Stimuli-Responsive Electrospun Piezoelectric Mats of Ethylene-co-vinyl Acetate–Millable Polyurethane–Nanohydroxyapatite Composites

Abstract

Piezoelectric materials have gained interest among materials scientists as body motion sensors and energy harvesters on account of their fast responsiveness and substantial output signals. In this work, piezoelectric polymer mats have been fabricated from ethylene-co-vinyl acetate–millable polyurethane/nanohydroxyapatite (EVA–MPU/nHA) composite systems by employing the electrospinning technique. The ferro-piezoelectric features of the samples were confirmed from the butterfly loops of electrostatic force microscopy (EFM) amplitude signals as well as through the hysteresis curves of the EFM phase recorded with the assistance of dynamic-contact EFM. Piezoelectric responses of the samples to random finger tapping were evaluated after fabricating a simple device prototype connected to an oscilloscope. The efficacy of the mats to generate a voltage in response to activities such as mechanical bending, movement of throat muscles while drinking, movement of elbow joints, air blowing, and so forth has also been investigated. The results suggest the promising possibility of fabricating user-friendly piezoelectric mats out of the EVA–MPU/nHA system for physiological motion-sensing applications.

Stimulus‐Responsive Drug Delivery Nanoplatforms for Osteoarthritis Therapy

“…This will encourage bond breakage in an acidic environment and result in pH-responsive drug release. The second is to change carriers' structure via the protonation of chemical groups (ortho esters, [20,64] Schiff bases, [22,65] acetal/ ketal moieties, [66] hydrazone/oxime linkages, [67,68] silyl ethers [69] and vinyl ethers [70] ) to achieve controllable drug release.…”

Additive manufacturing of smart polymeric composites: Literature review and future perspectives

“…This can be well-defined by using a self-assembling active composite called origami, which entails folding the flat sheet's hinges into the final shape adapted for 4D printing. [238] This technique can be followed in 4D printing to produce practical components like actuators for soft robots, [239,240] motion-sensing products, [241] and soft electronic devices. [8] In addition, 3D/4D printing is closely dependent on the glass transition temperature of the material.…”

Recent Progress of Wearable Piezoelectric Pressure Sensors Based on Nanofibers, Yarns, and Their Fabrics via Electrospinning

“…Other than the above-mentioned electrospun polymers, several other polymer nanofibers demonstrate piezoresponse alone or as composite nanofibers, such as nylon, gelatin, polyurethane, and cellulose. [42,[184][185][186] Odd-numbered nylons have ferroelectric and piezoelectric effects because of abundant hydrogen bonding and dipole orientation by the interaction of amide groups between polymer chains. [187] In addition, nylons have fairly high melting temperature and superior mechanical strength with widely applications in textile engineering.…”

“…In 2021, V H et al utilized electrospinning to prepare piezoelectric nanofiber mats of EVA-MPU/ nanohydroxyapatite (EVA-MPU/nHA) composite system. [185] Through the butterfly circuit of the amplitude signal of the electrostatic force microscope (EFM) and the hysteresis curves recorded by the dynamic contact EFM, the ferroelectric characteristics of the sample are verified. The amplitude increased because of the inverse piezoelectric effect by the applied bias voltage, and the path is shifted upon retracing by virtue of the remnant polarization.…”