Biomechanical and Acoustic Energy Harvesting from TiO2

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Biomechanical and Acoustic Energy Harvesting from TiO2 Nanoparticle Modulated PVDF Nanofiber Made High Performance Nanogenerator Md. Mehebub Alam, Ayesha Sultana, and Dipankar Mandal ACS Appl. Energy Mater., Just Accepted Manuscript • DOI: 10.1021/acsaem.8b00216 • Publication Date (Web): 07 Jun 2018 Downloaded from http://pubs.acs.org on June 7, 2018

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ACS Applied Energy Materials

Biomechanical and Acoustic Energy Harvesting from TiO2 Nanoparticle Modulated PVDF Nanofiber Made High Performance Nanogenerator

Md. Mehebub Alam†, Ayesha Sultana† and Dipankar Mandal†§*

†

Organic Nano-Piezoelectric Device Laboratory, Department of Physics, Jadavpur

University, Kolkata 700032, India §

Institute of Nano Science and Technology (INST), Phase-10, Sector-64, Mohali-160062,

India

*Corresponding author: (D. Mandal) [email protected], [email protected] Tel.: +91 33 2414 6666x2880; fax: +91 33 2413 8917.

1 ACS Paragon Plus Environment

ACS Applied Energy Materials 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ABSTRACT An integrated platform made with piezoelectric nanogenerator (NG) is designed to convert the daily human activities and acoustic vibration into useable electrical energy. The titanium dioxide (TiO2) nanoparticles (NPs) are playing the significant role as external fillers in polyvinylidene fluoride (PVDF) electrospun nanofiber that improves the overall performance of NG. It effectively enhanced the piezoelectric β-phase content (16 % higher F (β)) and mechanical (148 % increment of tensile strength) properties of composite PVDF nanofiber. The superior integration of NG has been demonstrated to generate electricity from human gait. The acoustic sensitivity and concerning mechano-electrical energy conversion efficiency is found to be 26 V Pa-1 and 61 % respectively which is superior in comparison to the reported results. By scavenging the mechanical energy, NG is capable to charge up a 1 µF capacitor, for example, ~ 20 V is within 50 s that ensures its ability to power up commercial LED tape and a LCD screen. Thus, in this work, a high performance piezoelectric NG is presented that has potential application in health care sector and robotic area, in particular to use as a self-powered system.

KEYWORDS.

TiO2 doped PVDF nanofiber, electrospinning, β-phase, wearable and

biomechanical energy scavenging, acoustic nanogenerator


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1. INTRODUCTION A drastic change has been observed in our modern life style since the uses of low powered electronic units are also increasing rapidly.1-3 Moreover, these electronic devices are also shrinking in size and requirement of very low power consumption becomes unique characteristic of the future technology. Several limitations of conventional batteries is driving towards rapid development of self-powered systems, particularly scavenging the mechanical and thermal energy from surrounding enviroment.4,5 For example, batteries have limited lifetime and thus need to be replaced or recharged repeatedly. There are several energies (i.e., solar or thermal energy) that can be harvested but most of them are time and location dependent. In contrast, the existence of mechanical energy with variable frequencies and amplitudes is everywhere regardless of its time dependency. Therefore, piezoelectric and triboelectric NG based mechanical energy harvesting approach has appealed enormous concern.1-6 Noteworthy to mention that human body is generating several kW of energy during daily activities.2 Thus, biomechanical energy harvesting becomes a prime focused of research interest.7-9 Several, approaches have already been initiated for human body energy harvesting from the movements of individual body parts and respiration.10-15 Most of the cases the devices are directly attached to the human skin by belt or, integrated into textile.16-18 However, some drawbacks are associated to harvest the mechanical energy from human activities. For example, the garment or belt needs to be tight enough to catch adequate level of signal that results in an inherent trade-off between comfort and sensitivity. It becomes more uncomfortable in the case of long time application. Thus, the alternative way of the energy harvesting from human activities without compromising with the comfort is one of the prime importance. Recently, energy harvesting from the several random energy sources such as irregular vibrations, noise, wind flow, water flow, raindrops and ultrasonic wave are also carried out by piezoelectric NG.19-23 In contrast, acoustic energy harvesting become



increasingly

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interesting as it is a clean, omnipresent, sustainable energy source.24-26

Recently, utility of acoustic energy harvester for designing the self-powered sound recorder or voiceprint sensor is also demonstrated.27,

28

Thus it is expected that NG can be used in

noisy places where energy harvesting from both of human activities and acoustic noise is feasible. From the material point of view, PVDF has positioned itself as a mostly studied piezoelectric polymer due to its superior ferro-, piezo- and pyroelectricity, apart from flexibility, light-weight, biocompatibility, cost-effectiveness and non-toxicity.29-30 PVDF have polar and nonpolar phases (i.e., α, γ, β, δ and ) and the nonpolar α-phase is the stable phase among them.29 However, β-phase is the most desirable as it exhibits best piezo, pyroand ferroelectric properties.29,

31

Thus, several approach such as mechanical stretching,

thermal annealing or electrical poling are typically attempted to induce β-phase. But, due to several limitations, it may fail to get β-phase containing PVDF in desirable form through these methods.32 On the other hand, electrospinning is a technique that involves mechanical stretching and electrical poling simultaneously and it can easily produce β-phase

in

nanofibers.33,34 It has been shown that electrospun PVDF nanofiber mat exhibits superior flexibility, wearability, air permeability and higher energy conversion efficiency compared to those made of films.35,36 More importantly post poling treatment is not required which is the essential step for device fabrication towards piezoelectric based mechanical energy harvesting application.37 However, improvement of output performance of electrospun fiber based NG is still a challenging task to make it suitable for practical application.7 Therefore, it is expected that the improvement of piezoelectric β-phase content and mechanical property can effectively improve the output performance of the corresponding nanogenerator.38 Very recently, researchers are focused on the doping of semiconducting fillers (e.g., ZnO, MoS2) to improve β-phase content of PVDF fiber.39, 40 It is also noticed that TiO2 is a wide indirect band-gap semiconductor that exhibits prominent thermal and chemical stability, high photo-


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conversion efficiency or photo-stability and most importantly it can make PVDF more suitable for energy harvesting and storage application.41-42 Herein, we have prepared PVDF/TiO2 electrospun fiber mat based flexible and wearable NG to harvest mechanical energy from regular human activities and acoustic vibration. The sensitivity and efficiency for acoustic to electrical energy conversion of the NG exhibit up to 26 V Pa-1 and 61%, respectively. It should be also noted that within 50 second, a 1 µF capacitor is possible to charge up to 20 V that power up a LED tape and LCD screen individually. 2. EXPERIMENTAL SECTION 2.1. Materials PVDF powder (Alfa Aesar), DMF, acetone (Merck Chemical), TiO2 powder (AEROXIDE(R) TiO2 P 25, Evonik Degussa) and Nickel-Copper-Nickel plated fine knit polyester fabric (Coatex Industries, India) of thickness 0.1 ± 0.01 mm with surface resistance 0.05 to 0.1 ohm/sq. 2.2. Preparation of NFs mat 1.2 gm of PVDF powder was dissolved in 10 ml solvent consists of 6 ml DMF and 4 ml acetone. Then 0.5 wt. % of TiO2 NPs of average diameter ~ 20 nm was added into the PVDF solution. A schematic presentation of the electrospinning setup employed in this work is shown in Supporting Information, Figure S1. The prepared PVDF solution was put into a hypodermic syringe and flowed through the needle with feeding rate of 1.5 ml h-1. Once the solution reach to needle tip then it was attracted towards collector (kept at 14 cm apart from the need tip) under influence of applied voltage of 10 kV. Finally, the TiO2 doped PVDF nanofibers (TPNF) are amassed on the collector. A reference mat was also fabricated with pure PVDF nanofiber (PNF).



2.3. Fabrication of NG After the preparation of 250 µm thick electrospun mat, sandwich-like NG was prepared by a simple and scalable method as shown in the schematic presentation in Figure 1. In short, two electrodes (conducting fabrics) of area 60 cm2 are physically attached on the both side of the electrospun mat of length 9.0 cm and breadth 7.5 cm (Figure 1a). The edges are encapsulated by adhesive tape to make a compact structure (Figure 1b). The enlarge view (Figure 1b) demonstrated the cross-sectional view of the NG at the edge.

(a)

(b)

Figure 1. The schematic presentation of NG fabrication. (a) The electrospun fiber mat was sandwiched between two conducting fabric. (b) The edges are encapsulated by adhesive tape. The enlarge cross-sectional view is demonstrating the different layers in the NG at the edges. 2.4. Characterization FT-IR spectroscopy (Bruker, Tensor II) and X-ray diffraction (XRD) (Bruker, D8 Advance diffractometer) studies were carried out to evaluate crystallographic information of the NF mats. Surface morphologies of the NF mats were carried out by Field Emission Scanning Electron Microscope (FE-SEM) (INSPECT F50). Universal testing machine (Tinius Olsen


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H50KS) was employed to testing the mechanical property (stress-strain measurement) of the NF mats. Output voltage was measured by National Instrument (NI) Data acquisition (DAQ) device (NI, USB 6000) which was interfaced with a computer by LabVIEW programme. The short circuit current were recorded by using a picoammeter (Keithley 6485). 3. RESULTS AND DISCUSSION FE-SEM images of fabricated PNF (Figure 2a) and TPNF (Figure 2b) mats depict that randomly oriented fiber are formed. The corresponding histogram profile shows that average fiber diameter of TPNF mat are distinctly decreased in comparison with the PNF mat. This is because of the different in conductivity of the electrospun solutions. This phenomenon could be explained by taking into consideration the entire electrospinning process. It depends on the Coulomb force (F= qE) exerted upon the charge (q) of the surface of the fluid due to the applied electric field (E).

39-40

Since the semiconducting TiO2 NPs comprising PVDF

composite solution must have higher conductivity compared to the neat PVDF solution. Thus, PVDF/TiO2 composite jet experience stronger force in compare to pure PVDF jet under the same applied electric field strength, resulting in decrease of fiber diameter after doping of TiO2 NPs. The reduction of fiber diameter may also causes improvement in mechanical as well as piezoelectric properties of TPNF mat.43 X-ray diffraction peaks appeared at 2θ = 20.9o and 36.9o reveled the electroactive β-phase induction in both the PNF and TPNF mats (Figure 2c and 2d).40, 44 Simulations mechanical and electrical poling during electrospinning process triggered the β-phase in the NF mats. However, after TiO2 doping, diffraction peaks at 2θ = 18.8o and 26.9o corresponding to αphase in PNF (Figure 2c) are almost diminished in TPNF mat (Figure 2d).40, 44 In addition, there are additional peaks at 25.8° and 27.9o in TPNF mat corresponding to the (101) and (110) diffraction peak of TiO2 NPs, respectively. These are direct evidence of existence of TiO2 NPs in TPNF mat. The presence of TiO2 NPs in the TPNF is also shown in the TEM



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image. It is found that the TiO2 NPs are embedded inside the individual nanofiber as shown in Figure S2.

(a)

(b)

2 µm

2 µm

(c)

(d)

(e)

(f) β β

TPNF PNF Powder

α

α α

α α

α

α


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Figure 2. Surface morphology of (a) PNF and (b) TPNF mat, corresponding insets are ensuring the reduction of average fiber diameter due to TiO2 NPs doping.

The XRD

patternof (c) PNF and (d) TPNF mat. (e) FT-IR spectra of PVDF powder, PNF and TPNF mats. (f) Stress-strain curves of the PNF and TPNF mats.

For further confirmation of crystal structures of the NF mats, FT-IR spectra were also carried out and shown in Figure 2e. The PVDF powder that hired for solution preparation, consists of solely mainly α-phase as evident from the peaks at 613, 764, 796, 974, 1018, 1148, 1210 and 1381 cm-1.29 Furthermore, no vibrational peaks at 840 and 1275 cm-1 ensure that there is no β-phase present in the PVDF powder. However, weak vibrational bands at 613 and 764 cm-1 with a newly appeared band at 1275 cm-1 ensured the co-existence of α-phase along with the β-phase in PNF.29, 40 But, the vibrational bands corresponding to α-phase in TPNF mat are almost diminished. Additionally, intensity of 1275 cm-1 band in TPNF becomes stronger that ensures the improvement of β-phase due to TiO2 NPs doping. Thus, a very small amount of TiO2 NPs can improve the β-phase content in PVDF NF mats. The relative proportional of βphase (F(β)) in the NF mats are estimated from equation mentioned in reference 23. It indicates that the TPNF exhibits 93 % of β-phase that is 16 % higher than the PNF mat. This improvement is arises due to the reduction of fiber diameter (Figure 2a-b) and surface chargedipole interaction (Supporting Information, Figure S3).40 Stress-strain curves of PNF and TPNF mats are shown in Figure 2f. Initially, the network like structures of the nanofibers shows a strong opposition against the deformation. Then, slight alignment of the fibers along the tensile force might occurred. After that the mat dimension along the applied stress direction is extended that leads to decrease in cross section (Supporting Information, Figure S4). Thus stress-strain curve shows nonlinear nature up to final breakage point at ultimate strain. The deformation behaviour of fibers mat is also consistent with that previous work.38,



45-47

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However, tensile strength and fracture strain are clearly enhanced for TPNF mat in

comparison to the PNF mat. Young modulus of TPNF mat is found to be 22 N/mm2 which is ~ 129 % higher than that of the PNF mat. Decrease in fiber diameter and the interactions between TiO2 NPs and PVDF lead to improve the mechanical properties. Thus, TPNF mat with higher mechanical strength is anticipated to be more suitable in mechanical energy harvesting application.48

(c)

(b)

(d)

1st fold

2nd fold

Figure 3. (a) Digital photograph, (b) foldability, (c) rollability and (d) wearability of the prepared TPNF mat. The digital photograph of the prepared TPNF mat, its foldability, rollability and wearability are also shown in Figure 3. Thus, TPNF mat is suitable for the fabrication of flexible and wearable nanogenerator. It is found that the NG based on PNF mat exhibited an open-circuit output (peak-to peak) voltage of 7 V (Figure 4a), whereas 11.5 V (Figure 4b) is observed for the TPNF-based NG under compression of a human finger touch of force ~ 5 N in vertical direction. The short-circuit (peak to peak) current under same applied force are found to be 104 nA (Figure 4c) and 176 nA (Figure 4d) from PNF and TPNF mat based NG, respectively. Figure 5 shows the working mechanism of the NG under repeated press and release motion. Due to in situ poling during electrospinning, the dipoles of PVDF are aligned inside the fibers as shown in the Figure 5a (enlarge view).


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(a)

(b)

(c)

(d)

Figure 4. Open-circuit output voltages from the NGs made of (a) PNF and (b) TPNF mat. Output currents from (c) PNF and (d) TPNF based NG under repeated finger touch.

Thus, electrospun fiber mat is a polarized material in which dipoles are aligned along the thickness, establishing a total polarization inside the mat (Figure. 5a). Hence, the current from the electrospun fiber mat is generated due to change in the total polarization that results in the change in surface charge during repetitive pressing and releasing. The change in polarization is mainly arises from change of total dipole moment and thickness of the mat under applied pressure.33 Thus, the application of a compressive stress leads to change in the polarization of the mat and the generated charges are start to flow through external circuit, resulting an electrical signal (Figure 5b). 11 ACS Paragon Plus Environment


(a)

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(c)

(b)

(d)

Figure 5. The working mechanism of the NG at (a) initial state (enlarge view shows that the dipoles are align along the thickness direction), (b) Press and (c) release state. (d) Press and release state resulting positive and negative peak of AC current generated from the NG. After the external stress is removed, the polarization is restored and current start to flow in the opposite direction, resulting an reverse signal (Figure 5c).49 Thus, the NG delivers typical AC signals under periodic press and release motion (Figure 5d). However, the TPNF based NG shows superior piezoelectric throughput due to the overall improved properties of TPNF mat compare to that of the PNF mat as discussed before. Furthermore, the piezoelectric coefficient of the TPNG based NG is found to be 39 pC/N.50 Therefore, the further characterizations are carried out with the TPNF based NG only. The characterization of the biomechanical-electrical energy conversion is inspired by the motion of extremities during movement of the human body for energy harvesting purposes as they are triggered in most of the normal activities including walking.


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(a)

Release

Release

Pressure

NG

(b)

(d)

(c)

Release

Release

Pressure

NG

(f)

(e)



Figure 6. (a) Photographic illustration of arm swings with the mounted NG on a T-shirt in the armpit region. Open-circuit voltage generated by the NG from arm swings during (b) walking and (c) running states. (d) Photographic illustration of leg (foot) swings with the mounted NG on a slipper. Open-circuit voltage generated by the NG from repeated foot on leg (foot) swings during (e) walking and (f) running states.

During walking (or running) there are to and fro motion of foots (z direction) and hands (perpendicular to z direction) and this consideration implies that the to and fro motion of the extremities are only interesting parameters to be considered.51 Here, NG is attached in the armpit region to demonstrate mechanical energy harvesting throughout swinging motion of hand (arm) during walking/running on normal jogging procedure (Figure 6a). The corresponding output voltage of around 1 and 1.5 V during walking and running are shown in Figure 6b and 6c, respectively. During swinging motion, the NG experienced repeated arm pressure and that pressure was transformed into electrical signal. Similar experiment also carried out when the NG is attached onto a slipper for converting the foot pressure into electrical signal. Figure 6d shows swinging motion of legs (foot) during walking or running and the corresponding output voltage of around 1.2 and 1.6 are shown in Figure 6e and 6f, respectively. Multiple NGs are also utilised for harvesting energy from swinging motion of the extremities during running mode. The schematic presentation to demonstrate the attachments of the NGs are shown in Figure 7a. NGs are connected in series to add up for gaining higher voltage value of 2.8 V (Figure 7b). Furthermore, the generated electrical energy was employed to charge up a 1 µF capacitor. The schematic presentation in Figure 7c demonstrating that the NGs are connected in series and output signal from the NGs are rectified by a bridge rectifier. Rectified signals are applied across the capacitor to charge it up (when the key “K” is connected to the point “A”).


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The charged capacitor then employed to lighting a blue led bulb (when the key “K” is connected to the point “B”). The capacitor charging result shows that up to 1.3 V is possible to store within 20 second that is enough to lighting a blue LED bulb. The capacitor charging results are shown in Figure 7d.

(a)

(b)

NG-2

NG-1

NG-3

NG-4

(c)

NG-1

NG-2

NG-3

NG-4

Figure 7. (a) Photographic illustration of arm swings with the mounted NG on a T-shirt (NG1 & NG2) and leg (foot) swings with the mounted NG on a slipper (NG-3 & NG-4). (b) The corresponding output voltage when the NGs are in series connection during running state. (c) Schematic presenting a typical circuit diagram of capacitor charging that powered up a LED by NGs, connected in series. (d) The capacitor charging curve of a 1µF capacitor by the



motion of extremities during running state (inset shows the lighting of LED bulb through charged capacitor). Inset photograph of Figure 7d shows a blue LED at the moment of being lit up by the charged capacitor. We have also attached the NG on the floor and energy harvesting from the weight of the people walking/jumping over it, is examined and shown in Figure 8. These results promise the utility of the NG for designing smart footpath or dance floor. The good stability of the NG is also found as there is no degradation in output voltage after continuous repeated pressing by an imparting machine up to 2500 s as shown in Figure S5.

Walking

Jumping

Figure 8. Output voltage generation from NG subjected to weight of the people during walking and jumping over it. To test the performance of the NG, a different type of experiment was also carried out where the NG is attached to a speaker as shown in Figure 9a for harvesting mechanical energy from the acoustic vibration. It should be noted that there are plenty of similar vibrational sources 16 ACS Paragon Plus Environment

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available throughout, which can be effectively used as an electrical energy source if NG is properly integrated.

(a)

(b)

NG

(c)

(d)

(f) (e)

(f)

Figure 9. (a) Photograph of the NG placed on a speaker for monitoring the sound vibration. (b) Output voltage as a function of different SPL (Inset shows direct lighting of a LED). 17 ACS Paragon Plus Environment


Variations of (c) output voltage, current and (d) power density of the NG across load resistances. (e) Voltage-time curve of the capacitor charging by the NG driven through sound vibration. Inset schematic presenting the typical circuit diagram of capacitor charging for lighting a LED tape by the NG. (f) Snapshots of the LED tape of 100 LED bulbs and a LCD screen (inset) power up by the charged capacitor. In our experiment, when music is on (a pop song was played), NG produces an open-circuit output voltage that also increased with increasing SPL and saturated at 90 dB, shown in Figure 9b and in supporting information, Figure S6. The maximum output peak to peak voltage is found to be 17.5 V indicating that the NG could be useful for monitoring noise pollution and, more interestingly, tiny portable electronic devices might be operated in a selfpowered mode as well. During the presence of music, sound waves are propagate through the air medium and once it reaches to the surface of the NG that cause to vibrate and subsequently converted to electrical signal by the piezoelectric nanofibers present into the NG. Figure 9c presents the variation of output voltage across load resistances (RL). The short circuit current (I) and power (P), related to the output voltage by the relation P= IV = V2/RL is also shown in Figure 9c and 9d, respectively. Output voltage, current and power density (P/A, where A is electrode area) shows the typical nature across the resistances, where voltage gradually increase to a maximum value, current gradually decreases and power density exhibits a peak value. Under sound vibration, the NG is also capable of powering a blue LED, directly connected to it (inset of Figure 9b and video file 1). Furthermore, high acoustic sensitivity make the NG promising to harvest vibrational energy available in the environment, such as wind flow, water waves, and transportation vehicles. The acoustic sensitivity (Sa) of this NG is calculated from the equation mentioned in reference 40. The sensitivity becomes as high as 26 V Pa-1 for acoustic to electrical energy conversion, which is much superior then recently reported results. 40, 52-54 18 ACS Paragon Plus Environment

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A 1 µF capacitor is also successfully charge up, using a typical full wave rectifier circuit. The typical circuit diagram for capacitor charging to power up the LED tape is shown in inset of Figure 9e. It is found that within 50 second the NG charge the capacitor up to 20 V with time constant (τ) 22 s. The storage voltage is enough to power up the LED tape and a LCD screen, shown in Figure 9f and video file 2. The power output of the NG is found to be 4 µW.40 Thus, the overall efficiency (η ) =

×100 % is found to be 61 %, a value which is comparable

to recently published acoustic energy harvesters.55, 56 Noteworthy to mention that here Pin is 6.5 µW.

55

High β-phase content, improved mechanical property and adequate flexibility

make the NG highly sensitive and efficient for acoustic to electrical energy conversion. A drumming cartoon toy is also hired and NG was attached to the top head of a drum (Supporting Information, Figure S7). During drumming, the NG delivers output peak to peak voltage of 2 V (Supporting Information, Figure S7). These merits provide great potential for smart musical instrument, smart toy or robotic application. 4. CONCLUSION We have fabricated an ultrasensitive and highly efficient piezoelectric NG based on TiO2 NPs doped PVDF electrospun mat. It becomes suitable material for piezoelectric NG due to the enhancement of β-phase content, flexibility and mechanical property. Mechanical energy harvesting from human daily activities such as walking, running, jumping is demonstrated. The outstanding electrical output from NG under acoustic vibration is sufficient to directly power a blue LED, charge up capacitor up to 20 V, power up LED tape and LCD screen. This work thus represents a crucial step in building battery-less self-power sensors for biomedicine or robotics application and developing smart footpath, train stations, bus terminals, dance club, musical instrument for smart city designing.



ASSOCIATED CONTENT Supporting Information Supporting Information content schematic of electrospinning setup, FT-IR spectra of the mats in the region of 3040–2960 cm-1, TEM image and digital photo of the TPNF mat, when clipped in universal testing machine (UTM). It also content stability test, the output voltage under different average SPL (40-90 dB) and applications of the NG to harvest energy from a drumming cartoon toy.

NOTES The authors declare no competing financial interest. ACKNOWLEDGMENT We would like to thank for the support from the Science and Engineering Research Board (SERB/1759/2014-15), Govt. of India. Md. Mehebub Alam is supported by the UGC-BSR fellowship (No. P1/RS/191/14). We would also like to thank DST, Govt. of India for developing instrumental facilities under FIST-II programme, Department of Physics, Jadavpur University, Kolkata-700032, India. REFERENCES (1) Wang, Z. L. Self-Powered Nanosensors and Nanosystems. Adv. Mater. 2012, 24, 280– 285. (2) Paradiso, J. A.; Starner, T. Energy Scavenging for Mobile and Wireless Electronics.

Pervasive Comput. 2005, 4, 18. (3) Bhatnagar, V.; Philip, O. Energy Harvesting for Assistive and Mobile Applications.

Energy Sci. Eng. 2015, 3, 153-173.


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(4) Mitcheson, P. D.; Yeatman, E. M.; Rao, G. K.; Holmes, A. S.; Green, T. C. Energy Harvesting from Human and Machine Motion for Wireless Electronic Devices. Proceedings

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Power

Generators

from

Poly(vinylidenefluoride-co-trifluoroethylene)

Electrospun Nano-nonwovens. Nano Energy 2017, 35, 146-153. (56) Sultana, A.; Alam, M. M.; Sadhukhan, P.; Ghorai,U. K.; Das, S.; Middya, T. R.; Mandal, D. Organo-lead Halide Perovskite Regulated Green Light Emitting Poly (vinylidene fluoride) Electrospun Nanofiber Mat and its Potential Utility for Ambient Mechanical Energy Harvesting Application. Nano Energy 2018, 49, 380–392.



Table of contents (TOC) A highly sensitive and efficient NG based of electrospun NF mat is developed. Energy harvesting from human daily activities and acoustic vibration are presented.

ACS Paragon Plus Environment

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Biomechanical and Acoustic Energy Harvesting from TiO2

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