A Review on Wearable Electrospun Polymeric Piezoelectric Sensors and Energy Harvesters

Abstract

In recent years, wearable sensors and energy harvesters have shown great potential for a wide range of applications in personalized healthcare, robotics, and human-machine interfaces. Among different types of materials used in wearable electronics, piezoelectric materials have gained enormous attention due to their exclusive ability to harvest energy from ambient sources. Piezoelectric materials can be utilized as sensing elements in wearable sensors while harvesting biomechanical energy. Electrospun piezoelectric polymer nanofibers are extensively investigated due to their high flexibility, ease of processing, biocompatibility, and higher piezoelectric property (in contrast to their corresponding cast films). However, as compared to piezoceramic materials, they mostly exhibit relatively lower piezoelectric coefficients. Therefore, considerable efforts have been devoted to improving the piezoelectricity of electrospun polymer nanofibers recently, resulting in significant advances. This review presents a broad overview of these advances including new material, structure designs as well as new strategies to enhance piezoelectricity of electrospun polymer nanofibers. The challenges in achieving high mechanical performance as well as high piezoelectricity are particularly discussed. The main motivation of this review is to examine these challenges and highlight effective approaches to achieving high-performance piezoelectric sensors and energy harvesters for wearable technologies.

Enhanced Piezoelectricity of PVDF-TrFE Nanofibers by Intercalating with Electrosprayed BaTiO3

“…1,29,38 However, with further increases in BTO content (50, 75, and 100%), the β-phase content decreased to 75.65, 71.94, and 68.34%, respectively, which might result from BTO agglomeration within the nanofibers. 1,17,38 XRD was utilized to examine the crystalline structure of the "dispersed PVDF-TrFE + BTO" nanofibers, as shown in Figure 3c. The crystallinity was determined by taking the ratio of the area under the crystalline peaks to the area under the XRD spectrum, which are displayed in Figure 3d.…”

A Review on PVDF Nanofibers in Textiles for Flexible Piezoelectric Sensors

“…Triboelectric sensors typically have high output power, but the design is much more complex and requires a contact separation process involving two surfaces with different charge affinities. 19 Therefore, piezoelectric sensors have attracted much attention for their high sensitivity, simple preparation, and long service life. 20 Piezoelectric materials can generate an electric field while being pressed.…”

“…Although piezoelectric and triboelectric sensors are similar in the capability of higher frequency and a broad range of frequency detection, the two types of sensors are quite different in design. Triboelectric sensors typically have high output power, but the design is much more complex and requires a contact separation process involving two surfaces with different charge affinities . Therefore, piezoelectric sensors have attracted much attention for their high sensitivity, simple preparation, and long service life …”

Effect of cation and anion sizes of additive ionic liquid on the crystal structure of poly(vinylidene fluoride) nanofiber

“…The obtained piezoelectric PVDF nanober mats were used as exible nanogenerators. [5][6][7] In our previous paper, we investigated the effect of the addition of ionic liquid (IL) 1-ethyl-3-methyl-imidazoliun bis(-triuoromethanesulfonyl) imide ([EMI + ][TFSI − ]), on the crystal structure of PVDF nanobers prepared by ES. 8 From this previous study, we found that the addition of [EMI + ][TFSI − ] promoted electroactive phase formation in PVDF nanobers.…”

“…On the other hand, electrospinning (ES) is a known as the processing method, where PVDF is transformed to b-phase dominant state simultaneously with the nanober mat form. 5,6 In the ES process, the PVDF solution is ejected from a spinning nozzle and drawn to a metal collector by applying a high voltage. The solvent in the PVDF solution evaporated during the spinning process, resulting in the formation of a nanober mat.…”