**Author details**

244 Smart Actuation and Sensing Systems – Recent Advances and Future Challenges

The advantages of using IPMC as electrolysis generator in depth control device are: 1) quiet gas generation; 2) low activation voltage; 3) compact design. The challenge arises from the low gas generation rate. In the close-loop depth control (Chen et al, 2012b), a fast gas generation rate is required to compensate the depth drop caused by disturbances and the volume decrease caused by water pressure, rapidly. A multi-IPMC electrodes design might be a good solution to increase the gas generation. However, it also increases the power consumption. In our future work, an additional volume-fixed gas storage chamber will be used to collect the generated gas with high pressure. Another solenoid valve will be used to release the high pressure gas into the gas chamber, which controls the volume of the device rapidly. One may be aware of hydrogen and oxygen explosive gas in the gas storage chamber. A two-gas-chamber design can solve this issue by separating oxygen and hydrogen gases. If a fuel cell is embedded, these gases can be recycled as fuel to recharge the battery, which makes the depth control more power

In this Chapter, we presented two studies on IPMC artificial muscles in bio-inspired engineering research. In the first study, we developed a bio-inspired robotic manta ray powered by IPMC pectoral fin. We developed a novel synthesis process to fabricate IPMC pectoral fin that is capable of 3D kinematic motion and characterized the pectoral fin in terms of tip deflection (up to 100%), bode plot (0.4 Hz cut-off frequency), twist angle (up to 40o), and power consumption (below 1.5 W). A small size free-swimming robotic manta ray has been developed and experimental results have demonstrated its free-swimming capability with speed at 0.067 body length per second and 2.5 W power consumption. In the second study, we developed a novel buoyancy control device as an artificial swimming bladder. IPMC acted as an efficient, environmentally friendly water electrolysis generator to gain volume of the device while a solenoid valve was used as gas releasing controller. A compact and low power device has been assembled with an on-board open loop controller. Experimental results have shown that the device was able to control its 0.9 m depth within 3

In both studies, advantages and challenges of IPMC in bio-inspired engineering research have been addressed. In this first study, the advantages of using IPMC as artificial muscle are: 1) low actuation voltage; 2) working well in wet condition; 3) low noise; 4) simple mechanical structure; 5) able to be shaped into bio-inspired engineering design. The disadvantages are: 1) low generated force; 2) slow response time. The challenge in this study comes from optimal design of the pectoral fin. In future research, we will focus on modeling an IPMC powered pectoral fin and modeling of the fluid dynamics introduced by the 3D kinematic motions of the fin. In the second study, the advantages of using IPMC as electrolysis generator are: 1) low noise; 2) compact design; 3) low

*3.3.3. Discussion* 

efficient.

minutes.

**4. Chapter conclusion** 

Zheng Chen, T. Um and Hilary Bart-Smith\* *University of Virginia, USA* 
