With the widespread use of wearable electronics, portable and flexible energy harvesting devices with a high sensitivity have attracted considerable interest. Herein, an ultrasensitive piezoelectric nanogenerator (PNG) made of a few layers of 2 D‐MoS2‐incorporated electrospun poly(vinlydine fluoride) (PVDF) nanofiber webs (NFW) is described for the first time. As a result of the semiconducting properties and piezoelectric functionalities of 2 D‐MoS2, the resultant piezoelectric performance of PNG can be modulated, which leads to a material suitable for wearable electronics to power devices and to fabricate self‐powered biomedical nanosensors for diagnosis, such as heartbeat monitoring, pressure mapping from footsteps, and speech signal abnormality. We have demonstrated that our PNG has a 70 times improvement in acoustic sensitivity than nanosensors made of neat PVDF NFW and are able to charge a capacitor quickly (e.g., 9 V is charged within 44 s). As a result of the ultrafast charging performance and external low‐impact detection capability of 2 D‐MoS2‐modulated PNG, this paves the way to design cost‐effective self‐powered wearable electronics and robotics.

Superior ferro‐ and piezo‐electret properties in a self‐poled, porous hybrid ferroelectretic polymer nanocomposite film for next‐generation device paradigms is introduced by in situ generation of platinum (Pt) nanoparticles (NPs) embedded in poly(vinylidenefluoride‐co‐hexafluoropropylene) P(VDF–HFP). The cooperative functionality between the self‐polarized β‐phase and the micropores as charge trapping sites is realized by using a simple solvent evaporation method. As a consequence, the resulting film exhibits extraordinary ferroelectretic behavior, as demonstrated by the superior electrical square‐shaped hysteresis loop with large remnant polarization (Pr≈61.7 μC cm−2), piezoelectric charge coefficient (d33∼−686 pC N−1), and ultrahigh dielectric properties (εr=2678, tan δ=0.79 at 1 kHz). A new type of ferroelectretic nanogenerator (FTNG) is fabricated using a flexible hybrid nanocomposite film that effectively converts the applied mechanical energy into electrical energy upon compressive normal stress (e.g., by actuating with a human finger). The 18 V of the open‐circuit output voltage with expected 17.7 μA short‐circuit current are generated from the FTNG under 4 MPa of normal stress amplitude. The high piezoelectric energy conversion efficiency (ηpiezo≈0.2 %) of the FTNG shows that the hybrid polymer nanocomposite film is well suited for the next generation of piezoelectric‐based energy harvesters. The operation of more than 50 blue LEDs, 25 green LEDs, and several capacitors without any subsidiary batteries is demonstrated using the FTNG.

Perhaps the most abundant form of waste energy in our surrounding is the parasitic magnetic noise arising from electrical power transmission system. In this work, a flexible and rollable magneto-mechano-electric nanogenerator (MMENG) based wireless IoT sensor has been demonstrated in order to capture and utilize the magnetic noise. Free standing magnetoelectric composites are fabricated by combining magnetostrictive nickel ferrite (NiFe 2 O 4 ) nanoparticles and piezoelectric polyvinylidene-co-trifluoroethylene (P(VDF-TrFE)) polymer. The magnetoelctric 0-3 type nanocomposites possess maximum magnetoelectric voltage co-efficient (α) of 11.43 mV/cm-Oe. Even, without magnetic bias field 99 % of the maximum value is observed due to self-bias effect. As a result, the MMENG generates peak-to-peak open circuit voltage of 1.4 V, output power density of 0.05 µW/cm 3 and successfully operates commercial capacitor under the weak (⁓ 1.7× 10 -3 T) and low frequency (⁓ 50 Hz) stray magnetic field arising from the power cable of home appliances such as, electric kettle. Finally, the harvested electrical signal has been wirelessly transmitted to a smart phone in order to demonstrate the possibility of position monitoring system construction. This cost effective and easy to integrate approach with tailored size and shape of device configuration is expected to be explored in nextgeneration self-powered IoT sensors including implantable biomedical devices and human health monitoring sensory systems.

In recent years, flexible and sensitive pressure sensors are of extensive interest in healthcare monitoring, artificial intelligence, and national security. In this context, we report the synthetic procedure of a three-dimensional (3D) metal–organic framework (MOF) comprising cadmium (Cd) metals as nodes and isoniazid (INH) moieties as organic linkers (CdI2–INHCMe2) for designing self-polarized ferroelectret-based highly mechano-sensitive skin sensors. The as-synthesized MOF preferentially nucleates the stable piezoelectric β-phase in poly­(vinylidene fluoride) (PVDF) and also gives rise to a porous ferroelectret composite film. Benefiting from the porous structure of 3D MOFs, composite ferroelectret film-based ultrasensitive pressure sensor (mechano-sensitivity of 8.52 V/kPa within 1 kPa pressure range) as well as high-throughput ( power density of 32 μW/cm2) mechanical energy harvester (MEH) has been designed. Simulation-based finite element method (FEM) analysis indicates that the geometrical stress confinement effect within the interpore region of the ferroelectret structure synergistically influences the mechano-electrical property of the MEH. In addition, 143 pC/N (∼4.5 times higher than commercial piezoelectric PVDF films) piezoelectric charge coefficient (d 33) magnitude and superior response time (t r ∼ 8 ms) of this composite ferroelectret film enable the detection of different physiological signals such as coughing, pronunciation, and gulping behavior, making it a promising candidate for early intervention of healthcare, which may play a significant role in accurate alert of influenza and chronic obstructive pulmonary disease (COPD)-related symptoms. In addition, MEH enables the tracking of the subtle pressure change in the wrist pulse, indicating its usefulness in effective mechano-sensitivity. Since the cardiovascular signal is one of the vital parameters that can determine the on-going physiological conditions, the wireless transmission of the detected wrist pulse signal has been demonstrated. All of these features coupled with wireless data transmission indicate the promising application of MOF-assisted composite ferroelectret films in noninvasive real-time remote healthcare monitoring.