3D conductive materials such as polymers and hydrogels
that interface
between biology and electronics are actively being researched for
the fabrication of bioelectronic devices. In this work, short-time
(5 s) photopolymerizable conductive inks based on poly(3,4-ethylenedioxythiophene)
(PEDOT):polystyrene sulfonate (PSS) dispersed in an aqueous matrix
formed by a vinyl resin, poly(ethylene glycol) diacrylate (PEGDA)
with different molecular weights (
M
n
=
250, 575, and 700 Da), ethylene glycol (EG), and a photoinitiator
have been optimized. These inks can be processed by Digital Light
3D Printing (DLP) leading to flexible and shape-defined conductive
hydrogels and dry conductive PEDOTs, whose printability resolution
increases with PEGDA molecular weight. Besides, the printed conductive
PEDOT-based hydrogels are able to swell in water, exhibiting soft
mechanical properties (Young’s modulus of ∼3 MPa) similar
to those of skin tissues and good conductivity values (10
–2
S cm
–1
) for biosensing. Finally, the printed conductive
hydrogels were tested as bioelectrodes for human electrocardiography
(ECG) and electromyography (EMG) recordings, showing a long-term activity,
up to 2 weeks, and enhanced detection signals compared to commercial
Ag/AgCl medical electrodes for health monitoring.