Low-voltage actuator

The varieties of different carbon structures offer a great basis for EAPs. They are most widely used electrode materials in low-voltage actuation generation. So far, carbon nanotubes (CNTs) have gained unrivaled attention. Their popularity is... 

C.L. Dai and J.H. Chen, Low voltage actuated RF micromechanical switches fabricated using CMOS-MEMS technique. Microsystem Technologies, Vol. 12, pp. 1143-1151, 2006. 

Y.W. Mo, Y.Z. Okawa, K.J. Inoue, and K. Natukawa. Low-voltage and low-power optimization of micro-heater and its on-chip drive circuitry for gas sensor array . Sensors and Actuators AlOO (2002), 94-101. 

G. Ferri, P.D. Laurentiis, A. D Amico and C.D. Natale, A low-voltage integrated CMOS analog lock-in amplifier prototype for LAPS applications, Sens. Actuators A Phys., 92(1-3) (2001) 263-272. 

On the other hand, nanotube actuators can work at low voltages and temperatures as high as 350 °C. For example, maximum stress observed in SWNTs is 26MPa, a value that is 100 times larger than that observed in natural muscles. 

Aschwanden M, Stemmer A (2007) Low voltage, highly tunable diffraction grating based on dielectric elastomer actuators. Proc SPIE 6524 6524IN... 

Ionic Polymeric Metallic Composites (IPMCs) are a class of EAPs that exhibit characteristics of both actuators and sensors, Shahinpoor et al. [6—11]. The flexibility of an IPMC makes it possible to be applied both in small and large deflection applications. Successive photographs of an IPMC strip are shown in Fig. 2.1 that demonstrates very large deformation (up to 8 cm) in the presence of low voltage. The sample is 10 mm wide, 80 mm long, and 0.34 mm thick. The time interval is 1 s and the actuation voltage is 4 V DC. 

Chen, L., Liu, C., Liu, K., Meng, C., Hu, C., Wang, J., Fan, S., 2011. High-performance, low-voltage, and easy-operable bending actuator based on aligned carbon nanotube/polymer composites. ACS Nano 5, 1588-1593. 

However, the electrical conductivity of the carbon nanomaterials is vulnerable to degradation due to the inefficient dispersion in a large-scale actuator. To this end, some metallic additives have been incorporated into the carbon-based electrode to enhance the electrical conductivity and actuation stability For instance, for the IPMC actuator where the reduced graphene oxide was used as electrode, the electrical conductivity of the electrodes could be efficiently improved after introduction of Ag nanoparticles (Fig. 8.2E) (Lu et al., 2013). As a result, both the actuation frequency and stability could be improved. Upon application of a low voltage of 1V, the actuator could be driven at a wide frequency range (0.01-10 Hz), and no obvious decrease in displacement was observed over 500 cycles of actuation. 

Lee HC, et al. Piezoelectrically actuated RF MEMS DC contact switches with low voltage operation. IEEE Microwave and Guided Wave Lett 2005. 

The purpose of this book is to provide a focused, in-depth, yet self-contained treatment of recent advances made in several most promising EAP materials. In particular, the book covers two classes of ionic EAPs, ionic polymer-metal composites (IPMCs) and conjugated polymers, and one class of electronic EAP materials, dielectric elastomers. Ionic EAPs realize actuation through ion transport, and thus require very low voltages (a few volts) to operate, but their bandwidths are typically lower than tens of Hz. On the other hand, dielectric elastomers rely on electrostatic forces to operate and thus require high actuation voltages (kilovolts), but... 

In 2005, aerospace company, Diehl Luftfahrt Elektronik GmbH adopted EDLCs to power emergency actuation systems for doors and evacuation slides in airliners, including the new Airbus 380 jumbo jet. As of 2007 all solid state micrometer-scale electric double-layer capacitors based on advanced superionic conductors had been developed for low-voltage electronics. 

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. 

---