TY  - GEN
Y1  - 2024///
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/34624/
AV  - public
CY  - Heidelberg
TI  - Tailoring Actuation Properties of
Thermoresponsive Hydrogels and
Implementation into Soft Robotic
Applications
ID  - heidok34624
N2  - Soft material robotics relies on the development of responsive, soft materials and
requires high standards, with respect to the material properties: High responsivity,
robust mechanical properties, high cycle times, and fast responses are some
examples for these requirements, which are rarely found in such responsive, soft
materials, and thus need to be adjusted by material engineering.
This thesis addresses tailoring the properties of thermoresponsive hydrogels and
implementing these materials into soft robotic applications. Furthermore, a thorough
investigation of material responsivity and mechanical properties is conducted,
which are crucial parameters for the development of soft actuators.
First, a template-assisted fabrication method based on sacrificial zinc oxide templates
is introduced, which yields microporous and highly thermoresponsive hydrogels.
Compared to its conventional bulk counterpart, this material exhibits a
large volume transition and generates considerable stroke forces upon stimulation,
which are crucial requirements for actuator applications. These changes in thermoresponsive
actuation properties result from the increased surface area created
by the microporosity of the hydrogel. Actuation capabilities are demonstrated on
the basis of a soft, thermally controlled gripper.
Based on the previous findings, two-photon 3D laser printing is used to fabricate
responsive hydrogel microactuators with precise control of actuator surfaceto-
volume ratio and to investigate actuation capabilities as a function of actuator
design and fabrication parameters. It turns out that miniaturization of the actuators
and especially the surface-to-volume-ratio have a major impact on responsivity.
In addition, variation of the processing parameters during fabrication is
found to be a facile strategy for tailoring actuator properties, such as stiffness and
responsivity. Moreover, the assembly of individual actuators into microactuator
systems, enables cooperative functions, such as capturing and releasing cargo in a
microfluidic chip upon thermal stimulation.
The micro engineering strategies presented in this work, provide a toolkit for
understanding the science of thermo-actuation and tailoring actuation properties
of responsive hydrogels. Furthermore, methods for developing soft robotic applications
at the microscale using such hydrogels are demonstrated.
A1  - Spratte, Tobias
ER  -