4 research outputs found
Transparent, Flexible Strain Sensor Based on a Solution-Processed Carbon Nanotube Network
The demands for transparent,
flexible electronic devices are continuously increasing due to their
potential applications to the human body. In particular, skin-like,
transparent, flexible strain sensors have been developed to realize
multifunctional human–machine interfaces. Here, we report a
sandwich-like structured strain sensor with excellent optical transparency
based on highly purified, solution-processed, 99% metallic CNT–polydimethylÂsiloxane
(PDMS) composite thin films. Our CNT–PDMS composite strain
sensors are mechanically compliant, physically robust, and easily
fabricated. The fabricated strain sensors exhibit a high optical transparency
of over 92% in the visible range with acceptable sensing performances
in terms of sensitivity, hysteresis, linearity, and drift. We also
found that the sensitivity and linearity of the strain sensors can
be controlled by the number of CNT sprays; hence, our sensor can be
applied and controlled based on the need of individual applications.
Finally, we investigated the detections of human activities and emotions
by mounting our transparent strain sensor on various spots of human
skins
Three-Dimensional Printed Poly(vinyl alcohol) Substrate with Controlled On-Demand Degradation for Transient Electronics
Electronics that degrade after stable
operation for a desired operating time, called transient electronics,
are of great interest in many fields, including biomedical implants,
secure memory devices, and environmental sensors. Thus, the development
of transient materials is critical for the advancement of transient
electronics and their applications. However, previous reports have
mostly relied on achieving transience in aqueous solutions, where
the transience time is largely predetermined based on the materials
initially selected at the beginning of the fabrication. Therefore,
accurate control of the transience time is difficult, thereby limiting
their application. In this work, we demonstrate transient electronics
based on a water-soluble polyÂ(vinyl alcohol) (PVA) substrate on which
carbon nanotube (CNT)-based field-effect transistors were fabricated.
We regulated the structural parameters of the PVA substrate using
a three-dimensional (3D) printer to accurately control and program
the transience time of the PVA substrate in water. The 3D printing
technology can produce complex objects directly, thus enabling the
efficient fabrication of a transient substrate with a prescribed and
controlled transience time. In addition, the 3D printer was used to
develop a facile method for the selective and partial destruction
of electronics
Three-Dimensionally Printed Micro-electromechanical Switches
Three-dimensional
(3D) printers have attracted considerable attention from both industry
and academia and especially in recent years because of their ability
to overcome the limitations of two-dimensional (2D) processes and
to enable large-scale facile integration techniques. With 3D printing
technologies, complex structures can be created using only a computer-aided
design file as a reference; consequently, complex shapes can be manufactured
in a single step with little dependence on manufacturer technologies.
In this work, we provide a first demonstration of the facile and time-saving
3D printing of two-terminal micro-electromechanical (MEM) switches.
Two widely used thermoplastic materials were used to form 3D-printed
MEM switches; freely suspended and fixed electrodes were printed from
conductive polylactic acid, and a water-soluble sacrificial layer
for air-gap formation was printed from polyÂ(vinyl alcohol). Our 3D-printed
MEM switches exhibit excellent electromechanical properties, with
abrupt switching characteristics and an excellent on/off current ratio
value exceeding 10<sup>6</sup>. Therefore, we believe that our study
makes an innovative contribution with implications for the development
of a broader range of 3D printer applications (e.g., the manufacturing
of various MEM devices and sensors), and the work highlights a uniquely
attractive path toward the realization of 3D-printed electronics
Three-Dimensional Fin-Structured Semiconducting Carbon Nanotube Network Transistor
Three-dimensional
(3-D) fin-structured carbon nanotube field-effect
transistors (CNT-FETs) with purified 99.9% semiconducting CNTs were
demonstrated on a large scale 8 in. silicon wafer. The fabricated
3-D CNT-FETs take advantage of the 3-D geometry and exhibit enhanced
electrostatic gate controllability and superior charge transport.
A trigated structure surrounding the randomly networked single-walled
CNT channel was formed on a fin-like 3-D silicon frame, and as a result,
the effective packing density increased to almost 600 CNTs/ÎĽm.
Additionally, highly sensitive controllability of the threshold voltage
(<i>V</i><sub>TH</sub>) was achieved using a thin back gate
oxide in the same silicon frame to control power consumption and enhance
performance. Our results are expected to broaden the design margin
of CNT-based circuit architectures for versatile applications. The
proposed 3-D CNT-FETs can potentially provide a desirable alternative
to silicon based nanoelectronics and a blueprint for furthering the
practical use of emerging low-dimensional materials other than CNTs