Highly Stretchable Multifunctional Wearable Devices Based on Conductive Cotton and Wool Fabrics

Transcription

1 Supporting Information for Highly Stretchable Multifunctional Wearable Devices Based on Conductive Cotton and Wool Fabrics Hamid Souri 1* and Debes Bhattacharyya 1 1 Centre for Advanced Composite Materials, Department of Mechanical Engineering, The University of Auckland, Auckland, New Zealand, Corresponding author (H. S.) hsou970@aucklanduni.ac.nz S-1

2 This file includes: Figures S1-S11 Tables S1-S2 Figure S1. SEM images of the neat materials. a) surface of wool fabric and b) its single fiber, c) surface of cotton fabric, and d) its fibers. S-2

3 Figure S2. Cross sectional SEM images of our multifunctional devices. a) our CC strain sensor, b) our CW strain sensor, c) our CC heater, and d) our CW heater. Holm s contact theory: 2 1 Where Rc, n, ρ, H, and P denotes the contact resistance between neighbouring paths in a knitted fabric, the number of contact points, electrical resistivity of the coated yarn, the hardness of the material, and the pressure made by contacts, respectively. Among these parameters, the resistivity and the hardness of the materials can be considered as a constant value for a specific material. Thus, decrease in Rc will occur when more contact points are formed as a result of increased pressure by the applied tensile strains (Figure S3). 14 S-3

4 Figure S3. Schematic illustration indicating the structure of our conductive knitted fabrics and the contact points. S-4

5 Figure S4. a) Relative changes of resistance versus strain under cyclic stretching releasing at displacement rate of 5 mm.s -1 for CC strain sensors and b) for CW strain sensors. c) the relative changes of resistance versus strain under cyclic stretching releasing at displacement rate of 10 mm.s -1 for CC strain sensors and d) for CW strain sensors. S-5

6 Figure S5. Relative resistance variations under cyclic stretching releasing at displacement rates of 3, 5, and 10 mm.s -1 for our a) CC strain sensors at 100%, b) CW strain sensors at 100%, c) CC strain sensors at 150%, and d) CW strain sensors at 150%. S-6

7 Table S1. Comparison of main performance of our strain sensors and recently reported strain sensors with large strain range sensing. Strain sensors Our work (graphene nanoplatelets and carbon black coated cotton or wool/ecoflex) Carbonized melamine Reported strain range (%) CC: 150% CW: 150% Gauge factors CC: CW: Durability 1000 cycles at 75% for CC and CW based strain sensors 10,000 cycles at 20% sponges/pdms 1 100% Carbon black/pdms 2 10% Not shown Carbon black/ecoflex 3 400% cycles at 100% Carbon nanotube 10,000 cycles at film/pdms 4 280% % Carbon black/elastomer 5 80% cycles at 80% AgNWs/PEDOT:PSS/PU 6 100% cycles at 30% AuNWs/latex rubber 7 350% cycles at 50% CNTs/Ecoflex 8 500% cycles at 300% S-7

8 Figure S6. Performance of our CC strain sensors under 1000 cyclic stretching releasing loading at 15 mm.s -1. S-8

9 Figure S7. Photographs exhibiting the bending-holding of a volunteer s finger with our strain sensor attached on the finger a) straight position, b) angle of bending is greater than 45. Photographs indicating the bending-holding of a volunteer s c) knee and d) wrist joint movements. S-9

10 Figure S8. Plots showing the responses of our a) CC, b) CW strain sensors to a unique played track, when installed on a speaker (as shown in the inset), and c) plots showing the GFs of CC and CW strain sensors at the displacement rate of 10 mm.s -1 up to ε=0.5%. S-10

11 Thermogravimetric Analysis (TGA): The TGA graphs of the pristine and conductive fabrics under N 2 atmosphere are shown in Figure S8. The results indicate an initial weight loss for all of the samples due to the presence of stored water. 9 Major weight loss can be seen in both cotton and conductive cotton fabrics at about 350 C; on the other hand, the wool and conductive wool fabrics showed their major loss in weight at about 250 C. Overall, cotton fabrics exhibited more than 98% of weight loss up to 800 C whereas the coating could decrease the weight loss to about 94%. The weight loss during the pyrolysis up to 800 C was almost 80 and 71% for wool and conductive wool fabrics. The higher amount of residuals for wool and conductive wool after the TGA test is due to the formation of char. Moreover, one could notice that lower weight loss was obtained for the coated cotton and wool fabrics compared to the neat fabrics due to the presence of carbon particles. The results indicate the thermal stability of our fabrics in the working temperature range of our wearable heaters. Figure S9. TGA thermograms of various fabrics, indicating their thermal behavior up to 800 C. S-11

12 Figure S10. IR images demonstrating the temperature distribution on the surface of our a) CC and b) CW heaters, when attached on a volunteer s hand. Table S2. Comparison of main performance of our heaters and previously reported heaters. Heaters/Active materials Our work (graphene nanoplatelets and carbon black coated Cotton or Wool /Ecoflex) Reported Applied Voltage (V) CC:50 CW:20 Maximum Temperature (ºC) CC:95.3 CW:103 Temperature variation by deformation CC: From 78.8 ºC to 90.1 ºC under 50% of tensile strain CW: From 91.6 ºC to ºC under 20% of tensile strain Graphene Not shown 5 ºC dropped by Graphene-AuCl % applied tensile strain CNT/Cotton Not shown MWCNTs Not shown S-12

13 Figure S11. Steady-state maximum temperatures (T max ) of CC and CW heaters as a function of the input electric power (P in ). Figure S12. Our strain sensor gripped with the motorized moving stage. a) before stretching, b) while stretching. S-13

14 References: (1) Fang, X.; Tan, J.; Gao, Y.; Lu, Y.; Xuan, F. High-Performance Wearable Strain Sensors Based on Fragmented Carbonized Melamine Sponges for Human Motion Detection. Nanoscale 2017, 9, (2) Kong, J. H.; Jang, N. S.; Kim, S. H.; Kim, J. M. Simple and Rapid Micropatterning of Conductive Carbon Composites and Its Application to Elastic Strain Sensors. Carbon N. Y. 2014, 77, (3) Muth, J. T.; Vogt, D. M.; Truby, R. L.; Mengüç, Y.; Kolesky, D. B.; Wood, R. J.; Lewis, J. A. Embedded 3D Printing of Strain Sensors within Highly Stretchable Elastomers. Adv. Mater. 2014, 26, (4) Yamada, T.; Hayamizu, Y.; Yamamoto, Y.; Yomogida, Y.; Izadi-Najafabadi, A.; Futaba, D. N.; Hata, K. A Stretchable Carbon Nanotube Strain Sensor for Human- Motion Detection. Nat. Nanotechnol. 2011, 6, (5) Mattmann, C.; Clemens, F.; Tröster, G. Sensor for Measuring Strain in Textile. Sensors 2008, 8, (6) Hwang, B. U.; Lee, J. H.; Trung, T. Q.; Roh, E.; Kim, D. Il; Kim, S. W.; Lee, N. E. Transparent Stretchable Self-Powered Patchable Sensor Platform with Ultrasensitive Recognition of Human Activities. ACS Nano 2015, 9, (7) Gong, S.; Lai, D. T. H.; Su, B.; Si, K. J.; Ma, Z.; Yap, L. W.; Guo, P.; Cheng, W. Highly Stretchy Black Gold E-Skin Nanopatches as Highly Sensitive Wearable Biomedical Sensors. Adv. Electron. Mater. 2015, 1, 1 7. (8) Amjadi, M.; Yoon, Y. J.; Park, I. Ultra-Stretchable and Skin-Mountable Strain Sensors Using Carbon Nanotubes-Ecoflex Nanocomposites. Nanotechnology 2015, 26, (9) Jung, I.; Dikin, D.; Park, S.; Cai, W.; Mielke, S. L.; Ruoff, R. S. Effect of Water Vapor on Electrical Properties of Individual Reduced Graphene Oxide Sheets. J. Phys. Chem. C 2008, 112, (10) Sui, D.; Huang, Y.; Huang, L.; Liang, J.; Ma, Y.; Chen, Y. Flexible and Transparent Electrothermal Film Heaters Based on Graphene Materials. Small 2011, 7, (11) Kang, J.; Kim, H.; Kim, K. S.; Lee, S. K.; Bae, S.; Ahn, J. H.; Kim, Y. J.; Choi, J. B.; Hong, B. H. High-Performance Graphene-Based Transparent Flexible Heaters. Nano Lett. 2011, 11, (12) Zhang, M.; Wang, C.; Liang, X.; Yin, Z.; Xia, K.; Wang, H.; Jian, M.; Zhang, Y. Weft-Knitted Fabric for a Highly Stretchable and Low-Voltage Wearable Heater. Adv. Electron. Mater. 2017, 3, 1 8. (13) Jung, D.; Kim, D.; Lee, K. H.; Overzet, L. J.; Lee, G. S. Transparent Film Heaters Using Multi-Walled Carbon Nanotube Sheets. Sensors Actuators, A Phys. 2013, 199, (14) HOLM, R. ELECTRIC CONTACTS: THEORY AND APPLICATION, 4th ed; Springer Science & Business Media, Germany, S-14

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