Self-Polarization of PVDF Film Triggered by Hydrophilic Treatment for Pyroelectric Sensor with Ultra-Low Piezoelectric Noise

Abstract

Polyvinylidene fluoride (PVDF) films possess multifunctional ability for piezo/pyro/ferroelectronic applications. One critical challenge of the traditional techniques is the complicated fabrication process for obtaining the poled films. In this work, the PVDF film is facilely prepared by the solution cast on hydrophilically treated substrates. The obtained PVDF films exhibit fairly good pyroelectricity comparable to those fabricated by thermal poling, indicating the film is self-polarized. This result is attributed to the hydrogen-bonding-induced orderly arrangement of the first sub-nanolayer at the bottom, which serves as a “seed layer” and triggered alignment of the rest of the film in a layer-by-layer approach. Additionally, to suppress the piezoelectric noise, a pyroelectric sensor with a novel bilayer structure is developed using the as-prepared PVDF film. Compared with the conventional monolayer sensor, the signal-to-noise ratio of the bilayer one is drastically improved to 38 dB from 18 dB. The above results provide great possibilities for achieving a high-performance wearable pyroelectric sensor with reduced cost and simple procedures. Electronic supplementary material The online version of this article (10.1186/s11671-019-2906-1) contains supplementary material, which is available to authorized users.

Design of an Ultrasensitive Flexible Bend Sensor Using a Silver-Doped Oriented Poly(vinylidene fluoride) Nanofiber Web for Respiratory Monitoring

“…Most piezoelectric materials including piezoelectric PVDF film have pyroelectric property, which means their signal could be influenced by temperature fluctuation, limiting their applications. − For instance, it could be difficult to measure the respiratory signal using the piezoelectric PVDF film sensor accurately because of the temperature difference between inhaled and exhaled air. Conversely, the PVDF nanofiber web exhibits relatively low, or almost no, pyroelectricity.…”

“…Most piezoelectric materials including piezoelectric PVDF film have pyroelectric property, which means their signal could be influenced by temperature fluctuation, limiting its applications[29][30][31] . For instance, the piezoelectric PVDF film sensor could be difficult to measure the respiratory signal accurately because of the temperature difference between inhaled and exhaled air.…”

Solution Blow Spinning of Polyvinylidene Fluoride Based Fibers for Energy Harvesting Applications: A Review

“… Various solvent systems used for PVDF-based PEMs and fraction of β-phase obtained [ 18 , 27 , 30 , 42 , 46 , 49 , 70 , 78 , 79 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 ]. …”

High-Performance Paper-Based Capacitive Flexible Pressure Sensor and Its Application in Human-Related Measurement

“…Thanks to their flexibility and ease of integration into curved surfaces like human body, flexible pressure sensors (FPS) have received tremendous attentions and show great potentials for applications in wearable devices [1, 2], electronic skins [3, 4], biomedical systems [5], and human motion detection [6–9]; lots of structures and mechanisms such as field effect transistor [10, 11], capacitor [2, 12], piezoelectric effect [13–16], and piezoresistance effect [17–19] have been proposed to realize FPS; among them, the capacitive FPS becomes increasingly attractive due to its simple structure [20], large dynamic range [21], and good stability [22]. In terms of materials used in FPS, polydimethylsiloxane (PDMS) is an excellent material due to its good flexibility, biomedical compliance with human tissue, and dielectric property, and it is accordingly often used as a structural material in FPS as well as other flexible sensors [23–25]; in capacitive FPS, PDMS was often used as the dielectric layer [20, 26] and electrode substrate [2, 21]. When it comes to the electric conducting layer in FPS, silver nanowires (AgNWs), which have large potential and been widely used in flexible electronics such as solar cells [27–32] and film heaters [33, 34] due to their excellent electrical, optical, and mechanical properties, were often used together with PDMS; for example, Chen et al [35] prepared silver nanowire (AgNWs)/(PDMS) composite films by partly embedding AgNWs in the PDMS layer to create rough surface, and the fabricated sensor device was able to achieve sensitivity three times of that using common metal film electrodes.…”