A transparent bending-insensitive pressure sensor

Abstract

Measuring small normal pressures is essential to accurately evaluate external stimuli in curvilinear and dynamic surfaces such as natural tissues. Usually, sensitive and spatially accurate pressure sensors are achieved through conformal contact with the surface; however, this also makes them sensitive to mechanical deformation (bending). Indeed, when a soft object is pressed by another soft object, the normal pressure cannot be measured independently from the mechanical stress. Here, we show a pressure sensor that measures only the normal pressure, even under extreme bending conditions. To reduce the bending sensitivity, we use composite nanofibres of carbon nanotubes and graphene. Our simulations show that these fibres change their relative alignment to accommodate bending deformation, thus reducing the strain in individual fibres. Pressure sensitivity is maintained down to a bending radius of 80 μm. To test the suitability of our sensor for soft robotics and medical applications, we fabricated an integrated sensor matrix that is only 2 μm thick. We show real-time (response time of ∼20 ms), large-area, normal pressure monitoring under different, complex bending conditions.

Solution‐Processed Bilayer Dielectrics for Flexible Low‐Voltage Organic Field‐Effect Transistors in Pressure‐Sensing Applications

“…Note that the OFET sensor was made on the 175‐µm‐thick PET substrate, which is still thick and thus limits the flexibility and bending performance. If a thinner substrate with better flexibility and stability is used for the highly flexible devices,8 the performance of these low‐voltage OFET‐based pressure sensor could be further improved.…”

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Highly flexible, wearable, and disposable cardiac biosensors for remote and ambulatory monitoring

“…[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] These novel epidermal devices contain soft, conformal sensors and associated circuits embedded in ultrathin encapsulating layers that achieve intimate skin coupling. 25,34 Here, we present a highly flexible epidermal design and clinical implementation of a novel ECG and heart rate logging wearable sensor, henceforth referred to as "WiSP", which is low cost, light-weight (1.2 g), and capable of energy harvesting.…”

Flaw sensitivity of highly stretchable materials

“…Under development are new fields of applications, including tissue regeneration [1], drug delivery [2], artificial muscles [3][4][5], stretchable electronics [5][6][7][8][9], and soft robots [10,11]. Stretchable, transparent, ionic conductors (e.g., hydrogels and ionogels) enable devices of unusual functions, such as transparent loudspeakers [12], artificial skins [13], artificial axons [14,15], and electroluminescence of giant stretchability [16][17][18].…”