Biomimetic Hair Sensor Arrays: From Inspiration To Implementation

In this work, we report on the successful implementation of highly sensitive artificial hair-based flow-sensor arrays for sensing low-frequency air flows. Artificial hair sensors are bio-inspired from crickets’ cercal filiform hairs, one of nature’s best in sensing small air flows. The presented artificial hair sensor arrays aim for sensing performances on a par with the actual insects by means of model-based design optimizations and are fabricated using advanced MEMS technologies.\u

Tunable sensor response by voltage-control in biomimetic hair flow sensors

We present an overview of improvements in detection limit and responsivity of our biomimetic hair flow sensors by electrostatic spring-softening (ESS). Applying a DC-bias voltage to our capacitive flow sensors improves the responsively by up to 80% for flow signals at frequencies below the sensor’s resonance. Application of frequency matched AC-bias voltages allows for tunable filtering and selective gain up to 20 dB. Furthermore, the quality and fidelity of low frequency flow measurements can be improved using a non frequency-matched AC-bias voltage, resulting in a flow detection limit down to 5 mm/s at low (30 Hz) frequencies. The merits and applicability of the three methods are discussed

Optimized biomimetic hair sensor arrays for sensing oscillating air flows

Artificial hair sensor arrays are bio-inspired from flow-sensitive filiform hairs of the crickets, one of nature’s best in sensing small air flows. The presented hair sensor arrays aim to realize higher sensitivities compared to our previous sensor arrays by means of model-based design optimizations and fabricated with advanced MEMS technologies. The artificial hair-sensor arrays display a clear figure-of-eight response and show remarkable sensitivities to oscillating air flows down to 0.85 mm/s surpassing noise levels even at 1 kHz operational bandwidths

Investigating cell-material interactions by monitoring and analysing cell migration

Cell-material interactions can on one hand be characterised by assessing the functional state and or shape of the cells at one or different discrete periods of time, on the other hand by observing cell migration and spreading behaviour. The object of this study was to investigate the migration behaviour of fluorescently labelled cells, and to evaluate the software analysing this migration. In the present study, the behaviour of fibroblasts cells on differently structured surfaces was taken as example. In the first step, the influence of seven different lipophilic dyes (DiI, DiO, DiA, DiD, DiR, PKH2 and PKH26) on cell performance was determined taking biochemical parameters as indices. In the second step, the fluorescence characteristics of these dyes were compared regarding their applicability. In the third step, migration behaviour of DiI-labelled fibroblastic cells on plane and grooved surfaces were monitored and analysed using specific software. Our data suggest that most of the dyes have optimal characteristics for studying cell - cell interactions. Cell migration behaviour regarding migration direction and cell spreading was different on plane and grooved surfaces. It could be shown that computer-based image analysis represents a practical, quick and objective tool to quantify exactly cell migration behaviou

Array of Biomimetic Hair Sensor Dedicated for Flow Pattern Recognition

Flow sensor arrays can be used to extract features from flow fields rather than averaging or providing local measurements provided the sensors in the array structure can be interrogated individually. This paper addresses the latest developments in fabrication and array interfacing of biomimetic artificial air-flow sensors. Hair flow sensors in wafer level arrays have been successfully fabricated using SOI wafers with deep trench isolation structures. Using a Frequency Division Multi¬plexing (FDM) technique, we were able to simultaneously measure flow signals at multiple sensor positions. By virtue of FDM, once signals are retrieved from all individual array elements, spatio-temporal flow patterns can be reconstructed, while few system interconnects are required

Optimization Of Bio-inspired Hair Sensor Arrays

Crickets use a pair of hairy appendages on their abdomen called cerci, each of which contains numerous mechano-receptive filiform hairs. These sensitive hairs can respond even to the slightest air movements, down to 0.03 mm/s, generated by the approaching predators and initiating an escape mechanism in the crickets. Bio-mimicking the cricket cerci, arrays of artificial hair sensors have been successfully fabricated using advanced MEMS techniques. Despite its appreciable performance, the actual cricket filiform hairs outperform artificial hair sensors by several orders in sensitivity. Nevertheless, more careful look at the anatomy and physiology of the cricket cerci provides new directions to be explored with MEMS technologies to realize higher sensitivities on a par with crickets’. This paper aims to provide an overview of comparisons between the actual and artificial hair sensors in terms of sensitivity, structural functionalities and robustness and draws out constructive insights to optimize sensor performance

Effects of serum and serum heat-inactivation on human bone derived osteoblast progenitor cells

Generally, heat inactivated foetal calf serum (FCS) containing media are used for the cultivation of animal and human cells. The role of serum source and serum treatment on the behaviour of cells has long been neglected. The present study was performed to investigate the effects of serum heat inactivation and serum source on trabecular bone derived progenitor cells (HBC). Furthermore, it was investigated in how far these reactions differed from those seen in bone marrow derived mesenchymal progenitor cells (HBMC) cultures. We found that HBC cultures performed differently in the presence of FCS and HS with or without heat inactivation. The reactions similar to some degree those observed in HBMC cultures. The implications of the results on cell-implant surface interaction studies are discusse

Single walled carbon nanotubes (SWCNT) affect cell physiology and cell architecture

Single walled carbon nanotubes (SWCNT) find their way in various industrial applications. Due to the expected increased production of various carbon nanotubes and nanoparticle containing products, exposure to engineered nanoparticles will also increase dramatically in parallel. In this study the effects of SWCNT raw material and purified SWCNT (SWCNT bundles) on cell behaviour of mesothelioma cells (MSTO-211H) and on epithelial cells (A549) had been investigated. The effect on cell behaviour (cell proliferation, cell activity, cytoskeleton organization, apoptosis and cell adhesion) were dependent on cell type, SWCNT quality (purified or not) and SWCNT concentratio

Evaluation of early stage human bone marrow stromal proliferation, cell migration and osteogenic differentiation on μ-MIM structured stainless steel surfaces

It is well established that surface topography greatly affect cell—surface interactions. In a recent study we showed that microstructured stainless steel surfaces characterized by the presence of defined hexagonally arranged hemisphere-like structures significantly affected cell architecture (shape and focal adhesion size) of primary human bone mesenchymal stromal cells. This study aimed at further investigating the influence these microstructures (microcline protruding hemispheres) on critical aspects of cell behaviour namely; proliferation, migration and osteogenic differentiation. As with previously reported data, we used primary human bone mesenchymal stromal cells to investigate such effects at an early stage in vitro. Cells of different patients were utilised for cell migration studies. Our data showed that an increase in cell proliferation was exhibited as a function of surface topography (hemispheres). Cell migration velocity also varied as a function of surface topography on patient specific basis and seems to relate to the differentiated state of the seeded cell population (as demonstrated by bALP positivity). Osteogenic differentiation, however, did not exhibit significant variations (both up and down-regulation) as a function of both surface topography and time in cultur