Soft actuator

Choi HR, Jung KM, Kwak JW, Lee SW, Kim HM, Jeon JW, Nam JD (2003) Multiple degree-of-freedom digital soft actuator for robotic applications. Proc SPIE 5051 262... 

Lee S, Jung K, Koo J, Lee S, Choi H, Heon J, Nam J, Choi H (2004) Braille display device using soft actuator. Proc SPIE 5385 368... 

Koo IM, Jung K, Koo JC, Nam JD, Lee YK, Choi HR (2008) Development of soft-actuator-based wearable tactile display. IEEE Trans Robotics 24 549... 

Shahinpoor M, Mojarrad M (2000) Soft actuators and artificial muscles. US Patent 6109852... 

S. Ramirez-Garcia and D. Diamond, Biomimetic, low power pumps based on soft actuators. Sens. Actual A, A135 (1), 229-235 (2007). 

Abstract The combination of nanomaterials and ordered deformable soft materials is emerging as an enabling system in nanoscience and nanotechnology. In this context, nanomaterial functionalized photoresponsive liquid crystalline polymers are very promising and versatile systems due to their dynamic function. Moreover, the unique characteristic of nanomaterials combined with the mechanical, self-organizing and stimuli-responsive properties of deformable liquid crystalline polymers opens up new and exciting possibilities. In this chapter, we present recent developments of photodeformable behaviors of liquid crystalline polymers functionalized with nanomaterials. The main emphasis revolves around how the physicochemical properties of different nanomaterials modulate the reversible photomechanical behaviors of liquid crystalline polymers and their potential application in devices such as optically controlled switches and soft actuators. 

In recent years, nanotechnology and nanomaterials have been widely used in designing advanced functional materials based on photoresponsive LCPs. Although several reviews have concentrated on the photodeformable effect of LCPs and their applications in soft actuators [22], to date the influence of nanostructures and nanomaterials on the photodeformable properties of LCPs has not been summarized. In this chapter, we mainly focus on the utilization of special nanostructures and amazing physicochemical properties of nanomaterials to manipulate the photomechanical behaviors of LCPs. Fmthermore, their potential applications as light-driven devices and other future prospects are proposed. 

Because of the unique photodeformable behavior of LCPs, a variety of soft actuators such as flexible inchworm walkers [34], plastic motors [35] and high-frequency oscillators [36] have been designed. For these soft photo-driven acm-ators based on LCPs, many factors determine the photo-driven behaviors of actuators, including the wavelength, polarization direction and intensity of the light source, and inherent parameters of actuators such as the concentration of azobenzene moieties, the crosslinking density and the molecular arrangement within actuators. Besides, their mechanical properties, conductivity and overall physical attributes should also be taken into consideration for practical applications (see in Fig. 10.2). 

Fig. 10.2 Influencing factors for potential applications of soft actuators based on LCPs...

Soft Actuators Based on Nanomaterials Functionalized LCPs... 

Z. Jiang, M. Xu, F.Y. Li, Y.L. Yu, Red-light controllable liquid-crystal soft actuators via low-power excited upconversion based on triplet-triplet annihilation. J. Am. Chem. Soc. 135, 16446-16453 (2013)... 

Actuators that generate movements and forces, such as bending, expansion and contraction driven by stimulation of electrical, chemical, thermal and optical energies, are different from rotating machines such as electric motors and internal combustion engines. There are many sorts of soft actuators made of polymers [1-3], gels [4] and nanotubes [5]. Particularly, biomimetic actuators are interesting because of the application to artificial muscles that will be demanded for medical equipment, robotics and replacement of human muscle in the future. 

Choi, H., Jung, K., Ryew, S., Nam, J., Jeon, J., Koo, J. and Tanie, K. (2005a). Biomimetic soft actuator Design, modelling, control and applications, lEEE/ASME Transaction on Mechatronics 10, pp. 581-593. 

Kuramata, Y., et al., 2014. Development of a colonoscope robot with multiple propulsion modes using pneumatic soft actuators. In Proceedings of BioMedical Imaging, JSMBE-BMI2013-11. 

Water swollen hydrogels are generally amorphous without any particularly ordered structure at molecular level. For many years, polymer gels have been studied for the development of low-voltage soft actuators [187-193]. As an example, they can be used to construct thermo-responsive diaphragms capable of automatically opening and closing a valve [194]. They can also show shape memory effects. For instance, a thermal activation of a shape memory gel is shown in Fig. 6.96. 

Electric field is also expected as an effective external field to drive finite and fast deformation in LCEs, because, as is well known for low molecular mass LCs (LMM-LCs), an electric field is capable of inducing fast rotation of the director toward the field direction [6]. This electrically driven director rotation results in a large and fast change in optical birefringence that is called the electro-optical (EO) effect. The EO effect is a key principle of LC displays. Electrically induced deformation of LCEs is also attractive when they are used for soft actuators a fast actuation is expected, and electric field is an easily controlled external variable. However, in general, it is difficult for LCEs in the neat state to exhibit finite deformation in response to the modest electric fields accessible in laboratories. Some chiral smectic elastomers in the neat state show finite deformation stemming from electroclinic effects [7,8], but that is beyond the scope of this article we focus on deformation by director rotation. 

Shahinpoor, M. and Mojarrad, M. (2000) Soft Actuators and Artificial Muscles, US Patent Office, US Patent 6,109,852, Issued 29 August 2000. 

Sonoda, Y., Takashima, W. and Kaneto, K. (2001) Characteristics of soft actuators based on... 

Kaneto, K., Fujisue, H., Kunifusa, M. and Takashima, W. (2007) Conducting polymer soft actuators based on polypyrrole films - energy conversion efficiency. Smart Materials and Structures, 16, S250. ... 

Lee, S., Jung, K., Koo, J., et al. Braille Display Device Using Soft Actuator, (2004) Proceedings of SPIE Smart Structures and Materials 2004 Electroactive Polymer Actuators and Devices (EAPAD) (ed. Bar-Cohen, Y.) 5385, 368-79. 

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