title: Parylene-coated ionic liquid-carbon nanotube actuators for user-safe haptic devices.
abstract: Simple fabrication, high power-to-weight and power-to-volume ratios, and the ability to operate in open air at low voltage make the ionic electroactive polymer actuators highly attractive for haptic applications. Whenever a direct tactile stimulation of the skin is involved, electrical and chemical insulation as well as a long-term stability of the actuator are required. Because of its inherent physicochemical properties such as high dielectric strength, resistance to solvents, and biological inactivity, Parylene C meets the requirements for making biocompatible actuators. We have studied the displacement and the generated force of Parylene-coated carbon nanotube actuators as well as the encapsulation quality. A 2 μm coating creates an effective electrical insulation of the actuators without altering the blocking force at frequencies from 50 mHz to 1 Hz. Moreover, the generated strain is preserved at higher frequencies (from 0.5 to 5 Hz). We employed a simple mechanical model to explain the relation between the key parameters-flexural stiffness, displacement, and force-for uncoated and coated actuators. In addition, we demonstrated that our Parylene-coated actuators are not damaged by rinsing in liquid media such as 2-propanol or water. In conclusion, our results indicate that Parylene C encapsulated actuators are safe to touch and can be used in contact with human skin and in biomedical applications in direct contact with tissues and physiological fluids.
authors.affiliation: †Istituto Italiano di Tecnologia, Robotics, Brain and Cognitive Sciences Department, Via Morego 30, Genoa, Italy, 16163.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Bubak
authors.affiliation: †Istituto Italiano di Tecnologia, Robotics, Brain and Cognitive Sciences Department, Via Morego 30, Genoa, Italy, 16163.
authors.forename: David
authors.initials: D
authors.lastname: Gendron
authors.affiliation: ‡Istituto Italiano di Tecnologia, Smart Materials, Via Morego 30, Genoa, Italy, 16163.
authors.forename: Luca
authors.initials: L
authors.lastname: Ceseracciu
authors.affiliation: †Istituto Italiano di Tecnologia, Robotics, Brain and Cognitive Sciences Department, Via Morego 30, Genoa, Italy, 16163.
authors.forename: Alberto
authors.initials: A
authors.lastname: Ansaldo
authors.affiliation: †Istituto Italiano di Tecnologia, Robotics, Brain and Cognitive Sciences Department, Via Morego 30, Genoa, Italy, 16163.
authors.forename: Davide
authors.initials: D
authors.lastname: Ricci
mesh_terms: D025802:Electric Capacitance; D004553:Electric Conductivity; D052578:Ionic Liquids / Q000737:chemistry*; D008422:Materials Testing; D037742:Nanotubes, Carbon / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D014992:Xylenes / Q000737:chemistry*
chemical_list: D052578:Ionic Liquids; D037742:Nanotubes, Carbon; D011108:Polymers; D014992:Xylenes; C011055:parylene
keywords: Parylene coating; actuators; carbon nanotubes; composite materials; ionic liquid