Page 358 - Flexible Robotics in Medicine

350 Chapter 15

changes by responding to the various stimuli such as electrical or magnetic, they are
capable of transducing to physical deformations.

Magnetic actuators may be used in biomedical applications such as capsule endoscopy [1]
and soft robots for drug delivery [2]. One way to fabricate a magnetic actuator is to
disperse magnetic particles into a polymer matrix to form a composite. Due to the magnetic
particles within, the composite material responds to the magnetic field and exhibit
movements. For different actuating behaviors, different magnetization profiles can be
induced into the composite, and changes to the field strength and directions can be made
[2]. Thus magnetic actuators show great promise for biomedical applications.
Electroactive polymer (EAP) actuators can also be utilized for its biomedical
applications, such as for artificial muscles [3]. Previous works operate in electrolytic
solutions, swollen states, or solid states but are limited by the operating environmental
conditions. A type of EAP actuator being able to perform in ambient conditions is
constructed using ionic liquid (IL) as a dielectric layer. Under the influence of the
electric field, electrophoretic polarization of the IL occurs [4]. As the larger anions move
toward one side, the smaller cations proceed to the opposite side, having one side of the
composite to be stretched while the other to be compressed. Hence, bending and
deformation occur, and actuating behavior is exhibited.

Conductive PEDOT:PSS is used as a flexible electrode for the fabrication of both the
magnetic and EAP actuators due to its biocompatibility, conductivity, and ductility [5].
PEDOT:PSS aqueous dispersion is convenient to process by a solution method. Due to such
properties, PEDOT:PSS combination has a wide range of applications even outside of the
biomedical field, such as for solar cells, supercapacitors, and thermoelectric devices [6].Thus
PEDOT:PSS serves as an excellent conductive polymer for multiple applications.

This work investigates the electrical, mechanical, and magnetic properties of magnetic
actuators and the electrical and mechanical properties of EAP actuators, namely the
electromechanical characterization of PEDOT:PSS/xylitol/Fe 3 O 4 magnetic responsive soft
actuator and IL/PVDF-HFP/PEDOT:PSS/xylitol EAP actuator. The influence of the weight
of Fe 3 O 4 nanoparticles (NPs) in the magnetic actuators on hysteresis, stress strain
relationship, and conductivity is also examined.

15.2 Experimental setup

15.2.1 Preparation of PEDOT:PSS/xylitol/Fe 3 O 4 composite films and coated
cotton thread

The aqueous solution of PEDOT:PSS was purchased from Heraeus, named Clevios PH
1000, contains 1.3 wt.% PEDOT:PSS dispersion in H 2 O with a weight ratio of 2.5 of PSS