Three-dimensional (3D) printing technology is one of
the additive
manufacturing (AM) technologies that brings exciting prospects to
the realm of conjugated polymers (CPs) and organic electronics through
vastly enhanced design flexibility, structural complexity, and environmental
sustainability. However, the use of 3D printing for CPs is still at
early stages and remains full of challenges. Therefore, an interesting
approach is to produce 3D-printed electrically conductive materials
by exploiting the photopolymerization of conjugated monomers directly
during the stereolithography process. The idea proposed in this work
is to formulate a printable ink containing aniline able to photopolymerize
within the insulating printable polyethylene glycol diacrylate (PEGDA)
polymeric matrix directly during the 3D-printing process. The produced
PEGDA-polyaniline (PANI) composites exhibit suitable morphological
and structural features, as well as electrical and electrochemical
performances potentially useful for various soft electronics applications.
As a proof of concept, the 3D printed PEGDA-PANI samples are employed
as a soft electrode in an electrocardiogram (ECG) device, and the
efficiency is monitored under real-time conditions. The collected
data exhibit reproducible ECG patterns, opening the way to 3D printed
PEGDA-PANI electrodes for biosignal monitoring applications.
This study is devoted to synthesizing and modifying conductive Ti‐doped diamond (TiD) biosubstrates with polyaniline (PANI) to provide a soft interface with high ionic conductivity and charge storage capacity for developing advanced scaffolds and implantable electrode materials. The diamond supports are prepared by an ad‐hoc chemical vapor deposition methodology allowing for the synthesis and contemporary doping of diamond lattice. An optimized potentiostatic electropolymerization method assures the growth of a homogenous PANI coating on a diamond surface. Scanning electron microscopy, atomic force microscopy, Raman, and reflectance infrared spectroscopy characterizations guarantee the production of nanostructured diamond layers with high surface electrical conductivity and good phase quality as well as of a rough polymer film in the conductive emeraldine form. Cyclic voltammetry and electrochemical impedance spectroscopy measurements point out a quasi‐reversible electron transfer among polymer chains ruled by the bulky dodecyl sulfate anion chosen as polymer dopant. This induces a cation exchange with the solution upon backbone redox reactions. The capability of the PANI‐TiD system to transduce ionic current into electronic current and vice versa via redox reaction with the surroundings can be reliably exploited to reproduce electrical stimulation processes through which to mimic the original bioelectricity functions of the human body for advanced biomedical applications.
Electrically conductive scaffolds, mimicking the unique directional alignment of muscle fibers in the myocardium, are fabricated using the 3D printing micro-stereolithography technique. Polyethylene glycol diacrylate (photo-sensitive polymer), Irgacure 819 (photo-initiator), curcumin (dye) and polyaniline (conductive polymer) are blended to make the conductive ink that is crosslinked using free radical photo-polymerization reaction. Curcumin acts as a liquid filter and prevents light from penetrating deep into the photo-sensitive solution and plays a central role in the 3D printing process. The obtained scaffolds demonstrate well defined morphology with an average pore size of 300 ± 15 μm and semi-conducting properties with a conductivity of ~ 10–6 S/m. Cyclic voltammetry analyses detect the electroactivity and highlight how the electron transfer also involve an ionic diffusion between the polymer and the electrolyte solution. Scaffolds reach their maximum swelling extent 30 min after immersing in the PBS at 37 °C and after 4 weeks they demonstrate a slow hydrolytic degradation rate typical of polyethylene glycol network. Conductive scaffolds display tunable conductivity and provide an optimal environment to the cultured mouse cardiac progenitor cells.
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