3 research outputs found
Direct Writing and Characterization of Three-Dimensional Conducting Polymer PEDOT Arrays
Direct writing is
an effective and versatile technique for three-dimensional
(3D) fabrication of conducting polymer (CP) structures. It is precisely
localized and highly controllable, thus providing great opportunities
for incorporating CPs into microelectronic array devices. Herein we
demonstrate 3D writing and characterization of polyÂ(3,4-ethylenedioxythiophene)-polystyrenesulfonate
(PEDOT:PSS) pillars in an array format, by using an in-house-constructed
variant of scanning ion conductance microscopy (SICM). CP pillars
with different aspect ratios were successfully fabricated by optimizing
the writing parameters: pulling speed, pulling time, concentration
of the polymer solution, and the micropipette tip diameter. Especially,
super high aspect ratio pillars of around 7 μm in diameter and
5000 μm in height were fabricated, indicating a good capability
of this direct writing technique. Additions of an organic solvent
and a cross-linking agent contribute to a significantly enhanced water
stability of the pillars, critical if the arrays were to be used in
biologically relevant applications. Surface morphologies and structural
analysis of CP pillars were characterized by scanning electron microscopy
and Raman spectroscopy, respectively. Electrochemical properties of
the individual pillars of different heights were examined by cyclic
voltammetry using a double-barrel micropipette as an electrochemical
cell. Exceptional mechanical properties of the pillars, such as high
flexibility and robustness, were observed when bent by applying a
force. The 3D pillar arrays are expected to provide versatile substrates
for functionalized and integrated biological sensing and electrically
addressable array devices
A Label-Free, Sensitive, Real-Time, Semiquantitative Electrochemical Measurement Method for DNA Polymerase Amplification (ePCR)
Oligonucleotide hybridization to
a complementary sequence that
is covalently attached to an electrochemically active conducting polymer
(ECP) coating the working electrode of an electrochemical cell causes
an increase in reaction impedance for the ferro-ferricyanide redox
couple. We demonstrate the use of this effect to measure, in real
time, the progress of DNA polymerase chain reaction (PCR) amplification
of a minor component of a DNA extract. The forward primer is attached
to the ECP. The solution contains other PCR components and the redox
couple. Each cycle of amplification gives an easily measurable impedance
increase. Target concentration can be estimated by cycle count to
reach a threshold impedance. As proof of principle, we demonstrate
an electrochemical real-time quantitative PCR (e-PCR) measurement
in the total DNA extracted from chicken blood of an 844 base pair
region of the mitochondrial Cytochrome c oxidase gene, present at
∼1 ppm of total DNA. We show that the detection and semiquantitation
of as few as 2 copies/μL of target can be achieved within less
than 10 PCR cycles
Molecularly Engineered Intrinsically Healable and Stretchable Conducting Polymers
Advances
in stretchable electronics concern engineering of materials
with strain-accommodating architectures and fabrication of nanocomposites
by embedding a conductive component into an elastomer. The development
of organic conductors that can intrinsically stretch and repair themselves
after mechanical damage is only in the early stages yet opens unprecedented
opportunities for stretchable electronics. Such functional materials
would allow extended lifetimes of electronics as well as simpler processing
methods for fabricating stretchable electronics. Herein, we present
a unique molecular approach to intrinsically stretchable and healable
conjugated polymers. The simple yet versatile synthetic procedure
enables one to fine-tune the electrical and mechanical properties
without disrupting the electronic properties of the conjugated polymer.
The designed material is comprised of a hydrogen-bonding graft copolymer
with a conjugated backbone. The morphological changes, which are affected
by the composition of functional side chains, and the solvent quality
of the casting solution play a crucial role in the synthesis of highly
stretchable and room-temperature healable conductive electronic materials