Bilayer and trilayer actuators

Bilayer and Trilayer Actuators Operating in a Liquid Electrolyte. 416... 

Bilayer and trilayer actuators Characterizations of Electrochemical cell Experimental procedure Materials Conducting polymers (CPs) Liquid electrolyte Open air Cyclic voltammetry Dibutyltin dilaurate Electronic conducting polymers (ECPs) Interpenetrating polymer network (IPN) Poly (3,4-ethylenedioxythiophene) (PEDOT) Polypyrrole (PPY) Actuation mechanism of Electrogeneration of Electropolymerization of pyrrole monomer Oxidation and reduction reaction of Polyvinylidene fluoride (PVDF) Solid polymer electrolyte (SPE) membrane Force characterizations IPNs Load curves and metrics PVDF membrane Strain characterizations... 

Figure 15.1 Conducting-polymer actuation based upon bending of a bilayer or trIlayer actuator in which S-SO-jim-thick polymer layers are typically grown on a metal-coated Inert support the linear stretching of a free-standing film, of several mm to cm in length and the out-of-plane actuation of conducting-polymer films...

Empirical results Irom bending bilayer or trilayer actuators corroborate that the described angle (angle) is under linear control of the charge (Q) consxuned by the conducting polymer film reaction (Otero and Sansinena 1997 Otero and Cortes 2004 Conzuelo et al. 2010 Valero et al. 2011) ... 

Wu Y, Alici G, Madden JDW, Spinks GM, Wallace GG (2007) Soft mechanical sensors through reverse actuation in polypyrrole. Adv Funct Mater 17 3216-3222 Zainudeen UL, Careem MA, Skaamp S (2007) Actuators based on pedot and PPy conducting polymer bilayers and trilayers. In Industrial and information systems, 2007. ICIIS 2007. International conference on, 9-11 Aug 2007. Peradeniya, pp 461-464 Zhou D, Wallace GG, Spinks GM, Liu L, Cowan R, Saunders E, Newbold C (2003) Actuators for the cochlear implant Synth Met 135-136 39-40... 

For both, bilayer and trilayer devices, the experimental setup is quite similar (Figs. 3 and 4). The actuator is immersed in a liquid electrolyte, ensuring proper eleetrieal conductivity (a metallic clamp can be used for example, as mentioned before). In die case of the bilayer device, a reference electrode and a counter-electrode are needed. These electrodes need to have proper connections too. Each of the electrodes are directly connected to the proper inputs of a potentiostat-galvanostat, able to apply and measure simultaneously cxurent and potential waves. Applied waves are controlled by a computer. The measured signals are also recorded. For the three-layer device, the reference electrode and counter-electrode inputs of the potentiostat are shortcut and connected directly to the second active layer of conducting polymer. The connections of the two different conducting polymer layers must be independent, ensuring proper isolation between them. 

The bilayer deviee requires a eounter-electrode to allow the current flow, expending there most of the consumed electrical energy. Trilayer actuators (Fig. 2b) use two CP films, electrode and counter-electrode, with cooperative actuation due to opposed volume variations during current flow, increasing the effieieney of the aetuator (Han and Shi 2004 Ahci and Huynh 2006 John et al. 2008 Yao et al. 2008 Zainudeen et al. 2008 Garcia-Cordova et al. 2011). 

Fig. 2 Schematic structure of bending actuators, (a) bilayer and (b) trilayer actuators operating in liquid electrolyte, (c) trilayer and (d) pseudo-trilayer actuators containing their own electrolyte and operating in open-air. fVB working electrode, CE counter-electrode. Ref reference electrode. ECP electronic conducting polymer, PVDF Polyvinylidenefluoride. IPN interpenetrating polymer network...

PPy trilayers microactuators have been laser cut with lateral sizes down to 200 pm long and 50 pm wide. They have been made with a commercial PVDF membrane or spin-coated PVDF thin film, having a total actuator thickness of 126 and 48 pm, respectively. Since they are composed of a shghtly thicker PPy layer than the bilayer microactuators, their speeds are lower too, 0.1-0.6 Hz. The measured blocking force is up to 600 pN (see Gaihre et al. 2011b, 2012). 

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