Self-oscillating materials

In these experiments, the volume of the confined gel is constant its main role is to damp hydrodynamical motions that would otherwise perturb the chemical intrinsic patterns. More recently it has been shown experimentally that the coupling of a volume phase transition with a chemical oscillator can generate a self-oscillating gel (i, 4). More precisely, if one of the chemical species taking part in the chemical reaction modifies the threshold for the phase transition, then the time periodic variation of this concentration can generate autonomous swelling-deswelling cycles of the gel even in absence of any external stimuli (5, 6). This device thus provides a novel biomimetic material with potential biomedical and technical applications. 

Spontaneous oscillations are a widespread phenomenon in nature. They have been studied for a large number of experiments, including electrochemical systems such as the oxidation of metals and organic materials [Miller and Chen (2006)]. Electrochemical systems exhibiting instabilities often behave like activator-inhibitor systems. In these systems the electrode potential is an essential variable and takes on the role of either activator or the inhibitor. If certain conditions are met, an activator-inhibitor system generates oscillations [Krischer (2001)]. In this section we present experimental data of electric potential self-oscillations on the electrode of IPMC which results in the oscillating actuation of the material. Furthermore, we also present a physical model to predict these oscillations. 

FIGURE 5.1.2 Development of the self-oscillating polymer as functional materials systems. 

Yoshida, R., Sakai, T., Kara, Y., Maeda, S., Hashimoto, S., Suzuki, D., Murase, Y. Self-oscillating gel as novel biomimetic materials. J. Cont. Releas. 140, 186 (2009)... 

Yoshida, R. Self-oscillating gels driven by the Belousov-Zhabotinsky reaction as novel smart materials. Mater. 2010, 22, 3463-3483. 

Kuksenok et al. in Chapter 8 consider self-oscillating gels as biomimetic soft materials. They have modeled systems that exhibit irritability, the ability to sense and respond to a potentially harmful stimulus. Specifically, they have modeled materials based on Yoshida s BZ gel systems that could emit a chemical alarm signal and directed motion in response to a mechanical deformation or impact. This could be a significant step to biomimetic materials with important applications. 

Yoshida, R. (2008) Self-oscillating polymer and gels as novel biomimetic materials. Bull. Chem. Soc.Jpn., 81, 676-688. 

Self-Oscillating Cels as Biomimetic Soft Materials... 

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