Rapid Preparation of Novel Ionic Polymer–Metal Composite for Improving Humidity Sensing Effect

Abstract

Ionic polymer–metal composites (IPMCs) have attracted attention in recent years due to their integration of actuation and sensing functions. As one of the main sensing functions of IPMCs, humidity sensing has been of consistent interest in wearable health monitors and artificial skin. However, there are still some technical challenges in that classical IPMCs have poor humidity sensing performance due to their dense surface electrode, and IPMCs are damaged easily due to an electrode/membrane mismatch. In this work, through the spraying and electrodepositing process, we developed an efficient method to rapidly prepare a Au-shell-Ag-NW (silver nanowire)-based IPMC with high strength, low surface resistance and excellent humidity sensing performance. Meanwhile, we optimized the preparation method by clarifying the influence of solvent type and electrodepositing time on the performance of the Au-shell-Ag-NW-based IPMC, thus effectively improving the humidity sensing effect and strength of the IPMC. Compared with previous research, the humidity electrical response (~9.6 mV) of the Au-shell-Ag-NW-based IPMC is at least two orders of magnitude higher than that of the classical IPMC (~0.41 mV), which is mainly attributed to the sparse gap structure for promoting the exchange of water molecules in the environment and Nafion membrane, a low surface resistance (~3.4 Ohm/sq) for transmitting the signal, and a seamless connection between the electrode and Nafion membrane for fully collecting the ion charges in the Nafion membrane. Additionally, the Au-shell-Ag-NW-based IPMC could effectively monitor the human breathing process, and the humidity sensing performance did not change after being exposed to the air for 4 weeks, which further indicates that the Au-shell-Ag-NW-based IPMC has good application potential due to its efficient preparation technology, high stability and good reproducibility.

Self-standing bacterial cellulose-reinforced poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) doped with graphene oxide composite electrodes for high-performance ionic electroactive soft actuators

“…1–7 Specifically, smart cm-scale soft robots using IEAP materials possess bionic characteristics which are preferable to typical rigid actuators because of their flexibility, simple construction, miniaturization, safety, biocompatibility, and low energy consumption. 1,6,8–11 Typical IEAPs are ionic polymer metal composites (IPMCs), which are composed of a central ion-exchange polymer ( e.g. , Nafion, Flemion, and Aciplex) and electroless plated metal electrodes ( e.g.…”

“…, Pd, Pt, Ag, and Au) on both sides. 9–17 Under an external electric field, the hydrated cations in Nafion flow towards the cathode through the ion nanochannels, causing the cathode side to swell and eventually bend toward the anode.…”

“…[1][2][3][4][5][6][7] Specically, smart cm-scale so robots using IEAP materials possess bionic characteristics which are preferable to typical rigid actuators because of their exibility, simple construction, miniaturization, safety, biocompatibility, and low energy consumption. 1,6,[8][9][10][11] Typical IEAPs are ionic polymer metal composites (IPMCs), which are composed of a central ionexchange polymer (e.g., Naon, Flemion, and Aciplex) and electroless plated metal electrodes (e.g., Pd, Pt, Ag, and Au) on both sides. [9][10][11][12][13][14][15][16][17] Under an external electric eld, the hydrated cations in Naon ow towards the cathode through the ion nanochannels, causing the cathode side to swell and eventually bend toward the anode.…”

“…1,6,[8][9][10][11] Typical IEAPs are ionic polymer metal composites (IPMCs), which are composed of a central ionexchange polymer (e.g., Naon, Flemion, and Aciplex) and electroless plated metal electrodes (e.g., Pd, Pt, Ag, and Au) on both sides. [9][10][11][12][13][14][15][16][17] Under an external electric eld, the hydrated cations in Naon ow towards the cathode through the ion nanochannels, causing the cathode side to swell and eventually bend toward the anode.…”

Gold nanowire mesh electrode for electromechanical device

“…Although some researchers utilized silver (Ag) or copper nanowires for IPMC actuators 13 , 14 , these nanowires are easily oxidized by (electro)chemical reaction. Au-NW, which has excellent chemical stability 15 – 17 , is suitable for the electrode material of IPMC actuators. Y. Wang reported rapid preparation of IPMC humidity sensor with Au-shell-Ag-NW by spraying and electrodepositing 15 .…”