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Workshops

Interactions and Transport of Charged Species in Bulk and at Interfaces

July 4, 2016 to July 7, 2016
Location : CECAM-AT

Soft Matter Manipulated by Ionic Redistribution: Hydrogel-Based Circuits, Biomimetic Devices and Soft Robotic Actuators

Orlin D. Velev


Abstract

The live tissue is a complex hydrogel-like material, whose functions, such as muscle actuation and neural transduction are accomplished by ionic currents and metabolite transport through vascular "microfluidic" networks. We will discuss how the principles of ionic transport and electroosmotic actuation can be transcribed into hydrogel-based biomimetic devices [1]. Earlier, we reported a new class of gel diodes with rectifying junction formed by interfacing water-based gels doped with polyelectrolytes of opposite charge [2-4] and showed how water-based gels doped with photosensitive polyelectrolytes can be used as the core of novel photovoltaic cells [5]. We demonstrated that these concepts could be applied in the making of bioinspired "artificial leaves" with microvascular channel networks embedded in permeable hydrogel, and reported experimental and modelling results of self-regenerating dye sensitized solar cells [6]. We will then discuss how ionic transport, electrostatic crosslinking, and osmotic pressure gradients can also be used in novel hydrogel actuators and soft robotic components. The first example is based on our "ionoprinting" technique that allows directed and reversible hydrogel bending by directional ion injection [7]. A second type of hydrogel actuator can be built on electroosmotic ion redistribution through a bi-gel system [8]. Finally we will present the ongoing work on hydrogel devices combined with colloidal assemblies [9,10]. Such devices that can be ionically actuated and reconfigured by electrical or chemical means may find applications in new types of actuators and soft robotic components.



References

[1] H.-J. Koo and O. D. Velev, Biomicrofluidics, 7, 031501, 1 (2013).
[2] O. J. Cayre, S.-T. Chang and O. D. Velev, J. Am. Chem. Soc. 129, 10801 (2007).
[3] H.-J. Koo, S.-T. Chang and O. D. Velev, Small, 6, 1393-1397 (2010).
[4] H.-J. Koo, J.-H. So, M. D. Dickey, O. D. Velev, Adv. Mater, 23, 3559 (2011).
[5] H.-J. Koo, S. T. Chang, J. M. Slocik, R. R. Naik and O. D. Velev J. Mater. Chem., 21, 72 (2011).
[6] H.-J. Koo and O. D. Velev, Sci. Rep. (Nat.), 3, 2357, 1 (2013).
[7] E. Palleau, D. Morales, M. D. Dickey and O. D. Velev, Nature Comm., 4, 2257, 1 (2013).
[8] D. Morales, E. Palleau, M. D. Dickey and O. D. Velev, Soft Matter, 10, 1337 (2014).
[9] B. Bharti and O. D. Velev, Langmuir, 31, 7897 (2015).
[10] D. Morales, B. Bharti, M. D. Dickey and O. D. Velev, Small, 12, 2283 (2016).