Fluoroalkylsilane-Modified Textile-Based Personal Energy

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Fluoroalkylsilane-Modified Textile-Based Personal Energy Management Device for Multifunctional Wearable Applications Yinben Guo, Kerui Li, Chengyi Hou, Yaogang Li, Qinghong Zhang, and Hongzhi Wang ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.5b11622 • Publication Date (Web): 26 Jan 2016 Downloaded from http://pubs.acs.org on February 1, 2016

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ACS Applied Materials & Interfaces

Fluoroalkylsilane-Modified Textile-Based Personal Energy Management Device for Multifunctional Wearable Applications Yinben Guo a, Kerui Li a, Chengyi Hou a, Yaogang Li b, Qinghong Zhang b*, Hongzhi Wang a* a

State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of

Materials Science and Engineering, Donghua University, Shanghai 201620, People’s Republic of China. b

Engineering Research Center of Advanced Glasses Manufacturing Technology, Ministry of

Education, Donghua University, Shanghai 201620, People’s Republic of China. KEYWORDS: Personal energy management, triboelectric nanogenetator, FAS, heat insulation, wearable heater

ABSTRACT: The rapid development of wearable electronics in recent years has brought increasing energy consumption, making it an urgent need to focus on personal energy harvesting, storage and management. Herein, a textile-based personal energy management device with multilayer-coating structure was fabricated by encapsulating commercial nylon cloth coated with silver nanowires into polydimethylsiloxane using continuous and facile dip-coating method. This multilayer-coating structure can not only harvest mechanical energy from human body motion to

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power wearable electronics but also save energy by keeping people warm without losing heat to surroundings and wasting energy to heat empty space and inanimate objects. Fluoroalkylsilanes (FAS) were grafted onto the surface of the film through one single dip-coating process to improve its energy harvesting performance, which has hardly adverse effect to heat insulation and Joule heating property. In the presence of FAS modification, the prepared film harvested mechanical energy to reach a maximum out-put power density of 2.8 W/m2, charged commercial capacitors and lighted LEDs, showing its potential in powering wearable electronics. Furthermore, the film provided 8 % more thermal insulation than normal cloth at 37 °C and efficiently heated to 40 °C within 4 min when applied the voltage of only 1.5 V due to Joule heating effect. The high flexibility and stability of the film ensure its wide and promise application in wearable field.

1. Introduction Throughout the ages, energy is closely related to our daily life. Especially considering the global energy crisis at present, how to produce, utilize and save energy becomes more and more important. Recently, the emergence of numerous wearable conceptions and products has brought human abundant experiences of entertainment, healthcare, fashion and safety. At the same time, a huge demand of energy from ambient environment for these devices and systems appears and attracts a lot of attentions.1-5 In fact, there is substantial amount of energy being neglected and wasted all over our living environment, like mechanical energy of body motion6-9 and thermal energy of continuous infrared radiation from human body, etc.10 Considering the worldwide vast population, the total amount of energy which can be harvested and saved from each person will be inestimable. Besides studying on varies kinds of clean and sustainable energy sources,11-13 it’s a smart choice to focus on personal energy management, which aims at harvesting widely


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existing energy from human body motion to power small electronics and also saving energy used for keeping people warm. Triboelectric nanogenerators (TENGs) can convert mechanical energy from human body motions into electric power with a coupled effect of triboelectric effect and electrostatic induction.14-18 It is their excellent flexibility, light weight and pollution-free property that make TENGs optimal candidates for powering wearable electronics.19-23 The key factor to improve out-put voltage and current is increasing surface charge induced by triboelectrification of TENGs. On one hand, various kinds of nanostructures like nanoparticles, nanorods, nanowires and nanopatterns were introduced to TENGs to increase the friction and contact area for a higher out-put performance.24-26 However, fabrication and decoration of these nanostructures are commonly complicated and time consuming. Another choice to improve out-put performance from the materials aspect is to increase the triboelectric charge density through material optimization and surface functionalization, like fluorocarbon plasma treatment27 and ionized-air injection.28 Obviously, the approaches of plasma treatment and ionized-air injection were energy consuming and always involved extreme environmental conditions, like vacuum. Keeping warm is one of the most basic human needs. Indoor heating is a common but energyconsuming measure, which not only accounts for over 47% of global energy consumption, but also is highly connected to global warming.10 To save a vast amount of energy, an optimal energy-saving approach which is called “personal thermal management” was reported,4, 29 which included both negatively reducing loss of body heat and positively heating by electricity to raise skin temperature. The concept was realized by coating silver nanowires (AgNWs) onto existing textiles.10 However, when AgNWs cloth directly contact with human skin, its high heat conductivity impairs the heat insulation. Meanwhile, its excellent electric conductivity poses a


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threat to human safety especially when applied voltage. What’s worse, AgNWs are easily peeled off from textile during use. Furthermore, electric heaters also play an important part in thermal therapy for health care. Conventional devices adapted for thermal therapy including heat packs and wraps have often caused discomfort or even scald to their wearers because of their rigidity, heavy weight, nonuniform and uncontrollable heating.30-32 Herein, to integrate multifunction to one single device, we report a textile-based personal energy management (PEM) device which not only harvests mechanical energy from human body to power wearable electronics but also keeps body heat from losing and directly raise body temperature without wasting energy to heat empty space and inanimate objects. The main part of the

PEM

device

is

a

multilayer-coating

structure

with

fluoroalklsilanes

(FAS),

polydimethylsiloxane (PDMS) and silver nanowires (AgNWs) coating on commercial nylon cloth layer by layer, which is abbreviated as FPAN cloth here. For energy harvesting, this FPAN cloth functions as triboelectric material of a TENG. The out-put performance of the TENG is significantly enhanced by the FAS grafted on the surface using one-step facile dip-coating method. The TENG has the highest instantaneous out-put power density (2.8 W/m2), largest short-circuit current (12.6 µA), and highest voltage (590 V). This device drove 247 commercial light-emitting diodes (LEDs) connected in series and charge commercial capacitors (4.7 µF, 22 µF) to voltages of 12 V and 4 V within 500 s, respectively. For saving a large amount of energy from indoor heating, the film can reduce the heat loss by reflecting infrared radiation back toward the body and be raised to 42 °C from ambient temperature (25 °C) within 5 min at a fairly low voltage (1.5 V). Also, the high flexibility and robust wear resistance make sure its potential application in wearable electronic fields.


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2. Experimental Section All chemicals were used as received without further purification. AgNWs dispersed in ethanol with a concentration of 5 mg/ml were purchased from Cold Stones Technology Co., Ltd. The average length and diameter were 25 mm and 50 nm, respectively. Commercial nylon cloth (PA 6) was used as substrate. Aqueous solutions were prepared with ultrapure water (UPW, 18.2 MΩ cm) obtained from a Milli-Q water purification system (Millipore Corp., Bedford, MA, USA). 2.1 Fabrication of FPAN cloth Commercial nylon cloth was cut into small pieces (3.0×3.0 cm2) after being washed and dried in oven. The cloth was dip-coated with purchased AgNWs dispersion (5 mg/ml) for several times. The mass loading of AgNWs in the cloth was controlled by dip-coating times and was about 0.9 mg/cm2 in this work. After dried in vacuum oven for 30 min at 60 °C, the AgNWs coated nylon cloth (AN cloth) was dip-coated with PDMS. The PDMS elastomer and cross-linker (Sylgard 184, Tow Corning) were thoroughly mixed in a 10: 1 ratio (w/w). AN cloth were placed into PDMS solution and degassed for 30 min. After that, AN cloth coated by a layer of PDMS (ca. 240 µm in thickness) were cured in 80 °C oven for 2 h. The prepared film (PAN cloth) were then dip-coated with fluoroalkylsilanes (FAS, F8261, Degussa) mixed solution of isopropyl alcohol and water with a concentrate of 1.26 wt% and dried in oven at 60 °C for 1 h. Without coating AgNWs, FAS-PDMS-nylon (FPN) cloth was fabricated by the same method as that of FPAN cloth. 2.2 Characterization and measurements The morphology of the samples was characterized by field emission scanning electron microscopy (FE-SEM, S-4800, Hitachi, Japan). To measure the out-put performance of energy harvesting, we used FPAN cloth to work as the bottom layer of a TENG. The top side was made


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of kapton double-side adhesive tape with commercial PET cloth and Al foil on both sides. A Keithley 2657A was used to detect the output voltage, short-circuit current of the TENG and the voltage across the capacitor during the charging process. The voltage was measured under an external load of 100 MΩ. The contact angle of each droplet was determined automatically using the Laplace-Young fitting algorithm. A mechanical motor (home-made device) was used to make two surfaces of the TENG contact and separate periodically to result in a triboelectric potential and an electrical output in the external circuit. A Keithley 2400 was used to apply direct voltage for FPAN cloth. The temperature changes in the experiment were measured by infrared thermometer (Optris LS, German) and thermal images were taken by an infrared camera (FLIR A300-Serious, Sweden).

3. Results and discussion 3.1 The structure and composition of energy management device. The flexible FPAN cloth with multilayer-coating structure was fabricated by dip-coating AgNWs, PDMS and FAS in sequence (Figure 1a), forming a total thickness of 580 µm (Figure 1c). As the innermost layer, commercial nylon textile has good hydrophilicity and wettability, ensuring the good adhesion, large mass loading and uniform distribution of AgNWs on it. AgNWs have a high aspect ratio, which is beneficial to the formation of a highly connected network with good bending resistance.33-35 These highly connected networks are also the key factor of hindering the loss of human body heat. PDMS was used as triboelectric material and also to protect AgNWs from being oxidized and peeled off under the high temperatures and different deformations, respectively. As we can see in Figure 1d, AgNWs were well imbedded into PDMS, forming a uniform AgNWs/PDMS layer. The space between AgNWs/PDMS layer


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and nylon fiber was caused by the shear force when prepared the sample for SEM test. FAS is a kind of common water-repellent coating, which has very low surface energy. By hydrolysis, FAS (C8F13H4Si(OR)3,) reacts with water to form silicon hydroxide as a reactive group at the end of the molecule. The molecule is bound to the substrate (here is PDMS) via the reactive silane end with virtually no interaction between the neighboring fluoroalkyl tails, leading to a maximum stable thickness of one monolayer.36 Also, the strong silicon hydride bonds ensure the mechanical durability of the TENGs. The multilayer compound of these materials makes it possible for FPAN cloth to work as multifunctional device without weakening its high flexibility. However, the final textile sacrificed its breathable property, which is also important for wearable applications. To solve the problem, FPAN cloth was inserted in large area cloth like many functional “islands”, the rest part of the cloth were still original nylon cloth for a compromise of both multifunction and breathability. (Figure S1)


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Figure 1. (a)The fabrication process of FPAN cloth, (b) the cross-sectional schematic diagram of the FPAN cloth, (c) SEM image of the cross section and (d) its high magnification view of the FPAN cloth. 3.2 Working as TENG for energy harvesting. For transforming mechanical energy to electricity, FPAN cloth works as bottom side of a TENG, which is separated into two parts (FAS/PDMS and AN cloth) in the schematic illustration for clearly elaborating the work mechanism of TENG (Figure 2a). The cyclic compressive force and releasing of the devices in this work is applied by mechanical force stimulator (Figure 2b). At the original state, there is no charge transfer. When two materials (FAS/PDMS and PET cloth in this case) are compressed to contact, equal and opposite charges are produced on each surface due to triboelectric effect.37-39 According to triboelectric series, electrons are injected into the FAS/PDMS from the PET cloth, which results in positively charged PET cloth and negatively


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charged FAS/PDMS. At this stage, TENG remains in electrostatic equilibrium state because of a negligible dipole moment. When the TENG is released, to keep the electrostatic neutral state of each side, electrons flow from AN cloth to Al foil, then the electric signal is observed. As two surfaces are forced to contact again, the former electrostatic equilibrium is broken, and electrons flow back from the top Al electrode to AN cloth through the external circuit, then the opposite electric signal is detected. Therefore, under continuous compressing and releasing the device can generate sustained alternating current through the external circuit (Figure 2c).

Figure 2. (a) Schematic illustration of working principle of the TENG with electron and current flow diagrams. (b) The digital photo of home-made mechanical motor, which is used for cyclic application of compress force and releasing. (c) A complete cycle of electric signal. Here, out-put performance of PAN cloth as the bottom side of TENG was measured at first. The maximum voltage and short-circuit current of PAN cloth based TENG can reach 53.2 V and 1.1 µA (Figure 3c, d), respectively. To improve the out-put performance, a facile dip-coating method was used to graft FAS onto the surface of PDMS. After that, a much higher voltage of


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approximately 575 V and a short-circuit current of 12.1 µA were observed from FPAN cloth based TENG under the same compressive force (Figure 3e, f). The smooth surfaces of both cloths (Figure 3a, b and High-resolution images in Figure S2) mean that the FPAN cloth remains the same surface morphology of PAN cloth. Thus, the possible reasons of the remarkable enhancement are demonstrated as follows: 1. According to triboelectric series, the halogenate polymers develop the most negative charge.40 FAS is more negative than PDMS in the triboelectric series, causing larger triboelectric difference between two sides of TENG and then higher output performance.27 2. The FAS grafted on PDMS makes the surface more hydrophobic, which can be proved by the difference of the contact angles of PAN cloth and FPAN cloth (112 ° and 131 °, respectively) (Figure 3e, f). Surface charge will decrease along with increase of ambient relative humidity.41 This is because the formation of a water layer on the surface of triboelectric materials increases the surface conductivity, and thus, discharges the surfaces.42 3. The lower surface energy of FAS makes the separation process of FPAN cloth based TENG easier and more effective, which also contributes to higher out-put powers. The strong chemical bond between FAS and PDMS ensures the durability of FPAN cloth, which was also detected by comparison of the output voltage of FPAN cloth based TENG before and after 12000 contact-separation cycles (Figure S3a). No significant differences were observed, proving the good mechanical durability of FPAN cloth based TENG.

The out-put performance is in a high level compared to other textile-based TENGs,6, 25, 26, 43-45 revealing its great potential to power small-scale electronic devices with low power consumption. Furthermore, without sacrificing the flexibility and stability of TENG, the fabrication process is much more low-cost and simpler than the universally existing methods


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used to improve the out-put performance of TENGs, such as hydrothermal method,24, 46 inductive coupling plasma reactive ion etching,47, 48 electrospun,49 etc.

Figure 3. FE-SEM images of the surfaces of (a) PAN cloth and (b) FPAN cloth (insets are the contact angles between water and samples). The out-put performance of PAN cloth based TENG: (c) voltages and (d) short-circuit currents. The out-put performance of FPAN cloth based TENG: (e) voltages and (f) short-circuit currents. To further explore the out-put performance of FPAN cloth based TENG for powering external loads, voltage and current as function of different load resistance were measured. As shown in figure 4a, the voltage increases with the increase of resistance ranging from 0.1 MΩ to 1000 MΩ, while the current demonstrates a diverse trend. As a result, the corresponding power density


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of the device reaches a maximum value of 2.77 W/m2 at external resistance of about 100 MΩ. In this work, two commercial capacitors with value of 4.7 µF and 22 µF were charged by TENG to store the harvested energy for continuously and steadily powering small electronics. Also, a rectification circuit was used to turn the alternate current signal into a direct current signal (Figure 4d) and the out-put voltage signal after rectification is shown in Figure S3b. The charging curves in figure 4c confirm that 4.7 µF and 22 µF capacitors are charged respectively to 12 V and 4 V within 500 s under the same compressive force in this work. The out-put signals in this work were all obtained with a contact-separation frequency of 1.8 Hz. Furthermore, the device was successfully used to instantaneously light 247 LEDs connected in series (inset of Figure 4b) without any energy storage-system to prove its potential application as power source. Furthermore, PET cloth, top layer of the TENG, can be replaced by different kinds of cloth when applied in wearable area. For potential application, the device can also be used as a singleelectrode based cell without the top side,50 thus largely expanding its application range in wearable area.


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Figure 4. (a) Out-put voltages and currents of FPAN cloth based TENG with different resistors as external loads. (b) The dependence of instantaneous power on external load resistance (inset is digital pictures of 247 brightened LEDs connected in series, forming two straight lines and letters “DHU SKL FPM”). (c) Charging curves of 4.7 µF and 22 µF commercial capacitors by FPAN cloth based TENG. (d) Rectifier circuit diagram of the prototype energy-harvesting to charge capacitors and lit LEDs. 3.3 Working as heat insulation for thermal management. Besides harvesting mechanical energy, FPAN cloth can keep people warm by hindering heat loss from human body and raise skin temperature when voltage was applied. In this way, a large amount of energy which used for indoor heating can be saved. As we know, the continuous absorption and emission of IR from human body into the ambient air is a major portion of the heat loss.10 Because of its high emissivity (0.75-0.9),29 normal cloth provides too little radiative insulation to hinder heat loss from human body. AgNWs were introduced into the cloth to


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function as the heat insulation layer more than conductive electrode. Firstly, the spaces between nanowires coating on nylon cloth were controlled to be less than 300 nm (Figure 5a), which is much smaller than length of IR radiated from human body (9 µm). Therefore, a large part of IR will be reflected to human body. Also, the FE-SEM images of normal nylon cloth and AgNWscoated nylon cloth are shown in Figure S4. Secondly, bulk Ag has quite low emissivity of about 0.02. According to the Stefan-Boltzmann law which describes thermal emission of objects, the emissivity (ε) is positively related to thermal emission. The equation of the Stefan--Boltzmann law is demonstrated as follows: j = εσT4

(1)

Where j is the total energy flux, ε is the material emissivity, σ is Stefan-Boltzmann constant, and T is the temperature. In our work, low emissivity of AgNWs makes the film radiate much less heat than normal nylon cloth (ε is about 0.8) at the same temperature. To measure the radiation insulation performance of FPAN cloth, three different samples (nylon cloth, FPN cloth, FPAN cloth) were tested on an open-air hotplate (Figure 5c). Firstly, the temperature of the hot plate was set to 37 °C to simulate human core temperature. Temperatures of the samples were measured by an Infrared Thermometer when they were placed on the hot plate (Figure 5c). Thus, the drops between temperatures of measured samples and hot plate are in direct proportion to thermal insulation. The temperature drops of nylon cloth, FPN cloth and FPAN cloth are calculated as 1.6 °C, 2 °C and 4.6 °C, respectively. The better performance of FPAN cloth compared to FPN cloth proves the importance of AgNWs network in heat insulation as we discussed above. Overall, the FPAN cloth provides 8 % more thermal insulation than normal cloth at 37 °C. Furthermore, the temperature of the hot plate was respectively set to 50 °C (Figure 5d) and 80 °C (Figure S5a), obtaining the same trend of temperature drop of the three


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samples. It’s worth mentioning that the grafted FAS has no adverse effect to the heat insulation of the films when we compare PAN cloth and FPAN cloth using the same measurement (Figure S5 b-d). The results show the good heat insulation of FPAN cloth at different temperatures, expanding its application area to flexible insulation materials more than wearable energy-saving device. The thermal image of nylon cloth and FPAN cloth both put in a palm (Figure 5b) vividly shows the better heat insulation of FPAN cloth. Thermal image was taken after all samples were in thermal equilibrium with the palm. In the thermal image, the colors of nylon cloth and FPAN cloth are obviously different, nylon cloth shows green while FPAN cloth appears blue. Although two samples have the same temperature as palm, the thermal insulation of FPAN cloth makes itself appear “colder” in thermal image. Calculated by the analysis software, the average temperature of palm, nylon cloth and FPAN cloth are 35.6 °C, 34.9 °C and 33.4 °C, respectively. This confirms the method of using AgNWs network on textiles to be applicable and effective.


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Figure 5. (a) FE-SEM images of AgNWs on the surface of nylon cloth. (b) Infrared camera thermal image of commercial nylon cloth (up) and FPAN cloth (down) in the palm (inset is corresponding digital photographs of samples (ca. 3.0×3.0 cm2)). (c) Temperatures of different samples kept on an open-air hotplate at 37 °C, insets are the corresponding digital photographs of three samples) and (d) temperatures of different samples kept on an open-air hotplate at 50 °C. 3.4 Working as a highly flexible heater for thermal management. More than passively insulating heat loss, the FPAN cloth also functions as a wearable heater obtaining desirable temperatures, fast thermal response and uniform heating. Figure 6a shows the cloth can be raised to different temperatures with different voltages and efficiently raised to 40 °C within 4min when only 1.5 V voltage was applied. Uniform heating is also observed in the thermal images, which is regarded as one of the most important criteria in electrical heaters.51 In Figure 6b, the FPAN cloth is easily attached to the bent surface of the back of hand with good conformal coverage. What’s more, thermal images (Figure 6c-e) were taken when FPAN cloth


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were folded, twisted and even crushed, which are commonly involved in human motion. The results prove that the cloth exhibits fine performance with high stability at mechanical disturbances. Besides the low voltage, there is no worry of safety threat to human because the conductive part was encapsulated by insulated PDMS. In conclusion, compared to the most commonly used portable heat packs and wraps, the FPAN cloth has many advantages, such as light weight, high flexibility, controllable temperature and safety.

Figure 6. (a) Temperature changes versus time after applying different voltages to a 3.0 cm × 3.0 cm sample of FPAN cloth. (b) Infrared camera thermal image of FPAN cloth on the back of hand when applied voltage (1.5 V) (inset is the corresponding digital photograph). Thermal images (up) and corresponding digital photos (down) of 4.0 × 6.0 cm2 samples of FPAN cloth when they were (c) folded, (d) twisted and (e)crushed. 4. Conclusions


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In summary, this work demonstrates a textile-based personal energy management device with multilayer-coating structure (nylon cloth, AgNWs, PDMS and FAS). For energy harvesting, FAS was grafted onto the surface of PDMS for the enhancement of surface charge of the TENG, thus remarkably improving the out-put performance. The device reached a maximum instantaneous power density of 2.8 W/m2 and successfully lighted 247 LEDs connected in series without any energy storage-system. For energy saving, the device had good heat insulation property and can be raised to 40 °C from 25 °C within 4min when applied only 1.5 V voltage. The flexibility and stability of the cloth make the personal EM device perfect candidate in wearable area. Therefore, it’s optimistic that our work will have a promising application to power wearable electronics and offer a novel part of the solution for wearable personal energy management.

ASSOCIATED CONTENT Supporting Information Schematic diagram of FPAN cloth inserted in nylon fabric as functional “islands” (Figure S1). High-resolution FE-SEM images of the surfaces of PAN cloth and FPAN cloth (Figure S2). The out-put open circuit voltages of FPAN cloth based TENG after 12000 contact-separation cycles and after rectification (Figure S3). FE-SEM images of nylon cloth and AgNWs-coated nylon cloth (Figure S4). Temperatures of different samples put on open-air hot plate kept on different temperatures (Figure S5). This material is available free of charge via the Internet at http://pubs.acs.org. AUTHOR INFORMATION Corresponding Author * Tel: +86-21-67792881; fax: +86-21-67792855. E-mail address: [email protected] (Q. H. Zhang), [email protected] (H. Z. Wang).


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Notes The authors declare no completing financial interest. ACKNOWLEDGMENT We gratefully acknowledge Key Projects in the National Science & Technology Pillar Program (2013BAE01B03),

Science

and

Technology

Commission

of

Shanghai

Municipality

(13JC1400200), Shanghai Natural Science Foundation (15ZR1401200), Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning, Innovative Research Team in University (IRT1221), Program of Introducing Talents of Discipline to Universities (No.111-2-04) and Fundamental Research Funds for the Central Universities (2232014A3-06) and Doctor Innovation Program of Donghua University (CUSFDH-D-2015028).

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Grating-Structured

Freestanding

Triboelectric-Layer

Nanogenerator

for

Harvesting

Mechanical Energy at 85% Total Conversion Efficiency. Adv. Mater. 2014, 26, 6599-6607. (48)Yang, J.; Y.; Chen, J.; Su, Y. J; Jing, Q. S.; Li, Z. L.; Yi, F.; Wen, X. N.; Wang, Z. N.; Wang, Z. L. Eardrum-Inspired Active Sensors for Self-Powered Cardiovascular System Characterization and Throat-Attached Anti-Interference Voice Recognition. Adv. Mater. 2015, 27, 1316-1326. (49)Zheng, Y.; Cheng, L.; Yuan, M.; Wang, Z.; Zhang, L.; Qin, Y.; Jing, T. An Electrospun Nanowire-Based Triboelectric Nanogenerator and Its Application in A Fully Self-Powered UV Detector. Nanoscale 2014, 6, 7842-7846. (50)Yang, Y.; Zhou, Y. S.; Zhang, H.; Liu, Y.; Lee, S.; Wang, Z. L. A Single-Electrode Based Triboelectric Nanogenerator as Self-Powered Tracking System. Adv. Mater. 2013, 25, 65946601. (51)Hong, S.; Lee, H.; Lee, J.; Kwon, J.; Han, S.; Suh, Y. D.; Cho, H.; Shin, J.; Yeo, J.; Ko, S. H. Highly Stretchable and Transparent Metal Nanowire Heater for Wearable Electronics Applications. Adv. Mater. 2015, 27, 4744-4751.


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The table of contents


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Fluoroalkylsilane-Modified Textile-Based Personal Energy

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