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In the present study, a novel sulfonated poly(vinyl alcohol)/polypyrrole polymer membrane sandwiched between platinum (SPVA-Py-Pt) is fabricated for a bending actuator which can be used in microrobotic applications. To examine the suitability of SPVA-Py-Pt based ionic polymer metal composite (IPMC) for microrobotic applications, ion exchange capacity (IEC), water uptake, proton conductivity, water loss, cyclic voltammetry (CV), linear sweep voltammetry (LSV), Fourier transform infrared spectroscopy (FTIR), thermal stability, and tip displacement studies are performed. The water holding capacity of the IPMC membrane is found to be 82.23% at room temperature for 8 h of immersion time. The IEC and proton conductivity of the IPMC membrane is found to be 1.2 meq g−1 and 1.6 × 10−3 S cm−1, respectively. Maximum water loss from IPMC is achieved as 31% at 5 V for a time period of 16 min. Based on electromechanical characterization, the maximum tip displacement of SPVA-Py-Pt IPMC (size 30 mm length, 10 mm width, 0.08 mm thickness) is 18.5 mm at 5.25 V. The major advantages of this new type of IPMC are good film-forming capability, short processing time, low cost of fabrication, good flexibility, high thermo-mechanical stabilities, good ion exchange and water holding capacities and proton conductivity as compared to other types of IPMC actuators. The comparison with other type of IPMC actuators is also summarized. A multi SPVA-Py-Pt IPMC based micro-gripping system is developed that shows the potential of microrobotic applications.

This paper presents the development of new cost-effective hybrid-type sulfonated poly(1,4-phenylene ether-ether-sulfone) (SPEES) and functionalized single-walled carbon nanotubes (SWNT) based actuators produced by the film-casting method followed by chemical reduction of Pt ions as electrodes. The preparation of SPEES was investigated in details and sulfonation of polymer was characterized by ion exchange capacity (IEC), Fourier-transform infrared (FTIR) and degree of sulfonation measurements. SPEES having degree of sulfonation of 126% was blended with SWNT and used to fabricate IPMC actuator. The chemical composition and detailed structure of SPEES-SWNT ionic polymer membranes were confirmed by FTIR, EDX and transmittance electron microscopy (TEM) analysis. Scanning electron microscopy (SEM) micrographs revealed the homogeneously distributed layers of Pt electrodes on the surfaces of IPMC membrane. The electrochemical and electromechanical properties of SPEES-SWNT-Pt-based IPMC actuator shows a better actuation performance than conventional IPMC actuators in terms of higher IEC, Proton conductivity, higher current density, electrochemical impedance spectroscopy (EIS), and large bending deflection. The robust, flexible and mechanically strong membranes prepared by the synergistic combination of SPEES and SWNT may have considerable potential as actuator materials for robotic and biomimetic applications.

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