An ideal plastic actuator for haptic applications should generate a relatively large displacement (minimum 0.2-0.6 mm,
force (~50 mN/cm2) and a fast actuation response to the applied voltage. Although many different types of flexible,
plastic actuators based on electroactive polymers (EAP) are currently under investigation, the ionic EAPs are the only
ones that can be operated at low voltage. This property makes them suitable for applications that require inherently safe
actuators. Among the ionic EAPs, bucky gel based actuators are very promising. Bucky gel is a physical gel made by
grounding imidazolium ionic liquids with carbon nanotubes, which can then be incorporated in a polymeric composite
matrix to prepare the active electrode layers of linear and bending actuators. Anyhow, many conflicting factors have to
be balanced to obtain required performance. In order to produce high force a large stiffness is preferable but this limits
the displacement. Moreover, the bigger the active electrode the larger the force. However the thicker an actuator is, the
slower the charging process becomes (it is diffusion limited). In order to increase the charging speed a thin electrolyte
would be desirable, but this increases the probability of pinholes and device failure. In this paper we will present how
different approaches in electrolyte and electrode preparation influence actuator performance and properties taking
particularly into account the device ionic conductivity (which influences the charging speed) and the electrode surface
resistance (which influences both the recruitment of the whole actuator length and its speed).
In previous papers, we reported the first dry actuator that can be fabricated simply by layer-by-layer casting, using
'bucky gel', a gelatinous room-temperature ionic liquid containing single-walled carbon nanotubes (SWNTs). The
actuator has a bimorph configuration with a polymer-supported internal ionic liquid electrolyte layer sandwiched by
polymer-supported bucky-gel electrode layers, which allow quick and long-lived operation in air at low applied voltages.
In this paper, some of the recent developments of the actuator performance are reported.
We demonstrate an extremely efficient chemical vapour deposition synthesis of single-walled carbon nanotubes where
the activity and lifetime of the catalysts are enhanced by controlling the ambient of the CVD furnace, a growth mode we
call "Super Growth" [1]. The enhanced catalytic activity of super growth results in massive growth of super-dense and
vertically-aligned single-walled nanotubes forests with heights up to 2.5 millimeters. In addition, these SWNT forests
were easily separated from the catalysts, producing the most pure SWNT material (over 99.98%) ever made, through an
all-dry process without any purification. Moreover, patterned highly organized intrinsic single-walled nanotube
structures were successfully fabricated. Super Growth simultaneously addresses many critical problems such as
scalability, purity, and cost, and opens up innumerable opportunities ranging from fundamental research to real
applications.
Conference Committee Involvement (9)
Carbon Nanotubes, Graphene, and Emerging 2D Materials for Electronic and Photonic Devices IX
28 August 2016 | San Diego, California, United States
Carbon Nanotubes, Graphene, and Emerging 2D Materials for Electronic and Photonic Devices VIII
9 August 2015 | San Diego, California, United States
Carbon Nanotubes, Graphene, and Associated Devices VII
20 August 2014 | San Diego, California, United States
Carbon Nanotubes, Graphene, and Associated Devices VI
28 August 2013 | San Diego, California, United States
Carbon Nanotubes, Graphene, and Associated Devices V
14 August 2012 | San Diego, California, United States
Carbon Nanotubes, Graphene, and Associated Devices IV
23 August 2011 | San Diego, California, United States
Carbon Nanotubes, Graphene, and Associated Devices III
1 August 2010 | San Diego, California, United States
Carbon Nanotubes, Graphene, and Associated Devices II
5 August 2009 | San Diego, California, United States
Carbon Nanotubes and Associated Devices
10 August 2008 | San Diego, California, United States
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