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ABSTRACT Typically, electroresponsive hydrogels have either a high electrical conductivity with little swelling or large swelling with low conductivity. This paper investigates a method of maintaining high swelling capabilities and increasing electrical conductivity by infusing multiwalled carbon nanotubes (MWCNTs) into a hydrolyzed polyacrylamide hydrogel. Various concentrations of MWCNT and Nafion solutions infused into the hydrogel were investigated. Optical microscopy analysis showed aggregates of carbon nanotube bundles at the macroscale, whereas electron microscopy revealed homogeneous dispersion of carbon nanotube in the polymer matrix at the microscale. Electrical conductivity measurements demonstrated an increase from 0.02 to 0.11 mS cm-1 with infused MWCNT. The MWCNT-infused hydrogels demonstrated a 400% increase in deswelling capabilities during an applied electrical stimulus compared to a noninfused hydrogel. In conclusion, infusing the MWCNT into the hydrogel increased its electrical conductivity, which allows the hydrogel to deswell more rapidly with an applied electrical bias without compromising its mechanical or swelling properties. [ABSTRACT FROM AUTHOR]

ABSTRACT Electro-responsive hydrogels (ERH) are highly researched materials for biomedical applications. However, most of the research is concentrated on the synthesis of novel hydrogels for various applications, and little effort has been made to investigate electrode configuration and optimization of electrical stimulation parameters. This article used a three-dimensional interdigitated (IDT) electrode configuration device to investigate the optimization of electrical actuation parameters in order to radially deswell an ERH. A Pluronic-bismethacrylate hydrogel modified with hydrolyzed methacrylic acid was used as the ERH material. This article reports on using novel electro-actuation parameters and electrode configurations to maximize radial deswelling of an ERH for biomedical applications. The optimal waveform was assessed for, varying electrode spacing's, voltages, duty cycles, and frequencies. The results show that a maximum deswelling occurred with a DC pulsed monophasic waveform, with IDT electrodes spaced close enough to create a relatively uniform electric field, with a peak voltage of 5 V at 1 kHz, and 50% duty cycle. This resulted in a deswelling of 320% in Krebs solution. Electrochemical impedance spectroscopy results show that the impedance is dependent on the ionic concentration of the fluid environment and that the impedance decreases with increasing frequency. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41687. [ABSTRACT FROM AUTHOR]

ABSTRACT Stimuli-responsive hydrogels are continuing to increase in demand in biomedical applications. Occluding a blood vessel is one possible application which is ideal for a hydrogel because of their ability to expand in a fluid environment. However, typically stimuli-responsive hydrogels focus on bending instead of radial uniform expansion, which is required for an occlusion application. This article focuses on using an interdigitated electrode device to stimulate an electro-responsive hydrogel in order to demonstrate a uniform swelling/deswelling of the hydrogel. A Pluronic-bismethacrylate (PF127-BMA) hydrogel modified with hydrolyzed methacrylic acid, in order to make it electrically responsive, is used in this article. An interdigitated electrode device was manufactured containing Platinum electrodes. The results in this paper show that the electrically biased hydrogels deswelled 230% more than the non-biased samples on average. The hydrogels deswelled uniformly and showed no visual deformations due to the electrical bias. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1523-1528 [ABSTRACT FROM AUTHOR]