Supporting Information

Supertough and ultrasensitive flexible electronic skin based on

nanocellulose/sulfonated carbon nanotube hydrogel films

Haiyu Xu,a,b Yuanyuan Xie, b Enwen Zhu, b Yan Liu, b Zhuqun Shi,* a,b Chuanxi Xiong*b

and Quanling Yang*b

a School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of

Technology, Luoshi Road 122, Wuhan 430070, China

b School of Materials Science and Engineering, Wuhan University of Technology,

Luoshi Road 122, Wuhan 430070, China

Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A.This journal is © The Royal Society of Chemistry 2020

The distribution of conductive fillers in the hydrogel film has a great influence on

the E-skin sensing performance. The sulfonic acid groups were introduced into the

surface of the carbon nanotube by sulfonation modification of to improve the

dispersibility of the carbon nanotube in water. Therefore, in order to determine the

dispersion of sulfonated carbon nanotubes (SCNT) in the hydrogel films, we used

surface scanning with SEM-EDS to analyze the distribution of "S" element on the

sulfonic acid groups. As shown in Fig. S1a, we found that the S element was uniformly

distributed in the three-dimensional network of the hydrogel film without aggregation

and accumulation.

a b

100 nm

Fig. S1. (a) The distribution of S element in three-dimensional network of TOCN/SCNT hydrogel film. (b) The SEM image of SCNT.

Fig. S2. (a) Photograph of unmodified CNTs (left) and sulfonated CNTs (right) in water after 30 min of sonication and 24 h of rest. Comparison of light paths between the unmodified CNTs (b) and sulfonated CNTs (c) in water dispersed systems.

Fig. S3. (a) Nitrogen isotherm adsorption-desorption curves and (b) pore distribution curves of TOCN/SCNT and TOCN/CNT hydrogel films.

Fig. S4. FTIR spectra of SCNT, CNT, TOCN/SCNT, TOCN/CNT, and TOCN.

10 20 30 40 50 60 702θ/deg

SCNT

CNT

TOCN/SCNT

TOCN/CNT

TOCN

Fig. S5. XRD spectra of SCNT, CNT, TOCN/SCNT, TOCN/CNT and TOCN hydrogel films.

Fig. S6. (a) The conductivity of hydrogel films with CNT and SCNT. (b) Lighting the LED with TOCN/SCNT as the wire.

Fig. S7. Photograph of surface of gauze with a sparse crisscross structure.

Fig. S8. The sensitivity of E-skin with different mass ratios of TOCN/SCNT

Fig. S9. The response time and recovery time of the E-skin with high frequency and irregular pressures (0-5 KPa). Insets a1 and a2 show the response time and recovery time of the E-skin at different moments and pressures.

Table S1 Summary of the performance of flexible pressure sensors reported in the literature.

Key materials Sensitivity Limit of

detection

Response

time

Cycling

numbers

Fracture

energy

(MJ/m3)

Refs.

AgNWs/tissue paper 1.5 kPa-1 30 Pa 90 ms - - 1

CNT/fabric 1.4 kPa-1 0.43 N >5000 9 2

Molecule-rGO /PET 0.82 kPa-1 7 Pa 24 ms 2000 - 3

Microdome-patterned

rGO/PVDF

47.7 kPa-1 1.3 Pa 20 ms 5000 - 4

H2SO4/PAA/PVA

hydrogel

121.1 nF kPa-

1

- - 100 18.7 5

CB/TPU 3D printing 5.54 kPa-1 10 Pa 20 ms 10000 - 6

Graphene/PDMS

microstructured

8.5 kPa-1 1 Pa 40 ms 10000 - 7

LN/MWCNTs/PP 28.8 nA kPa-1 8 Pa 40 >3000 2.6 8

CB/PU sponges 0.068 kPa-1 17 Pa <20 ms 50000 - 9

rGO-Ag NW@cotton

fiber

4.23 kPa-1 - 200 ms - - 10

Liquid metals-

hydrogels

0.25 kPa-1 - 180 ms 1000 12 11

PVA/PAM/KCl

hydrogel

- - - - 2.7 12

Our work 4.4 kPa-1 0.5 Pa ≤10 ms 11000 240.3

References1 L. Gao, C. Zhu, L. Li, C. Zhang and W. Huang, ACS Appl. Mater. Interfaces, 2019, 11, 25034-

25042.2 Y. Song, W. Huang, C. Mu, X. Chen, Q. Zhang, A. Ran, Z. Peng, R. Sun and W. Xie, Adv.

Mater. Technol., 2019, 4, 1800680.3 C. B. Huang, S. Witomska, A. Aliprandi, M. A. Stoeckel, M. Bonini, A. Ciesielski and P.

Samorì, Adv. mater., 2019, 31, 1804600.4 Y. Lee, J. Park, S. Cho, Y.-E. Shin, H. Lee, J. Kim, J. Myoung, S. Cho, S. Kang and C. Baig,

ACS nano, 2018, 12, 4045-4054.5 M. X. Wang, Y. M. Chen, Y. Gao, C. Hu, J. Hu, L. Tan and Z. Yang, ACS Appl. Mater.

Interfaces, 2018, 10, 26610-26617.6 Z. Wang, X. Guan, H. Huang, H. Wang, W. Lin and Z. Peng, Adv. Funct. Mater., 2019, 29,

1807569.7 G. Y. Bae, S. W. Pak, D. Kim, G. Lee, D. H. Kim, Y. Chung and K. Cho, Adva. Mater., 2016,

28, 5300-5306.8 M. Xu, H. Kang, L. Guan, H. Li and M. Zhang, ACS Appl. Mater. Interfaces, 2017, 9, 34687-

34695.9 X. Wu, Y. Han, X. Zhang, Z. Zhou and C. Lu, Adv. Funct. Mater., 2016, 26, 6246-6256.10 M. Cao, M. Wang, L. Li, H. Qiu, M. A. Padhiar and Z. Yang, Nano energy, 2018, 50, 528-535.11 H. Peng, Y. Xin, J. Xu, H. Liu and J. Zhang, Mater. Horiz., 2019, 6, 618-625.12 M. Liao, P. Wan, J. Wen, M. Gong, X. Wu, Y. Wang, R. Shi and L. Zhang, Adv. Funct. Mater.,

2017, 27, 1703852.