Self-oscillating motion

Self-Beating Artificial Cells Design of Cross-Linked Polymersomes Showing Self-Oscillating Motion... 

The vortex-induced oscillation contributes mainly to the lower frequency range of the spectrum. This phenomenon becomes more notable as the wind speed increases since the vortex shedding frequency is proportional to the wind speed and it will be closer to the fundamental frequency of the East Asian Hall. However, self-excited motion is not expected since the vortex-shedding oscillation frequency is far from the resonant frequencies of the building [203]. 

Ciliary Motion Actuator Using Self-Oscillating Gel... 

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. 

Self-Oscillating Gel Conveyers Autonomous Mass Transport Surface Using Peristaltic Motion of the Gels... 

To construct an autonomous mechanical pumping system such as intestines, we fabricated a self-oscillating gel in a tubular shape by photopolymerization (Fig. 5.1.4) [50]. Several types of tubular self-oscillating gels that exhibit autonomous peristaltic motion were... 

FIGURE 5.1.5 (a) Schematic illustration of autonomous pulsatile flow by peristaltic motion of a tubular self-oscillating gel. (b) Distribution of the velocity vector in the tubular self-oscillating gel during the autonomous peristaltic motion. 

Murase, Y Maeda, S. Hashimoto, S. Yoshida, R. Design of amass transport surface utilizing peristaltic motion of a self-oscillating gel. Langmuir 2009, 25, 483 89. 

Shiraki, Y Yoshida, R. Autonomous intestine-like motion of tubular self-oscillating gel. Angew. Chem. Int. Ed. 2012, 51, 6112-6116. 

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. 

Microfabrication of self-oscillating gel has also been attempted by lithography for application to a ciliary motion actuator (artificial cilia) [30]. The gel membrane with microprojection array on the surface was fabricated by utilizing X-lay lithography (LIGA). With the propagation of chemical wave, the microprojection array exhibits dynamic rhythmic motion hke ciha. The actuator may also serve as a microconveyor. 

T. (2003) Self-beating motion of gels and modulation of oscillation rhythm synchronized with organic acid. Macromolecules, 36, 1759-1761. 

Ciliary motion actuator using self-oscillating gel. Sens. Actuators A, 95, 234-238. 

Some additional circuitry is then required to improve the transient response and prevent a possible self-oscillation of the servo system. Several techniques for this are possible. A simple one consists of including a second feedback loop to add a small force proportional to the time derivative of the mass displacement, i.e., the mass velocity. This allows the feedback force to control the mass motion in advance, and the servo loop is stabilized. 

Tabata O, Hirasawa H, Aoki S, Yoshida R, Koknliita E (2002) Ciliary motion actuator using self-oscillating gel. Sens Actuators, A 95 234—238... 

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