Nd Doped Zinc Oxide Based Flexible PVDF Polymer Composite for Energy Harvesting and Sensory Application

Flexible Piezoelectric devices have garnered a lot of attention for their potential as energy harvesters and transducers. Zinc Oxide particularly has been doped with different metals and has been incorporated in functional polymers in order to produce flexible piezoelectric devices. In this work, a Neodymium doped Zinc Oxide based flexible piezoelectric energy harvester and sensory device has been developed. For that, neodymium doped zinc oxide has been synthesized using wet chemical co-precipitation method and then has been incorporated in Polyvinylidene Difluoride (PVDF) polymer matrix along with Multiwalled Carbon Nanotubes (MWCNT) to produce flexible piezoelectric films. Silver paste was applied on both sides of the piezoelectric film to produce a compact and flexible piezoelectric energy harvesting device. The piezoelectric outputs of the device were tested at variable tapping frequency ranging from 60 BPM to 240 BPM and pressure (10 to 40 psi). The device was also tested with conventional electronics like bridge rectifiers, capacitors, resistors, LEDs to show its potential as an energy harvester. Compared to other modified ZnO-PVDF based unpoled piezoelectric energy harvesters, this device has shown the most open-circuit output voltage. The device produced the highest piezoelectric open-circuit voltage of 75.8 V. It has also shown an optimum power density of 12.55 μw/cm2 at 1MΩ load impedance. Energy harvesting capacity was further tested by placing the device between the shoe soles during running and jogging. The device also demonstrated uniform signals when it was attached to a part of the body and a specific motion was repeated. This study endorses the potential of Nd-ZnO/PVDF/MWCNT based piezoelectric energy harvester as the most efficient Piezoelectric Nanogenerator (PENG) which shows superior power generation along with self-powered sensory applications

KNN based piezo-triboelectric lead-free hybrid energy films

In recent times, the triboelectric and piezoelectric effects have garnered significant attention towards developing advanced material composites for energy harvesting and sensory applications. In this work, potassium sodium niobate (KNN) based energy films (EF) have been developed to utilize mechanical energy while simultaneously taking advantage of triboelectric and piezoelectric mechanisms. The KNN particles were synthesized using a wet ball milling technique and then incorporated into a polyvinylidene difluoride (PVDF) matrix together with addition of multi wall carbon nanotubes (MWCNT). The film was used to develop a piezoelectric nanogenerator (PENG) fitted with copper electrodes. The piezoelectric output of the film was further tested utilizing copper electrodes, at variable tapping frequency (60 BPM to 240 BPM) and pressure (10–40 psig) were used when activating the pneumatic piston. The open circuit voltage increased with the increase of both tapping frequency and pressure. The maximum piezoelectric output voltage was observed to be 35.3 V while the maximum current was noted as 15.8 µA. The films also showed unique output signals for different types of deformations performed under hand pressure. The film was further utilized to build a piezo-triboelectric hybrid nanogenerator to check its hybrid performance. The maximum output was observed to be 54.1 V and 29.4 µA. This film was integrated with conventional electronic components (bridge rectifiers, resistors, and capacitors) and tested for its ability to harvest energy. The hybrid nanogenerator can charge a 0.1 µF capacitor to 9.4 V in 60 s. The optimum output power for the device was measured to be 0.164 W. The film was further attached with a Kapton film and showed a hybrid output of 113.2 V. This experiment endorsed the potential of the KNN based energy films for multifunctional applications like force, pressure, and motion sensing as well as lead free energy harvesting

Polymer Based Triboelectric Nanogenerator for Cost‐Effective Green Energy Generation and Implementation of Surface‐Charge Engineering

Performance of triboelectric nanogenerators for harvesting mechanical energy from the ambient environment has been limited by structural complexity, cost-effectiveness, and mechanical weakness of materials. Herein, a cost-effective vertical contact separation mode triboelectric nanogenerator using polyethylene (PE) and polycarbonate (PC) in a regular digital versatile disc is reported. This cost-effective nanogenerator with simplified structures is able to generate an open-circuit voltage of 215.3 V and short-circuit current of 80 μA. The effects of the distance of impact and the air gap between the triboelectric layers have also been tested from 3 to 9 cm, and 0.25 to 1 cm, respectively. It is determined that 0.5 cm is the optimal air gap. The nanogenerator is also tested in different real-life scenarios including stresses produced by a moving car, walking, and a rolling skateboard over the nanogenerator. The surfaces of the triboelectric layers are further modified by surface-charge engineering which induced a 460% increase in the output power. These tests reveal a significant electrical response and mechanical stability under stress. In summary, this study demonstrates that the relatively inexpensive PE and PC triboelectric pair has the potential to be used for highly efficient, mechanically robust triboelectric nanogenerators

A bio-inspired visuotactile neuron for multisensory integration

Abstract Multisensory integration is a salient feature of the brain which enables better and faster responses in comparison to unisensory integration, especially when the unisensory cues are weak. Specialized neurons that receive convergent input from two or more sensory modalities are responsible for such multisensory integration. Solid-state devices that can emulate the response of these multisensory neurons can advance neuromorphic computing and bridge the gap between artificial and natural intelligence. Here, we introduce an artificial visuotactile neuron based on the integration of a photosensitive monolayer MoS2 memtransistor and a triboelectric tactile sensor which minutely captures the three essential features of multisensory integration, namely, super-additive response, inverse effectiveness effect, and temporal congruency. We have also realized a circuit which can encode visuotactile information into digital spiking events, with probability of spiking determined by the strength of the visual and tactile cues. We believe that our comprehensive demonstration of bio-inspired and multisensory visuotactile neuron and spike encoding circuitry will advance the field of neuromorphic computing, which has thus far primarily focused on unisensory intelligence and information processing

Flexible Bielectrode-Based Highly Sensitive Triboelectric Motion Sensor: A Sustainable and Smart Electronic Material

The self-powered and autonomous sensors are incredibly important in advanced engineering, especially defence science. The increasing necessity of simple and smart electronics requires to be sustainably flexible, wearable, and waterproof. Triboelectricity has been a widely used mechanism for motion sensing nowadays. Almost all devices based on triboelectricity require contact between two surfaces. Herein, a touchless triboelectric motion sensor for human motion sensing and movement monitoring is developed. The device was primarily fabricated using simple latex (cis-1,4-polyisoprene) structures and copper (electrode materials), which make it a very cost-effective device for sensory applications. The device is tested with specimens of different areas and heights in motion. The maximum output of the device is noted as 12 V at a specimen height of 5 cm. Further different types of human motions are applied in front of the device to ensure low energy sensitivity using triboelectric phenomena. The lightweight smart device precisely provides significant output signals for each movement of the human body which makes the device a prospective medium for motion sensing and movement monitoring which can be applied in the fields of security, energy, and medicine

Development of Color Tunable Piezoelectric Nanogenerators using CsPbX3 Perovskite Nanocrystals Embedded in Poly(D,L-lactide) Membranes

In recent years, inorganic perovskite materials have emerged as a great potential in optoelectronic and flexible nanogenerator applications. In this study, we have synthesized blue to green tunable photoluminescent (PL) inorganic CsPbX3 (X-Cl/Br) perovskite nanocrystals (NCs) utilizing a heat treatment process at a temperature of 150°C. The purity of the NC’s luminescence was analyzed utilizing PL spectroscopy and the pristine blue and green emissions were observed at a 365 nm wavelength under ultraviolet light. Furthermore, the NCs were embedded in a poly(D,L-lactide) (PDLLA) polymer matrix to fabricate flexible blue and green luminous CsPbX3-PDLLA piezoelectric nanogenerators (CPX-PDLLA PENGs). The Fourier-transform infrared spectroscopy characterization of both CPX-PDLLA PENG devices further revealed that perovskite NCs were successfully encapsulated by the PDLLA polymer matrix. The fabricated perovskite based PENGs were tested by hand tapping motion at a 240 beats per minute load frequency to explore the alternating current electrical outputs. The results illustrated that the maximum open circuit voltage and short circuit current obtained for the green PL NCs (g-CPX NCs) incorporated PENG were 1.69 and 1.42 times higher, respectively, in contrast to the blue PL NCs (b-CPX NCs) incorporated PENG. In addition, both b-CPX and g-CPX PDLLA PENGs were tested against a range of resistance and the maximum power output obtained was ~335.44 and ~797.22 W respectively with an active contact area of 31.67 cm2 for all PENGs. The developed flexible g-CPX PDLLA PENG was able to light up 50 commercial light emitting diodes (1.5 V each) indicating the vast promising applications of the PDLLA-CPX PENG as a soft high-performance self-chargeable device

Polymer Based Triboelectric Nanogenerator for Cost‐Effective Green Energy Generation and Implementation of Surface‐Charge Engineering

Performance of triboelectric nanogenerators for harvesting mechanical energy from the ambient environment has been limited by structural complexity, cost-effectiveness, and mechanical weakness of materials. Herein, a cost-effective vertical contact separation mode triboelectric nanogenerator using polyethylene (PE) and polycarbonate (PC) in a regular digital versatile disc is reported. This cost-effective nanogenerator with simplified structures is able to generate an open-circuit voltage of 215.3 V and short-circuit current of 80 μA. The effects of the distance of impact and the air gap between the triboelectric layers have also been tested from 3 to 9 cm, and 0.25 to 1 cm, respectively. It is determined that 0.5 cm is the optimal air gap. The nanogenerator is also tested in different real-life scenarios including stresses produced by a moving car, walking, and a rolling skateboard over the nanogenerator. The surfaces of the triboelectric layers are further modified by surface-charge engineering which induced a 460% increase in the output power. These tests reveal a significant electrical response and mechanical stability under stress. In summary, this study demonstrates that the relatively inexpensive PE and PC triboelectric pair has the potential to be used for highly efficient, mechanically robust triboelectric nanogenerators