detection-limit was arguably improved at least twelve-fold, down to 1 mm s–1 airflow amplitude at 250 Hz as measured in a bandwidth of 3 kHz. The directivity pattern closely resembles a figure-of-eight. These sensitive hair-sensors open possibilities for high-resolution spatio-temporal flow pattern observations.

Imaging dipole flow sources using an artificial lateral-line system made of biomimetic hair flow sensors

In Nature, fish have the ability to localize prey, school, navigate, etc., using the lateral-line organ. Artificial hair flow sensors arranged in a linear array shape (inspired by the lateral-line system (LSS) in fish) have been applied to measure airflow patterns at the sensor positions. Here, we take advantage of both biomimetic artificial hair-based flow sensors arranged as LSS and beamforming techniques to demonstrate dipole-source localization in air. Modelling and measurement results show the artificial lateral-line ability to image the position of dipole sources accurately with estimation error of less than 0.14 times the array length. This opens up possibilities for flow-based, near-field environment mapping that can be beneficial to, for example, biologists and robot guidance applications.

Engineering of biomimetic hair-flow sensor arrays dedicated to high-resolution flow field measurements

This paper addresses the latest developments in biomimetic hair-flow sensors towards sensitive high-density arrays. Improving the electrodes design of the hair sensor, using Silicon-on-Insulator (SOI) wafer technology, has resulted in the ability to measure small capacitance changes as caused by minute rotations of single-hair sensors. The detection limit, as measured in a bandwidth of 3 kHz, was about 1 mm/s air-flow amplitude, an enhancement of 52% in comparison to the previous hair-sensor array design. The directivity pattern was improved now closely resembling a figure of eight. These sensors open possibilities for high-resolution flow pattern observations.

Towards high-resolution flow cameras made of artificial hair flow-sensors for flow pattern recognition

Next to image sensors, futures robots will definitely use a variety of sensing mechanisms for navigation and prevention of risks to human life, for example flow-sensor arrays for 3D hydrodynamic reconstruction of the near environment. This paper aims to quantify the possibilities of our artificial hair flow-sensor for high-resolution flow field visualization. Using silicon-on-insulator (SOI) technology with deep trench isolation structures, hair-based flow sensors with separate electrodes arranged in wafer-scale arrays have been successfully fabricated. Frequency Division Multiplexing (FDM) is used to interrogate individual hair elements providing simultaneous real-time flow measurements from multiple hairs. This is demonstrated by reconstructing the dipole fields along different array elements and hence localizing a dipole source relative to the hair array elements.

Imitating the cricket cercal system: The beauty of the beast with a twist of the engineer

MEMS offers exciting possibilities for the fabrication of bioinspired mechanosensors. Over the last years we have been working on cricket inspired hair-sensor arrays for spatio-temporal flow-field observations (i.e flow-camera) and source localization. Whereas making flow-sensors as energy efficient as cricket hair-sensors appears to be a real challenge we have managed to fabricate capacitively interrogated sensors with sub millimeter per second flow sensing thresholds, to use them in lateral line experiments, address them individually while in arrays tracking transient flows, and use nonlinear effects to achieve parametric filtering and amplification. During these developments we have been working in close collaboration with insect biologists, generating a bidirectional flow of information and knowledge, beneficial to both parties. E.g. where the engineering has greatly benefitted from the insights derived from biology and biophysical models, the biologists have been able to take advantage of MEMS structures allowing for the sort of analysis that is hard to do on living material (e.g. the study of viscous coupling between closely spaced hair-sensors).