Flexible and Stretchable Piezoelectric Sensor with Thickness-Tunable Configuration of Electrospun Nanofiber Mat and Elastomeric Substrates

Abstract

Here, we developed highly sensitive piezoelectric sensors in which flexible membrane components were harmoniously integrated. An electrospun nanofiber mat of poly(vinylidenefluoride-co-trifluoroethylene) was sandwiched between two elastomer sheets with sputtered electrodes as an active layer for piezoelectricity. The developed sensory system was ultrasensitive in response to various microscale mechanical stimuli and able to perceive the corresponding deformation at a resolution of 1 μm. Owing to the highly flexible and resilient properties of the components, the durability of the device was sufficiently stable so that the measuring performance could still be effective under harsh conditions of repetitive stretching and folding. When employing spin-coated thin elastomer films, the thickness of the entire sandwich architecture could be less than 100 μm, thereby achieving sufficient compliance of mechanical deformation to accommodate artery-skin motion of the heart pulse. These skin-attachable film- or sheet-type mechanical sensors with high flexibility are expected to enable various applications in the field of wearable devices, medical monitoring systems, and electronic skin.

Tuning the piezoelectric and mechanical properties of the AlN system via alloying with YN and BN

“…1,2 An electromechanical (piezoelectric) material requires the best piezoelectric coefficient, while materials for damping high mechanical loads require the high stiffness moduli. 3,4 The high stiffness value is also associated with thermal stability, enabling the use of these materials over a large temperature range.…”

Nanomaterial‐Enabled Wearable Sensors for Healthcare

“…[158] Copyright 2015, Royal Society of Chemistry. Besides the widely used resistive and capacitive mechanisms, progress has been made to develop wearable piezoelectric [22,58,59,159] and triboelectric [160][161][162] pressure sensors. Similar to piezoelectric strain sensors, the piezoelectric pressure sensors detect the applied pressure by measuring the accumulated electric charges.…”

“…Similar to piezoelectric strain sensors, the piezoelectric pressure sensors detect the applied pressure by measuring the accumulated electric charges. Freestanding electrospun PVDFTrFE nanofiber arrays [58] or electrospun PVDF-TrFE nanofiber mat sandwiched between two electrodes [59] were fabricated for piezoelectric pressure sensing. Detection limit as low as 0.1 Pa and high sensitivity of 1.1 V kPa −1 for pressure range between 0.4 and 2 kPa were obtained.…”

“…[170] Copyright 2016, Nature Publishing Group. the strain or pressure induced by radial artery waves at the wrist or finger tip, [44,57,59,103,120,123,126,139,203] jugular venous pulses at the neck [57,59,151] or ankle brachial artery pulses near the foot. [21] Monitoring of respiration rate is critical in diagnosis of many disorders or diseases such as sleep disorders, asthma and anemia.…”

“…Direct spinning of CNTs onto a substrate or into yarns [53][54][55] and electrospinning of nanofibers or NWs were reported to produce fiber-like nanomaterials. [56][57][58][59] In addition, novel direct printing or writing techniques [60,61] such as inkjet printing, [62] gravure printing, [63,64] screen printing, [65][66][67] nozzle jet printing, [26] and direct writing [68,69] enabled the fabrication of wearable sensors that possess complex patterns with high resolution.…”