Polyvinylidene fluoride (PVDF) is among the most attractive piezo-polymers due to its excellent piezoelectricity, lightweight, flexibility, high thermal stability, and chemical resistance. PVDF can exist under different forms of films, membranes, and (nano)fibers, and its piezoelectric property related to its β phase content makes it interesting for energy harvesters and wearable applications. Research investigation shows that PVDF in the form of nanofibers prepared by electrospinning has more flexibility and better air permeability, which make them more suitable for these types of applications. Electrospinning is an efficient technique that produces PVDF nanofibers with a high β phase fraction and crystallinity by aligning molecular dipoles (–CH2 and –CF2) along an applied voltage direction. Different nanofibers production techniques and more precisely the electrospinning method for producing PVDF nanofibers with optimal electrospinning parameters are the key focuses of this paper. This review article highlights recent studies to summarize the influence of electrospinning parameters such as process (voltage, distance, flow rate, and collector), solution (Mw, concentration, and solvent), and ambient (humidity and temperature) parameters to enhance the piezoelectric properties of PVDF nanofibers. In addition, recent development regarding the effect of adding nanoparticles in the structure of nanofibers on the improvement of the β phase is reviewed. Finally, different methods of measuring piezoelectric properties of PVDF nanofibrous membrane are discussed.

Poly(vinyl alcohol) is one of the most attractive polymers with a wide range of uses because of its water solubility, biocompatibility, low toxicity, good mechanical properties, and relatively low cost. This review article focuses on recent advances in poly(vinyl alcohol) electrospinning and summarizes parameters of the process (voltage, distance, flow rate, and collector), solution (molecular weight and concentration), and ambient (humidity and temperature) in order to comprehend the influence on the structural, mechanical, and chemical properties of poly(vinyl alcohol)-based electrospun matrices. The importance of poly(vinyl alcohol) electrospinning in biomedical applications is emphasized by exploring a literature review on biomedical applications including wound dressings, drug delivery, tissue engineering, and biosensors. The study also highlights a new promising area of particles formation through the electrospraying of poly(vinyl alcohol). The limitations and advantages of working with different poly(vinyl alcohol) matrices are reviewed, and some recommendations for the future are made to advance this field of study.

Poly(vinylidene fluoride) (PVDF)-electrosprayed nanofibers have been the subject of much research due to their flexibility and piezoelectric properties compared to other piezoelectrics, for example, ceramics or other polymeric materials. The piezoelectric performance of PVDF is mainly related to the presence of β-phase. This study aims to determine the influence of working and formulation parameters on the generation of β-phase, morphology, and crystal structure of PVDF nanofibers. In addition, this research innovatively analyzes the effect of the dispersion state of PVDF molecular chains in the solvent on the electrospinning results. The morphology and crystal structure of PVDF nanofibers were determined using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). Beadless nanofibers are obtained when the PVDF concentration reaches the semi-diluted regime entangled in dimethylformamide (DMF) or DMF/acetone solution. The optimization of the process parameters (static collector, tip to collector distance—25 cm, flow rate—1 mL/h, applied voltage—20 kV) allows the increase in the β-phase fraction from 68.3% ± 1.2% to 94.5% ± 0.6% for a PVDF concentration of 25 w/v% in a DMF/acetone mixture (2/3 v/v). With these same parameters applied to a rotating collector, it was observed that the piezoelectric performance is at maximum for a maximum β-phase fraction of 90.6% ± 1.1%, obtained for a rotational speed of 200 rpm. The effect of orientation of PVDF nanofibers on piezoelectric properties was quantitatively discussed for the first time; the piezoelectric properties are independent of the alignment of the nanofibers.

A porous electrospun thermoplastic polyurethane (TPU) membrane was designed, fabricated, and functionalized to become a highly sensitive airflow sensor. It is composed of a permeable electrospun nanofibrous structure able to detect and measure low-speed airflow using piezoresistive phenomenon. Our sensory membrane’s SEM images confirmed uniform, homogenous, and beads-free morphology with high porosity. To make this sensor, carbon-based ink was printed on its surface using different patterns to adjust the sensitivity and measurement range. Tensile and cycling tests with electromechanical characterization were performed indicating adaptive mechanical properties, change of resistance under stretch, reproducibility, and repeatability of the sensory membranes. Finally, they can be used in various applications needing high sensitivity and air permeability such as low-speed airflow detection, small multidirectional strains, etc.

Volatile organic compounds (VOCs) have the potential to serve as biomarkers for respiratory diseases such as asthma. Non-invasive respiratory analysis can be used for early detection and disease monitoring. This paper presents the development of a ZnO metal oxide nanofibers sensor as a cost-effective method for detecting NO, which is an asthma biomarker, and NO₂, that can cause asthma. Electrospun metal oxide nanofibers are considered for gas sensor applications due to their unique structural and electrical properties. The results indicate that the amount of zinc acetate and the morphology of the ZnO nanofibers as a sensing medium can affect the sensitivity of the gas sensor. The preparation of electrospinning solutions containing varying amounts of zinc acetate must be carefully considered due to its impact on morphology and thus sensitivity.