Facile Method and Novel Dielectric Material Using a Nanoparticle

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A facile method and novel dielectric material using nanoparticles doped thermoplastic elastomer composite fabric for TENG applications Zhi Zhang, Ying Chen, Dereje Kebebew Debeli, and Jiansheng Guo ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b02133 • Publication Date (Web): 28 Mar 2018 Downloaded from http://pubs.acs.org on March 28, 2018

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ACS Applied Materials & Interfaces

A facile method and novel dielectric material using nanoparticles doped thermoplastic elastomer composite fabric for TENG applications Zhi Zhang, Ying Chen, Dereje Kebebew Debeli, Jian Sheng Guo* Key Laboratory of Textile Science and Technology, Ministry of Education, College of Textiles, Donghua University, Shanghai 201620, People’s Republic of China.

ABSTRACT: The trends towards flexible and wearable electronic devices give rise to the attention of triboelectric nanogenerators (TENGs) which can gather tiny energy from human body motions. However, to accommodate the needs, wearable electronics are still facing challenges for choosing a better dielectric material to improve the performance and practicability. As a kind of synthetic rubber, thermoplastic elastomer (TPE) contains many advantages of lightweight, good flexibility, high tear strength and friction resistance, accompanied by good adhesion with fabrics, which is an optimal candidate of dielectric materials. Herein, a novel NPs doped TPE composite fabric based TENG (TF-TENG) has been developed, which operates based on nanoparticles (NPs) doped thermoplastic elastomer (TPE) composite fabric using a facile coating method. The performances of TENG device are systematically investigated under various thickness of TPE films, NPs kinds and doping mass. After composited with Cu NPs doped TPE film, the TPE composite fabric exhibited superior elastic behavior and

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good bending property, along with excellent flexibility. Moreover, a maximum output voltage of 470 V, current of 24 µA, and power of 12 mW under 3 MΩ can be achieved by applying a force of 60 N on the TF-TENG. More importantly, the TF-TENG can be successfully used to harvest biomechanical energy from human body and provides much more comfort. In general, the TFTENG has great application prospects in sustainable wearable devices owing to its lightweight, flexibility and high mechanical properties.

KEYWORDS: triboelectric nanogenerator (TENG), thermoplastic elastomer (TPE), fabric, nanoparticle, wearable electronics 1. INTRODUCTION In recent years, triboelectric nanogenerators (TENGs) have tremendously attracted long-lasting attentions, which are demonstrated to be a high-efficient approach with low cost to harvest mechanical energy.1-4 One of the most promising prospects of TENGs is the application for flexible and wearable electronics due to their excellent combination with electronic and wearable functions.5-13 In this regard, the intermittent energy from body motions is considered to be one of the most abundant energy sources, especially from human walking, joint motion and muscle stretching, etc.14-18 To accommodate the needs of harvesting energy from human motions, energy supplying devices with the merits of lightweight, flexibility, and high energy/power performance are highly required.13, 19 Thus, converting or integrating the common fabric into TENGs is an ideal choice for wearable and flexible electronics,9, 10, 20-29 since it is mechanically strong and intrinsically flexible, lightweight, shape-adaptive and effectively workable. However, the development of conventional fabrics for TENG applications has been greatly impeded due to limited energy-harvesting efficiencies.


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The key factor to improve output performance is increasing surface charges induced by triboelectrification of TENGs.30 Compared with fabrics, some polymers possess superior triboelectric properties. One facile and effective approach to solving the issue discussed above is to combine fabrics and polymers by coating or dip-coating method, which have gained increasing attention and development. For typical examples, Sangh yo Lee et al. have prepared a textile substrate-based TENG, including nanostructured surface configurations provided by Al nanoparticles (NPs) and polydimethylsiloxane (PDMS).31 Similarly, Yinben Guo et al. have recently reported a textile-based personal energy management device with multilayer-coating structure by encapsulating nylon cloth into PDMS by dip-coating method.30 Wanchul Seung et al. have synthesized ZnO nanorod arrays on a Ag-coated textile followed by coating with PDMS, acting as a triboelectric active layer.32 Likewise, PDMS or silicone rubber coated textiles constructed TENGs with a variety of structures have also been studied.8, 24, 33-35 It is noted that the studies mainly focus on the surface coating of textiles using PDMS or silicone rubber, of which the flexibility and elasticity are remarkably superb among traditional polymers. Nevertheless, PDMS can hardly meet all the requirements for wearable electronics owing to its limited properties and compatibility with clothes especially for thicker materials.36 Moreover, PDMS is a kind of non-recyclable material and cost comparatively high. Given the above, this material is more or less deficient, in spite of the high-power generation efficiency. Then the practicable application of PDMS into human clothing is further limited, which is not the best choice for wearable electronics. Therefore, flexible and wearable electronics are still facing challenges for choosing a better dielectric material to improve their performance and practicability. In this regard, another material complementarily combining better wearability, high power


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generation efficiency and compatibility with fabric is urgently needed. As a kind of synthetic rubber, thermoplastic elastomer (TPE),37 exhibits distinctive characteristics of thermoset rubbers which are dramatically soft and flexible.38 The performance comparison between PDMS and TPE is shown in Table 1, which shows that TPE is lighter, cheaper and softer. Besides, TPE possesses higher tensile strength, tear strength and elasticity, at the same time, excellent insulation and electrostatic property,37 making it an optimal candidate for dielectric materials. Typically, TPE can adhere to the fabric surface with excellent adhesion without adhesives, so that it is facile to be integrated with textile clothes, thus the compatibility can be simultaneously overcome. Moreover, TPE is reusable and can be easily modified by constructing various micro or nano-structures in it, just like PDMS39, 40 and polypropylene (PP)41 which can not only change the surface electrification performance, but also change the dielectric properties of the material, and then affect the electrostatic induction process. ZnO42 and BaTiO343 nanoparticles (NPs) which are of outstanding piezoelectric properties, and graphite particles (GPs),44 carbon nanotubes (CNTs)45 and metal NPs31, 46 which are conductive, have been reported as fillers to improve TENG performance, but without comparative study on two kinds of particles at present. Accordingly, we studied their effect on the TENG performance with two kinds of NPs for contrast, for the first time. Since TPE presents extensive prospects in TENG applications because of excellent properties, a novel NPs doped TPE composite fabric based TENG (TF-TENG) has been developed in this paper. The TF-TENG contains TPE-fabric and pure nylon fabric as two effective dielectric materials, with back-coated with Ag paste as electrodes, and elastic sponges as the spacer supports. Firstly, we report a facile and scalable synthesis of TPE films, for which the film thickness, particle kinds and contents in TPE are systematically studied to improve the output


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Table 1. Performance comparison of PDMS and TPE Performance

Tensile Strength (Mpa)

Specific Gravity (g/cm3)

Durometer Shore (HA)

Cost ($/kg)

Elongation at Break (%)

Tear Strength (kN/m)

Dielectric strength (kV/mm)

Output Performance1

PDMS2

6.7

1.03

43

150

100-300

20-27

19

2.8 W/m2

TPE3

15

0.85

5-10

8

200-500

70-85

37

7.5W/m2(this paper)

performance. For comparison, ZnO and Cu NPs are used to composite with TPE films. The results indicate an optimum condition of TPE concentration of 50% (corresponding thickness is 0.68 mm) and 1.5 g (3 wt%) Cu NPs doping content. A high open-circuit voltage and shortcircuit current of about 600 V and 36 µA, respectively, are observed from 1.5 g (3 wt%) Cu NPs doped TPE based TENG, which is 1.5 times enhanced than pure TPE based TENG. Then the Cu NPs doped TPE film composite fabric (abbreviated as TPE-fabric) are prepared to further improve its wearable performance, by a facile coating method. After the composite process, the TPE-Fabric obtains better elasticity and bending property, and also maintains excellent flexibility. The electric outputs of TPE-fabric constructed TENG (TF-TENG) can reach to 470 V, 26 µA, with the peak power of 12 mW under a resistance of 3 MΩ. Finally, this TF-TENG is attached to human clothing for harvesting human energy. The results show the output voltages and currents are about 350 V and 15 µA for hand beating, 480 V and 22 µA for foot stepping, 65 V and 4 µA for elbow bending, 75V and 6 µA for knee crouching, respectively. Because of good

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Output Performance is for PDMS/TPE-fabric and for reference only.

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PDMS (Sylgard 184 Silicone Elastomer, Dow Corning).

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TPE (Kraiburg, Germany).


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flexibility and bending property, the TF-TENG has great application prospects in sustainable wearable

Figure 1. (a) Schematic illustration of the fabricated TF-TENG. (b) Photographs of TF-TENG (c, d) schematic illustration of the preparation of pure TPE films (c) and NPs doped TPE films and TPE-fabric (d): (i) dissolution and mixing, (ii) or (ii’) shaping by petri dishes, (iii) or (iii’) curing at 80℃ and trimming into a fixed size of 4 cm × 4 cm. devices by gathering human motions. 2. RESULTS AND DISCUSSION 2.1 Structure of the TF-TENG. The construction and photographs of the as-fabricated TFTENG are shown in Figure 1a and b respectively, which is fully flexible and foldable. Basically, the TENG consists of two layers with elastic sponges as the spacer supports. Polyester (PET) fabric is selected as the substrate due to its availability, flexibility, lightweight, and wearing comfort as well. Typically, a layer of nylon fabric as one contact material is adhered to the upper


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substrate with deposited Ag as the electrode. On the lower substrate, NPs doped TPE film is composited with Ag back-coated fabric as the other contact layer. 2.2 Analysis of TPE films and NPs doped TPE films. Before the fabrication of TENGs, a facile strategy was employed to fabricate the TPE based dielectric materials. The fabrication process of the pure TPE films and NPs doped TPE films are schematically depicted in Figure 1c and d and the detailed fabrication process can be found in the Experimental Section.44 After fabrication, the constituent of TPE film was firstly analyzed by FTIR, as shown in Figure S1a. By comparing with the standard infrared spectrogram, it can be seen that the main components of TPE are PP and Styrene-Ethylene-Butylene-Styrene (SEBS). SEBS is one of the extensively used materials which show balanced processability, elasticity, and good thermal stability.47 The crystallization peak in XRD pattern (see Figure S1b) originates from PP, because there is no obvious crystallization of SEBS. According to the triboelectric series (as shown in Table S1),2 TPE stays below the table. Therefore, nylon fabric is chosen as the other contact layer due to the large polarity difference between them, enabling large charge transfer upon contact.48 To characterize the phase of TPE films before and after doped with NPs, X-ray diffraction (XRD) was conducted. Figure 2a and b show a series of XRD patterns for NPs, pure TPE film and NPs doped TPE films with different doping mass. The peak intensities of ZnO NPs and Cu NPs in the doped TPE films get higher as the doping mass increases from 0.05 g (1 wt%) to 0.25 g (5 wt%). The XRD results indicate that the NPs are mixed well into the TPE matrix. The optical photos comparing the TPE films containing different doping mass of ZnO NPs and Cu NPs are shown in Figure 2c and d. As indicated, the corresponding color (i.e. white for ZnO NPs and black for Cu NPs) deepens with the increase of doping concentration. Figure 2e reveals the relationship between TPE concentration and film thickness, which is an absolutely linear


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relationship. Thus the dependence of output performance on the TPE concentration come down to the film thickness. Besides, after doped with NPs (ZnO NPs and Cu NPs), the thickness of

Figure 2. (a) XRD spectras of ZnO NPs and ZnO NPs doped TPE films with different doping mass. (b) XRD spectras of Cu NPs and Cu NPs doped TPE films with different doping mass. Optical photographs of ZnO doped TPE films (c) and Cu NPs doped TPE films (d) with different doping mass. (e) Thickness of pure TPE films with different concentration. (f) Thickness of TPE films after doped with ZnO and Cu NPs. TPE films maintains relatively stable, as shown in Figure 2f. So in the following study, the effect of NPs doping on the film thickness is not taken into account. Subsequently, pure TPE film based TENGs in contact-separation mode were fabricated and measured. To operate, TENGs were interfaced with a customized pressing machine that can provide constant contact force at tunable frequencies under the same pressure of 60 N. The tribo-


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surface areas of these TENGs were all fixed at 4 cm × 4 cm, and the maximum separation distance was fixed at 2 mm.

Figure 3. Output performance of TPE based TENGs with different NPs doping mass. (a) Open-circuit voltages of pure TPE based TENGs. (b) Contrast diagram of open-circuit voltages for pure TPE, ZnO NPs doped TPE, Cu NPs doped TPE based TENGs. Open-circuit voltages (c) and short-circuit currents (d) of ZnO NPs doped TPE film based TENGs. Open-circuit voltages (e) and short-circuit currents (f) of Cu NPs doped TPE film based TENGs. 2.3 Output Performance of TPE film based TENGs. The output performance of asfabricated TENGs are shown in Figure 3. As displayed in Figure 3a, the output voltage increases to the maximum and then decreases with the increase of TPE film thickness. When the TPE


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concentration is 50 wt% (TPE film thickness is 0.68 mm), the open-circuit voltage reaches its maximum, about 410 V. As mentioned above, the pure TPE film of 0.68 mm is chosen to do the NPs doping experiments. For a comparison between the NPs doped TPE and pure TPE film, the doping mass of NPs are investigated systematically to improve output performance. Figure 3c and d present the open-circuit voltages and short-circuit currents of ZnO NPs doped TPE film based TENGs, with different doping mass. As shown Figure 3c, the open-circuit voltage and short-circuit current are relatively constant at first, and then decrease obviously when the mass of ZnO NPs is over 0.1 g (2 wt%). In contrast, the open-circuit voltages and shortcircuit currents of Cu NPs doped TPE film based TENGs are also measured and shown in Figure 3e and f. It is seen that the open-circuit voltage displays a noticeable raise with a topmost value of 600 V at 0.15 g (3 wt%). Afterwards it starts dropping as the doping concentration of Cu NPs increases. There is a same trend of short-circuit current (Figure 3f), where the maximum current reaches up to about 36 µA when the Cu NPs doping mass of 0.15 g (3 wt %). To compare the performance of TENGs more intuitively, the dependence of output voltages on the TPE concentration (or film thickness) and the mass of different NPs is revealed in Figure 3b by a block diagram. It is worth mentioning that a certain amount of Cu NPs can contribute to the improvement of output performance, but ZnO NPs can hardly. To reveal the mechanism of the above phenomena, the resistance of NPs doped TPE films have been tested and plotted in Figure 4a, which indicates that the resistance decreases from 5.22 ×1011 Ω (5.22×105 MΩ, by calculation and shown in Discussion S1 in Supporting Information) to about 8 MΩ with the increase of Cu NPs content from 0 g to 0.15 g and then maintains almost constant till 0.25 g. Compared with the current curves in Figure 4a, the output performance is not merely determined by resistance. Due to the conductivity of Cu NPs, a small amount of Cu NPs


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can improve weak conductivity behavior of TPE films. At this moment, the TF-TENG could be regarded as a flat-panel capacitor.44 The capacitor structure directly affects the maximum charge

Figure 4. (a) The internal resistance and the short-circuit current of the devices with different NPs contents in TPE films. (b) A comparison of output charges of pure TPE, ZnO NPs doped TPE, Cu NPs doped TPE based TENGs. density on the surface of the TPE film, indicating that higher charge density might be obtained. However, a large amount of Cu NPs (more than 0.2 g) might cause their aggregation in the TPE as shown in Figure S3b, which cannot provide a better enhancement of the output performance.44 In contrast, due to serious aggregation and conglutination, ZnO NPs provide a unsuitable distribution in the TPE film, as shown in Figure S2. Figure S2a shows the position with less ZnO NPs distribution, and Figure S2b shows the position with much more distribution, from which we can see that the ZnO have hardly worked. Thus the doping of ZnO NPs can neither form the inner conductive network inside the TPE film, nor remain the electrostatic structure of TPE film. The reason why a slight increase occurs with ZnO NPs less than 0.1 g is due to the influence of surface roughness of ZnO NPs doped TPE film. Experimentally, the output charges of TENGs with different dielectrics are also measured, as shown in Figure 4b. The output charges of ZnO are obviously degraded compared to Cu especially when the doping mass is over then 0.1 g. The maximum charges of pure TPE, ZnO-TPE and Cu-TPE based TENGs are about 102 nC, 102 nC


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and 153 nC respectively. The surface charges on the dielectric film can increase by 50% for the TPE film with Cu NPs content of 0.15 g. These results well demonstrate that NPs doping could change the dielectric properties of TPE film, and then affect the electrostatic induction process. In the work discussed above, the optimum condition is obtained, wherein the TPE film is at 0.68 mm thickness and the doping mass of Cu NPs is 0.15 g (3 wt%). 2.4 Properties of NPs doped TPE film composite fabric (TPE-fabric). Furthermore, to improve the wearability and comfort of Cu NPs doped TPE films and keep them away from direct contact of human skin, a facile strategy was employed to fabricate the composite fabric utilizing NPs doped TPE film coating (detailed in the Experimental section). Therefore a 0.15 g Cu NPs doped TPE-fabric was fabricated, and the photograph showing a good flexural property is shown in Figure 5a. To characterize the morphology of the fabric before and after coated with NPs doped TPE film, FE-SEM and AFM were employed and the results are shown in Figure 5b and c respectively. Before the coating procedure, the nylon fabric displays plain weave structure, interweaving of wefts and warps. The FESEM image showing the surface morphology of TPE film after doped with Cu NPs can be found in Figure S3a. Notably, the AFM image in Figure 5c exhibits nanostructures are uniformly formed on the surface of TPE-fabric, bringing about the improvement of output performance. As for a dielectric material in full-flexible TENG, the capability to withstand harsh stretching and bending is also a significant requirement. As a result, several tensile and flexibility tests were performed. Figure 5d, e and f respectively demonstrate the tensile properties, stretch elasticities and bending properties of pure fabric and Cu NPs doped TPE-fabric. It is worth mentioning that TPE-fabric possesses higher tensile strength and greater tensile elongation, compared with pure fabric (Figure 5d). From the biaxial tensile test under a small force (Figure


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5e), it can be seen that TPE-fabric exhibits a superior elastic recovery. In addition to the excellent tensile and elastic resilience properties, we can also observed that the bending property

Figure 5. Performance measurement of TPE-fabric. (a) A photograph of the flexible and flexural TPE-fabric. (b) FE-SEM image of the pure fabric. (c) AFM image of the surface nanostructures of TPE-fabric. (d) Tensile properties of the Cu doped TPE film, fabric and TPEfabric. (e) Biaxial tensile tests of fabric before and after composite with TPE film. (f) Bending properties of fabric and TPE-fabric. of TPE-fabric and pure fabric are equally matched, as demonstrated in Figure 5f. At the same time, the flexibility of TPE-fabric is barely affected by coating. These test results confirm the excellent flexibility and elasticity which is an integration of merits of fabric and TPE film. 2.5 Working Mechanism of the TF-TENG. The TF-TENG was finally fabricated using nylon fabric and TPE-fabric as two contact layers, as shown in Figure 5a. Generally, the operation of TF-TENG is ascribed to the coupling effect of contact electrification and electrostatic induction.1, 2, 49 Figure 6 schematically presents a cycle of electricity generation process of the TF-TENG for biomechanical energy harvesting. In the initial station, no charge is


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transferred between two electrodes without any motion (Figure 6b). To start, a contact of nylon fabric and TPE-fabric brings about charge transfer at the interface due to their different electron-

Figure 6. Schematic diagrams of the structure (a) and power generation process (b–f) of the TF-TENG. (b) Before contact; (c) fully contacted, the electric charges are generated on dielectric surfaces; (d) releasing, electrons flow from the TPE-fabric electrode to the fabric electrode; (e) fully separated and reaches an electrical equilibrium, no current flows; (f) pressing, electrons flow from the fabric electrode to the TPE-fabric electrode. attracting abilities, resulting in positive charges on the surface of nylon fabric and negative charges on the TPE-fabric (Figure 6c). And then, as the two dielectric layers are leaving away, the induced electrical potential drives the electrons to transfer from the TPE-fabric electrode to the nylon fabric electrode (Figure 6d). The electrons will flow until electrostatic equilibrium state is formed and at the moment the gap distance between the two dielectric layers reaches the maximum (Figure 6e). When the two layers are approaching again under external force,


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electrons flow back from the nylon fabric electrode to the TPE-fabric electrode (Figure 6f) to get an electrostatic equilibrium again (Figure 6c). 2.6 Output Performance of TPE-fabric based TENG (TF-TENG). To evaluate the performance of TF-TENG, the dependence of output current and voltage on the external resistance was systematically investigated at first. It is found that the voltage exhibits an increase trend with the elevation of load resistances, while the current exhibits an inversely proportional relationship, as diagrammed in Figure 7a. Practically, under a force of 60 N, the maximum peak power of 12 mW is obtained under the external resistance of 3 MΩ, with the corresponding voltage and current of about 450 V and 27 µA respectively, as shown in Figure 7b. Figure 7c shows the output charge at the peak is about 165 nC. Therefore, high efficiency is obtained without sacrificing the mechanical flexibility and elasticity of pristine fabrics. The output electric signals under a load resistance of 3 MΩ are demonstrated in Figure 7d to f. Note that the output voltage and current under 3 MΩ reaches as high as 450 V and 26 µA, respectively (Figure 7d and f). As shown in Figure 7e, one cycle of the output signal displays some vibration, which is ascribed to the excellent rebound resilience of TPE film, so that when a force is applied, its deformation and recovery leads to the vibration of waveforms. On the basis of the above results, we have estimated the energy conversion efficiency39, 48, 49for this structure, and the overall efficiency is 16.34%, and direct efficiency could be as high as 29.45% (see details in Discussion S2 in the Supporting Information). To validate the stability of as-fabricated TENG, the output voltage and current were measured for 3000-cycles under continuous operations with the same stimulating condition. According to Figure 7g and h, the output signals exhibit extremely stable results. The stability results indicate a good durability of the TPE-fabric based TENG device, which is crucial to real applications.


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Consecutively, in order to confirm the viability of this full-flexible TENG for harvesting human energy, the TF-TENG was fixed on different positions of body (garments) that always perform maximum movements. All the measurements were under an external resistance of 3 MΩ

Figure 7. Output performance of Cu NPs doped TPE-fabric based TENG (TF-TENG). (a) Dependence of the output current and voltage of TF-TENG on external resistance. (b) Dependence of instantaneous power output of TF-TENG. (c) Transferred charges of the TFTENG under a load of 3 MΩ. (d) Output voltage and (f) output current of TF-TENG under a resistance of 3 MΩ. (e) Output signals for one cycle of output voltage (left) and current (right). (g) Output voltage stability of the TF-TENG. (h) Output current stability of the TF-TENG.


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and results are shown in Figure 8. As can be seen from Figure 8a to d, the output voltages of hand beating, foot stepping, elbow bending and knee crouching are about 350 V, 480 V, 65 V and 75 V, respectively. The corresponding currents are 15 µA, 22 µA, 4 µA and 6 µA, as shown in Figure 8e, indicating a good application of TF-TENG to be incorporated into clothing or garment accessories. Figure 8f reveals that the TF-TENG by foot stepping has the best

Figure 8. Demonstration of the TF-TENG to harvest various biomechanical energies from human body. (a) Output voltage and one cycle voltage by hand tapping on TF-TENG. (b) Output voltage and one cycle voltage by foot stepping on TF-TENG. (c) Output voltage and one cycle voltage by elbow bending on TF-TENG. (d) Output voltage and one cycle voltage by knee crouching on TF-TENG. (e) Output current by applying TF-TENG to different body parts. (f) A comparison of output voltage, current and power for harvesting diverse biochemical energy.


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performance among them. In general, the TF-TENG has great application prospects in sustainable wearable devices owing to its light weight, flexibility and high mechanical properties. 3. CONCLUSIONS In summary, we have fabricated a novel TPE-fabric by a facile coating method, which is proved to be with superb flexibility, high elasticity and tensile strength. This kind of TPE-fabric can be used as an efficient dielectric material due to its good static and mechanical properties. The film thickness, particle kinds and contents in TPE are systematically studied to improve the output performance. It is worth mentioning that a certain amount of Cu NPs can contribute to the improvement of output performance, but ZnO NPs do hardly. A high open-circuit voltage and short-circuit current of about 600 V and 36 µA, respectively, are observed from 1.5 g (3 wt%) Cu NPs doped TPE based TENG, which is 1.5 times enhanced than pure TPE based TENG. Meanwhile, we develop a full-flexible TF-TENG using PET fabric as the substrate, Ag as the electrode, TPE-fabric and nylon fabric as two dielectric materials and elastomer sponges as supporting materials. Under a force of 60 N, the maximum peak power reaches 12 mW under the external resistance of 3 MΩ, with the corresponding voltage and current of about 450 V and 27 µA respectively. This TF-TENG has been demonstrated being capable of harvesting energy from human motions. When this TF-TENG is fixed to different positions of human body (garments), the output voltages and currents of hand beating, foot stepping, elbow bending and knee crouching were about 350 V and 15 µA, 480 V and 22 µA, 65 V and 4 µA, 75V and 6 µA respectively. The results indicate a good viability of produced TF-TENG device. Moreover, the good flexibility and bending property of TENG establishes its applications in clothing and garment accessories. Such a novel dielectric material and fully-flexible TENG produced in this


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work can easily find its application in wearable electronics and push forward a further development. 4. EXPERIMENTAL SECTION 4.1. Preparation of TPE film. Briefly, commercial TPE particles (Kraiburg TC4MGZ, Germany) were dissolved in methylbenzene by magnetic stirring for 1 h to get a stable solution (Figure 1c-i). By controlling the mass of TPE particles, solutions of different concentration (20 wt%, 30wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%) were obtained (Figure 1c-ii). Subsequently, these solutions were transferred into petri dishes and heating at 80 ℃ for 4 h to form the TPE films and finally the films were trimmed to a fixed size of 4 cm × 4 cm. (Figure 1c-iii). 4.2. Preparation of NPs doped TPE film and TPE-fabric. To achieve NPs doped TPE films, zinc oxide (ZnO) and copper (Cu) nanoparticles (NPs) were chosen for comparative experiments. NPs were firstput into TPE solution and mixed by ultrasonic vibration for 1 h to ensure that the NPs were fully dispersed in the solution, and then static defoamed for 8 h (Figure 1d-i). Second, the TPE solution mixed with NPs was transferred into a petri dish to form a thin film (Figure 1d-ii). Third, the petri dish was placed into an oven at 80 ℃ for 4 h to remove all the solvent. Finally, the thin films were taken out of the petri dishes and trimmed to a fixed size (Figure 1d-iii). Typically, TPE film with an optimum doping content was chosen to composite with fabric in order to acquire better wearable properties. For TPE possesses good adhesion with fabric, there was no binder needed, but just need to put the fabric on the bottom of the petri dish before the NPs doped TPE solution was poured in (Figure1d-ii´). 4.3. Characterization and Measurements. Surface morphological observations were performed with a field emission scanning electron microscope (FESEM, Hitachi S-4800, Japan) and an atomic force microscope (Agilent 5500, America). A desk type thickness gauge was used


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to measure the film thickness (China). Fourier Translation Infrared spectroscopy (FTIR) was performed to confirm the characteristic components of TPE on Nicolet 8700 Spectrometer (Thermo Fisher, America). The crystal structures of NPs and NPs doped film were analyzed by X-ray diffraction using Cu Kα radiation (λ = 1.5406 Å). The resistance of the NPs doped TPE film were characterized by a digital multimeter (Agilent 34401A, America). Mechanical properties of TPE-Fabrics were tested by Kawabata Evaluation System-Fabric (KES-FB2S, Japan) and multifunction electronic fabric strength machine (YG026MB testing machine, China). The electrical signals were acquired using a programmable electrometer (Keithley Model 6514, America) and a source meter (Keithley Model 2400, America). ASSOCIATED CONTENT Supporting Information. FTIR spectra of pure TPE film; XRD pattern of pure TPE film; FESEM images of the surface morphologies of ZnO NPs doped TPE film and Cu NPs doped TPE film; Table of triboelectric series (PDF); Discussion about the resistance of NPs doped TPE film; Discussion about the calculation of energy conversion efficiency of TF-TENG. AUTHOR INFORMATION Corresponding Author *E-mail: [email protected] (J.S.G.) ORCID Jian Sheng Guo: 0000-0002-8905-7040 Notes


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The authors declare no competing financial interest. REFERENCES (1) Fan, F. R.; Tian, Z. Q.; Wang, Z. L. Flexible Triboelectric Generator. Nano Energy 2012, 1, 328-334. (2) Wang, Z. L. Triboelectric Nanogenerators as New Energy Technology for Self-Powered Systems and as Active Mechanical and Chemical Sensors. ACS Nano 2013, 7, 9533-9557. (3) Fan, F. R.; Tang, W.; Wang, Z. L. Flexible Nanogenerators for Energy Harvesting and Self-Powered Electronics. Adv. Mater. 2016, 28, 4283-4305. (4) Wu, H.; Huang, Y.; Xu, F.; Duan, Y.; Yin, Z. Energy Harvesters for Wearable and Stretchable Electronics: From Flexibility to Stretchability. Adv. Mater. 2016, 28, 9881-9919. (5) Wang, J.; Li, S.; Yi, F.; Zi, Y.; Lin, J.; Wang, X.; Xu, Y.; Wang, Z. L. Sustainably Powering Wearable Electronics Solely by Biomechanical Energy. Nat. Commun. 2016, 7, 12744. (6) Chen, J.; Huang, Y.; Zhang, N.; Zou, H.; Liu, R.; Tao, C.; Fan, X.; Wang, Z. L. MicroCable Structured Textile for Simultaneously Harvesting Solar and Mechanical Energy. Nature Energy 2016, 1, 16138. (7) Jung, S.; Lee, J.; Hyeon, T.; Lee, M.; Kim, D. H. Fabric-Based Integrated Energy Devices for Wearable Activity Monitors. Adv. Mater. 2014, 26, 6329-6334. (8) Li, Z. L.; Shen, J. L.; Abdalla, I.; Yu, J. Y.; Ding, B. Nanofibrous Membrane Constructed Wearable Triboelectric Nanogenerator for High Performance Biomechanical Energy Harvesting. Nano Energy 2017, 341-348.


21


Page 22 of 28

(9) Zhong, J. W.; Zhang, Y.; Zhong, Q. Z.; Hu, Q. Y.; Hu, B.; Wang, Z. L.; Zhou, J. FiberBased Generator for Wearable Electronics and Mobile Medication. ACS Nano 2014, 8, 62736280. (10) Kim, K. N.; Chun, J.; Kim, J. W.; Lee, K. Y.; Park, J. U.; Kim, S. W.; Wang, Z. L.; Baik, J. M. Highly Stretchable 2D Fabrics for Wearable Triboelectric Nanogenerator under Harsh Environments. ACS Nano 2015, 9, 6394-6400. (11) Cui, N. Y.; Liu, J. M.; Gu, L.; Bai, S.; Chen, X. B.; Qin, Y. Wearable Triboelectric Generator for Powering the Portable Electronic Devices. ACS Appl. Mater. Inter. 2015, 7, 18225-18230. (12) He, X.; Zi, Y.; Guo, H.; Zheng, H.; Xi, Y.; Wu, C.; Wang, J.; Zhang, W.; Lu, C.; Wang, Z. L. A Highly Stretchable Fiber-Based Triboelectric Nanogenerator for Self-Powered Wearable Electronics. Adv. Funct. Mater. 2017, 27, 1604378. (13) Wu, C.; Kim, T. W.; Li, F.; Guo, T. Wearable Electricity Generators Fabricated Utilizing Transparent Electronic Textiles Based on Polyester/Ag Nanowires/Graphene Core–Shell Nanocomposites. ACS Nano 2016, 10, 6449-6457. (14) Niu, S. M.; Wang, X. F.; Yi, F.; Zhou, Y. S.; Wang, Z. L. A Universal Self-Charging System Driven by Random Biomechanical Energy for Sustainable Operation of Mobile Electronics. Nat. Commun. 2015, 6, 8975. (15) Yang, W. Q.; Chen, J.; Zhu, G.; Yang, J.; Bai, P.; Su, Y. J.; Jing, Q. S.; Cao, X.; Wang, Z. L. Harvesting Energy from the Natural Vibration of Human Walking. ACS Nano 2013, 7, 11317-11324.


22

Page 23 of 28 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


(16) Chen, J.; Zhu, G.; Yang, J.; Jing, Q. S.; Bai, P.; Yang, W. Q.; Qi, X. W.; Su, Y. J.; Wang, Z. L. Personalized Keystroke Dynamics for Self-Powered Human-Machine Interfacing. ACS Nano 2015, 9, 105-116. (17) Yi, F.; Lin, L.; Niu, S. M.; Yang, P. K.; Wang, Z. N.; Chen, J.; Zhou, Y. S.; Zi, Y. L.; Wang, J.; Liao, Q. L.; Zhang, Y.; Wang, Z. L. Stretchable-Rubber-Based Triboelectric Nanogenerator and Its Application as Self-Powered Body Motion Sensors. Adv. Funct. Mater. 2015, 25, 3688-3696. (18) Chen, J.; Guo, H.; Liu, G.; Wang, X.; Xi, Y.; Javed, M. S.; Hu, C. A Fully-Packaged and Robust Hybridized Generator for Harvesting Vertical Rotation Energy in Broad Frequency Band and Building up Self-Powered Wireless Systems. Nano Energy 2017, 33, 508-514. (19) Li, J.; Zhang, C.; Duan, L.; Zhang, L. M.; Wang, L. D.; Dong, G. F.; Wang, Z. L. Flexible Organic Tribotronic Transistor Memory for a Visible and Wearable Touch Monitoring System. Adv. Mater. 2016, 28, 106-110. (20) Bai, S.; Zhang, L.; Xu, Q.; Zheng, Y. B.; Qin, Y.; Wang, Z. L. Two Dimensional Woven Nanogenerator. Nano Energy 2013, 2, 749-753. (21) Kim, S. H.; Haines, C. S.; Li, N.; Kim, K. J.; Mun, T. J.; Choi, C.; Di, J.; Oh, Y. J.; Oviedo, J. P.; Bykova, J.; Fang, S.; Jiang, N.; Liu, Z.; Wang, R.; Kumar, P.; Qiao, R.; Priya, S.; Cho, K.; Kim, M.; Lucas, M. S.; Drummy, L. F.; Maruyama, B.; Lee, D. Y.; Lepro, X.; Gao, E.; Albarq, D.; Ovalle-Robles, R.; Kim, S. J.; Baughman, R. H. Harvesting Electrical Energy From Carbon Nanotube Yarn Twist. Science 2017, 357, 773-778. (22) Zeng, W.; Tao, X. M.; Chen, S.; Shang, S. M.; Chan, H. L. W.; Choy, S. H. Highly Durable All-Fiber Nanogenerator for Mechanical Energy Harvesting. Energ. Environ. Sci. 2013, 6, 2631-2638.


23


Page 24 of 28

(23) Song, Y.; Zhang, J.; Guo, H.; Chen, X.; Su, Z.; Chen, H.; Cheng, X.; Zhang, H. AllFabric-Based Wearable Self-Charging Power Cloth. Appl. Phys. Lett. 2017, 111, 073901. (24) Dong, K.; Wang, Y. C.; Deng, J.; Dai, Y.; Zhang, S. L.; Zou, H.; Gu, B.; Sun, B.; Wang, Z. L. A Highly Stretchable and Washable All-Yarn-Based Self-Charging Knitting Power Textile Composed of Fiber Triboelectric Nanogenerators and Supercapacitors. Acs Nano 2017, 11, 9490-9499. (25) Dong, K.; Deng, J.; Zi, Y.; Wang, Y. C.; Xu, C.; Zou, H.; Ding, W.; Dai, Y.; Gu, B.; Sun, B.; Wang, Z. L. 3D Orthogonal Woven Triboelectric Nanogenerator for Effective Biomechanical Energy Harvesting and as Self-Powered Active Motion Sensors. Adv. Mater. 2017, 29, 1702648. (26) Zhao, Z.; Yan, C.; Liu, Z.; Fu, X.; Peng, L. M.; Hu, Y.; Zheng, Z. Machine-Washable Textile Triboelectric Nanogenerators for Effective Human Respiratory Monitoring through Loom Weaving of Metallic Yarns. Adv. Mater. 2016, 28, 10267-10274. (27) Pu, X.; Li, L. X.; Liu, M. M.; Jiang, C. Y.; Du, C. H.; Zhao, Z. F.; Hu, W. G.; Wang, Z. L. Wearable Self-Charging Power Textile Based on Flexible Yarn Supercapacitors and Fabric Nanogenerators. Adv. Mater. 2016, 28, 98-105. (28) Pu, X.; Li, L. X.; Song, H. Q.; Du, C. H.; Zhao, Z. F.; Jiang, C. Y.; Cao, G. Z.; Hu, W. G.; Wang, Z. L. A Self-Charging Power Unit by Integration of a Textile Triboelectric Nanogenerator and a Flexible Lithium-Ion Battery for Wearable Electronics. Adv. Mater. 2015, 27, 2472-2478. (29) Huang, Q.; Wang, D.; Zheng, Z. Textile-Based Electrochemical Energy Storage Devices. Adv. Energy Mater. 2016, 6, 1600783. (30) Guo, Y.; Li, K.; Hou, C.; Li, Y.; Zhang, Q.; Wang, H. Fluoroalkylsilane-Modified TextileBased Personal Energy Management Device for Multifunctional Wearable Applications. ACS Appl. Mater. Inter. 2016, 8, 4676-4683.


24

Page 25 of 28 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


(31) Lee, S.; Ko, W.; Oh, Y.; Lee, J.; Baek, G.; Lee, Y.; Sohn, J.; Cha, S.; Kim, J.; Park, J.; Hong, J. Triboelectric Energy Harvester Based on Wearable Textile Platforms Employing Various Surface Morphologies. Nano Energy 2015, 12, 410-418. (32) Seung, W. Nanopatterned Textile-Based Wearable Triboelectric Nanogenerator. ACS Nano 2016, 9, 3501-3509. (33) Lai, Y. C.; Deng, J.; Zhang, S. L.; Niu, S.; Guo, H.; Wang, Z. L. Single-Thread-Based Wearable and Highly Stretchable Triboelectric Nanogenerators and Their Applications in ClothBased Self-Powered Human-Interactive and Biomedical Sensing. Adv. Funct. Mater. 2017, 27, 1604462. (34) Liu, L. M.; Pan, J.; Chen, P. N.; Zhang, J.; Yu, X. H.; Ding, X.; Wang, B. J.; Sun, X. M.; Peng, H. S. A Triboelectric Textile Templated by a Three-Dimensionally Penetrated Fabric. J. Mater. Chem. A 2016, 4, 6077-6083. (35) Tian, Z.; He, J.; Chen, X.; Zhang, Z.; Wen, T.; Zhai, C.; Han, J.; Mu, J.; Hou, X.; Chou, X.; Xue, C. Performance-Boosted Triboelectric Textile for Harvesting Human Motion Energy. Nano Energy 2017, 39, 562-570. (36) Cui, C.; Wang, X.; Yi, Z.; Yang, B.; Wang, X.; Chen, X.; Liu, J.; Yang, C. Flexible Single-Electrode Triboelectric Nanogenerator and Body Moving Sensor Based on Porous Na2CO3/Polydimethylsiloxane Film. ACS Appl. Mater. Inter. 2018, 10, 3652-3659. (37) Drobny J. G. Handbook of Thermoplastic Elastomers. William Andrew Pub; 2007. (38) Baruffi, F.; Calaon, M.; Tosello, G. Effects of Micro-Injection Moulding Process Parameters on Accuracy and Precision of Thermoplastic Elastomer Micro Rings. Precis. Eng. 2018, 51, 353-361.


25


Page 26 of 28

(39) Peng, J.; Zhang, H.; Zheng, Q.; Clemons, C. M.; Sabo, R. C.; Gong, S.; Ma, Z.; Turng, L.S. A Composite Generator Film Impregnated with Cellulose Nanocrystals for Enhanced Triboelectric Performance. Nanoscale 2017, 9, 1428-1433. (40) Chen, J.; Guo, H.; He, X.; Liu, G.; Xi, Y.; Shi, H.; Hu, C. Enhancing Performance of Triboelectric Nanogenerator by Filling High Dielectric Nanoparticles into Sponge PDMS Film. ACS Appl. Mater. Inter. 2016, 8, 736-744. (41) Gu, G. Q.; Han, C. B.; Tian, J. J.; Lu, C. X.; He, C.; Jiang, T.; Li, Z.; Wang, Z. L. Antibacterial Composite Film-Based Triboelectric Nanogenerator for Harvesting Walking Energy. ACS Appl. Mater. Inter. 2017, 9, 11882-11888. (42) Sun, H.; Tian, H.; Yang, Y.; Xie, D.; Zhang, Y. C.; Liu, X.; Ma, S.; Zhao, H. M.; Ren, T. L. A Novel Flexible Nanogenerator Made of ZnO Nanoparticles and Multiwall Carbon Nanotube. Nanoscale 2013, 5, 6117-6123. (43) Suo, G.; Yu, Y.; Zhang, Z.; Wang, S.; Zhao, P.; Li, J.; Wang, X. Piezoelectric and Triboelectric

Dual

Effects

in

Mechanical-Energy

Harvesting

Using

BaTiO3/

Polydimethylsiloxane Composite Film. ACS Appl. Mater. Inter. 2016, 8, 34335-34341. (44) He, X. M.; Guo, H. Y.; Yue, X. L.; Gao, J.; Xia, Y.; Hu, C. G. Improving Energy Conversion Efficiency for Triboelectric Nanogenerator with Capacitor Structure by Maximizing Surface Charge Density. Nanoscale 2015, 7, 1896-1903. (45) Li, H.; Su, L.; Kuang, S.; Fan, Y.; Wu, Y.; Wang, Z. L.; Zhu, G. Multilayered Flexible Nanocomposite for Hybrid Nanogenerator Enabled by Conjunction of Piezoelectricity and Triboelectricity. Nano Res. 2017, 10, 785-793. (46) Chun, J.; Kim, J. W.; Jung, W.-s.; Kang, C. Y.; Kim, S.-W.; Wang, Z. L.; Baik, J. M. Mesoporous Pores Impregnated with Au Nanoparticles as Effective Dielectrics for Enhancing


26

Page 27 of 28 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


Triboelectric Nanogenerator Performance in Harsh Environments. Energ. Environ. Sci. 2015, 8, 3006-3012. (47) Nehra, R.; Maiti, S. N.; Jacob, J. Analytical Interpretations of Static and Dynamic Mechanical Properties of Thermoplastic Elastomer Toughened PLA Blends. J. Appl. Polym. Sci. 2018, 135, 45644. (48) Wang, S. H.; Lin, L.; Wang, Z. L. Nanoscale Triboelectric-Effect-Enabled Energy Conversion for Sustainably Powering Portable Electronics. Nano Lett. 2012, 12, 6339-6346. (49) Zi, Y. L.; Niu, S. M.; Wang, J.; Wen, Z.; Tang, W.; Wang, Z. L. Standards and Figure-ofMerits for Quantifying the Performance of Triboelectric Nanogenerators. Nat. Commun. 2015, 6, 8376.


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Abstract Graphic


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Facile Method and Novel Dielectric Material Using a Nanoparticle

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