An electroless-microwave method is described here in order to synthesize electrically conductive gold
nano-wires on a DNA. The electrical characterization shows that the gold wires were formed on the
DNA. The nanowires were continuous, having low contact resistance, and exhibited the Ohmic
behavior of electrodes. These nanowires were found to be in a few micrometers long having the
diameter of 10-15 nm in solution and 20-30 nm in immobilized DNA with resistivity comparable to
pure metal. The nanowires fabricated here could be used as building blocks for functional
nanodevices, sensors, and optoelectronics.
We investigate effects of bending stress on piezoelectric properties of polyvinylidene fluoride (PVDF) as a polymer
sensor. The sensor was designed and fabricated into a special size and shape so that it can be attached to small
insects, such as the American cockroach (Periplaneta Americana) to measure the insects' locomotion. The
performance of the sensor is studied using a controlled linear stage to buckle the sensor mimicking the bending of
the sensor due to the leg movements of cockroaches. For comparison, a roach robot was used for multi-leg study.
Results indicate that buckling motion of the sensor produce an output that is different from regular stretching effect.
The sensor-generated charge depends on the localized stress distribution and dipole alignment. This paper discusses
the methods of characterization of piezoelectricity useful for insect applications.
The scanning probe microscopy-based (SPM) lithography techniques have presented significant challenges in fabricating
nanostructures. Using this technique with assistance of pulse current, direct deposition or oxidation can be introduced on
material surfaces. In present research, we use an atomic force microscope (AFM) to write a solid (gold) feature onto a
substrate (silicon) in ambient environment. During the contact-sliding, the material on the gold (Au) tip transferred onto
the surface of the single crystalline silicon (Si). This transfer takes place atomically as shown on a smoothly worn Au tip.
This process is almost as simple as writing a line with a pencil. Dispersion of thermal energy inducted through friction is
discussed in this presentation.
Pneumatic tires are critical components in mobile systems that are widely used in our lives for passenger and
goods transportation. Wheel/ground interactions in these systems play an extremely important role for not only
system design and efficiency but also safe operation. However, fully understanding wheel/ground interactions
is challenging because of high complexity of such interactions and the lack of in situ sensors. In this paper, we
present the development of a tire tread deformation sensor and energy harvester for real-time tire monitoring and
control. Polyvinylidene fluoride (PVDF) based micro-sensor is designed and fabricated to embed inside the tire
tread and to measure the tread deformation. We also present a cantilever array based energy harvester that takes
advantages of the mechanical bandpass filter concept. The harvester design is able to have a natural frequency
band that can be used to harvest energy from varying-frequency vibrational sources. The energy harvester
is also built using with new single crystal relaxor ferroelectric material (1 - &Vkgr;)Pb(Mg1/3Nb2/3)O3-&Vkgr;PbTiO3 (PMN-PT) and interdigited (IDT) electrodes that can perform the energy conversion more efficiently. Some
preliminary experiment results show that the performance of the sensor and the energy harvester is promising.
Piezoelectric materials have been widely used in applications such as transducers, acoustic components, as well as
motion, pressure and airborne sensors. Because of the material's biocompatibility and flexibility, we have been able to
apply small piezoelectric sensors, made of PVDF, to cockroaches. We built a laboratory test system to study the
piezoelectric properties of a bending sensor. The tested motion was compared with that of the sensor attached to a
cockroach. Surface characterization and finite element analysis revealed the effects of microstructure on piezoelectric
response. The sensor attachment enables us to monitor the insects' locomotion and study their behaviors. The
applications of engineering materials to insects opens the door to innovating approaches to integrating biological,
mechanical and electrical systems.