High-Porosity Foam-Based Iontronic Pressure Sensor with Superhigh Sensitivity of 9280 kPa−1
Corresponding Author: Chuan Fei Guo
Nano-Micro Letters,
Vol. 14 (2022), Article Number: 21
Abstract
Flexible pressure sensors with high sensitivity are desired in the fields of electronic skins, human–machine interfaces, and health monitoring. Employing ionic soft materials with microstructured architectures in the functional layer is an effective way that can enhance the amplitude of capacitance signal due to generated electron double layer and thus improve the sensitivity of capacitive-type pressure sensors. However, the requirement of specific apparatus and the complex fabrication process to build such microstructures lead to high cost and low productivity. Here, we report a simple strategy that uses open-cell polyurethane foams with high porosity as a continuous three-dimensional network skeleton to load with ionic liquid in a one-step soak process, serving as the ionic layer in iontronic pressure sensors. The high porosity (95.4%) of PU-IL composite foam shows a pretty low Young’s modulus of 3.4 kPa and good compressibility. A superhigh maximum sensitivity of 9,280 kPa−1 in the pressure regime and a high pressure resolution of 0.125% are observed in this foam-based pressure sensor. The device also exhibits remarkable mechanical stability over 5,000 compression-release or bending-release cycles. Such high porosity of composite structure provides a simple, cost-effective and scalable way to fabricate super sensitive pressure sensor, which has prominent capability in applications of water wave detection, underwater vibration sensing, and mechanical fault monitoring.
Highlights:
1 High porosity and low modulus of the active layer are found to contribute to high sensitivity in a capacitive pressure sensor.
2 Pressure sensor achieves a superhigh sensitivity of 9280 kPa-1 by using polyurethane-ionic liquid foam with a high porosity (95.4%) and a low modulus (3.4 kPa).
Keywords
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References
S. Sundaram, P. Kellnhofer, Y. Li, J.Y. Zhu, A. Torralba et al., Learning the signatures of the human grasp using a scalable tactile glove. Nature 569, 698–702 (2019). https://doi.org/10.1038/s41586-019-1234-z
G. Schwartz, C.K. Tee, J. Mei, A.L. Appleton, D.H. Kim et al., Flexible polymer transistors with high pressure sensitivity for application in electronic skin and health monitoring. Nat. Commun. 4, 1859 (2013). https://doi.org/10.1038/ncomms2832
C.C. Kim, H.H. Lee, K.H. Oh, J.Y. Sun, Highly stretchable, transparent ionic touch panel. Science 353(6300), 682–687 (2016). https://doi.org/10.1126/science.aaf8810
J.Y. Sun, C. Keplinger, G.M. Whitesides, Z. Suo, Ionic skin. Adv. Mater. 26(45), 7608–7614 (2015). https://doi.org/10.1002/adma.201403441
C.F. Guo, L. Ding, Integration of soft electronics and biotissues. Innovation 2(1), 100074 (2020). https://doi.org/10.1016/j.xinn.2020.100074
Q. Liu, X.X. Wang, W.Z. Song, H.J. Qiu, J. Zhang et al., Wireless single-electrode self-powered piezoelectric sensor for monitoring. ACS Appl. Mater. Interfaces 12(7), 8288–8295 (2020). https://doi.org/10.1021/acsami.9b21392
Z. Yu, W.B. Ying, D. Pravarthana, Y. Li, Y. Liu et al., Stretchable tactile sensor with high sensitivity and dynamic stability based on vertically aligned urchin-shaped nanoparticles. Mater. Today Phys. 14, 100219 (2020). https://doi.org/10.1016/j.mtphys.2020.100219
J. Lee, H. Kwon, J. Seo, S. Shin, J.H. Koo et al., Conductive fiber-based ultrasensitive textile pressure sensor for wearable electronics. Adv. Mater. 27(15), 2433–2439 (2015). https://doi.org/10.1002/adma.201500009
W. Xu, H. Zheng, Y. Liu, X. Zhou, C. Zhang et al., A droplet-based electricity generator with high instantaneous power density. Nature 578, 392–396 (2020). https://doi.org/10.1038/s41586-020-1985-6
Y. Wan, Z. Qiu, Y. Hong, Y. Wang, J. Zhang et al., A highly sensitive flexible capacitive tactile sensor with sparse and high-aspect-ratio microstructures. Adv. Electron. Mater. 4(4), 1700586 (2018). https://doi.org/10.1002/aelm.201700586
S.C.B. Mannsfeld, B.C.K. Tee, R.M. Stoltenberg, C.V.H.H. Chen, S. Barman et al., Highly sensitive flexible pressure sensors with microstructured rubber dielectric layers. Nat. Mater. 9, 859–864 (2010). https://doi.org/10.1038/NMAT2834
B. Nie, S. Xing, J.D. Brandt, T. Pan, Droplet-based interfacial capacitive sensing. Lab Chip 12(6), 1110–1118 (2012). https://doi.org/10.1039/c2lc21168h
B. Nie, R. Li, J. Cao, J.D. Brandt, T. Pan, Flexible transparent iontronic film for interfacial capacitive pressure sensing. Adv. Mater. 27(39), 6055–6062 (2015). https://doi.org/10.1002/adma.201502556
J. Yang, Q. Liu, Z. Deng, M. Gong, F. Lei et al., Ionic liquid-activated wearable electronics. Mater. Today Phys. 8, 78–85 (2019). https://doi.org/10.1016/j.mtphys.2019.02.002
R. Li, Y. Si, Z. Zhu, Y. Guo, Y. Zhang et al., Supercapacitive iontronic nanofabric sensing. Adv. Mater. 29(36), 1700253 (2017). https://doi.org/10.1002/adma.201700253
S. Li, N. Pan, Z. Zhu, R. Li, B. Li et al., All-in-one iontronic sensing paper. Adv. Funct. Mater. 29(11), 1807343 (2019). https://doi.org/10.1002/adfm.201807343
A. Chhetry, J. Kim, H. Yoon, J.Y. Park, An ultrasensitive interfacial capacitive pressure sensor based on a randomly distributed microstructured iontronic film for wearable applications. ACS Appl. Mater. Interfaces 11(3), 3438–3449 (2019). https://doi.org/10.1021/acsami.8b17765
S.H. Cho, S.W. Lee, S. Yu, H. Kim, S. Chang et al., Micropatterned pyramidal ionic gels for sensing broad-range pressures with high sensitivity. ACS Appl. Mater. Interfaces 9(11), 10128–10135 (2017). https://doi.org/10.1021/acsami.7b00398
Z. Qiu, Y. Wan, W. Zhou, J. Yang, J. Yang et al., Ionic skin with biomimetic dielectric layer templated from calathea zebrine leaf. Adv. Funct. Mater. 28(37), 1802343 (2018). https://doi.org/10.1002/adfm.201802343
N. Bai, L. Wang, Q. Wang, J. Deng, Y. Wang et al., Graded intrafillable architecture-based iontronic pressure sensor with ultra-broad-range high sensitivity. Nat. Commun. 11, 209 (2020). https://doi.org/10.1038/s41467-019-14054-9
C. Liang, J. Peng, D. Yan, L. Xue, Y. Han, Ordered porous polymer films via phase separation in humidity environment. Polymer 46(14), 5334–5340 (2005). https://doi.org/10.1016/j.polymer.2005.04.018
N. Ramakrishnan, V.S. Arunachalam, Effective elastic moduli of porous solids. J. Mater. Sci. 25, 3930–3937 (1990). https://doi.org/10.1007/BF00582462
O. Ishai, L.J. Cohen, Elastic properties of filled and porous epoxy composites. Int. J. Mech. Sci. 9(8), 539–546 (1967). https://doi.org/10.1016/0020-7403(67)90053-7
G.Z. Tan, Y. Zhou, Tunable 3D nanofiber architecture of polycaprolactone by divergence electrospinning for potential tissue engineering applications. Nano-Micro Lett. 10, 73 (2018). https://doi.org/10.1007/s40820-018-0226-0
A. Wang, Y. Hu, H. Wang, Y. Cheng, T. Thomas et al., Activating inverse spinel NiCo2O4 embedded in N-doped carbon nanofibers via Fe substitution for bifunctional oxygen electrocatalysis. Mater. Today Phys. 17, 100353 (2021). https://doi.org/10.1016/j.mtphys.2021.100353
D.H. Kim, Y. Jung, K. Jung, D.H. Kwak, D.M. Park et al., Hollow polydimethylsiloxane (PDMS) foam with a 3D interconnected network for highly sensitive capacitive pressure sensors. Micro Nano Syst. Lett. 8, 24 (2020). https://doi.org/10.1186/s40486-020-00127-8
C. Metzgera, E. Fleisch, J. Meyer, M. Dansachmüller, I. Graz et al., Flexible-foam-based capacitive sensor arrays for object detection at low cost. Appl. Phys. Lett. 92, 013506 (2008). https://doi.org/10.1063/1.2830815
J.H. Kwon, Y.M. Kim, H.C. Moon, Porous ion gel: a versatile ionotronic sensory platform for high-performance, wearable ionoskins with electrical and optical dual output. ACS Nano 15(9), 15132–15141 (2021). https://doi.org/10.1021/acsnano.1c05570
Y. Chang, L. Wang, R. Li, Z. Zhang, Q. Wang et al., First decade of interfacial iontronic sensing: from droplet sensors to artificial skins. Adv. Mater. 33(7), 2003464 (2020). https://doi.org/10.1002/adma.202003464
B.N. Persson, Contact mechanics for randomly rough surfaces. Surf. Sci. Rep. 61(4), 201–227 (2006). https://doi.org/10.1016/j.surfrep.2006.04.001
L.J. Gibson, M.F. Ashby, Cellular solids: structure and properties (U. K., Pergamon, Oxford, 1988), pp. 120–168
L. Liu, X. Feng, A. Chakma, Unusual behavior of poly (ethylene oxide)/AgBF4 polymer electrolyte membranes for olefin-paraffin separation. Sep. Purif. Technol. 38(3), 255–263 (2004). https://doi.org/10.1016/j.seppur.2003.11.013
R. Gerhardt, Impedance and dielectric spectroscopy revisited: distinguishing localized relaxation from long-range conductivity. J. Phys. Chem. Solids 55(12), 1491–1506 (1994). https://doi.org/10.1016/0022-3697(94)90575-4
A. Chorotos, Z. Bao, Skin-inspired electronic devices. Mater. Today 17(7), 321–331 (2014). https://doi.org/10.1016/j.mattod.2014.05.006
M.A. Schuetz, L.R. Glicksman, A basic study of heat transfer through foam insulation. J. Cell. Plast. 20(2), 114–121 (1984). https://doi.org/10.1177/0021955X8402000203