250 research outputs found
Channel-Width Dependent Enhancement in Nanoscale Field Effect Transistor
We report the observation of channel-width dependent enhancement in nanoscale
field effect transistors containing lithographically-patterned silicon
nanowires as the conduction channel. These devices behave as conventional
metal-oxide-semiconductor field-effect transistors in reverse source drain
bias. Reduction of nanowire width below 200 nm leads to dramatic change in the
threshold voltage. Due to increased surface-to-volume ratio, these devices show
higher transconductance per unit width at smaller width. Our devices with
nanoscale channel width demonstrate extreme sensitivity to surface field
profile, and therefore can be used as logic elements in computation and as
ultrasensitive sensors of surface-charge in chemical and biological species.Comment: 5 pages, 4 figures, two-column format. Related papers can be found at
http://nano.bu.ed
Bidirectional optical non-reciprocity in a multi-mode cavity optomechanical system
Optical non-reciprocity, a phenomenon that allows unidirectional flow of
optical field is pivoted on the time reversal symmetry breaking. The symmetry
breaking happens in the cavity optomechanical system (COS) due to non uniform
radiation pressure as a result of light-matter interaction, and is crucial in
building non-reciprocal optical devices. In our proposed COS, we study the
non-reciprocal transport of optical signals across two ports via three optical
modes optomechanically coupled to the mechanical excitations of two
nano-mechanical resonators (NMRs) under the influence of strong classical drive
fields and weak probe fields. By tuning different system parameters, we
discover the conversion of reciprocal to non-reciprocal signal transmission. We
reveal perfect nonreciprocal transmission of output fields when the effective
cavity detuning parameters are near resonant to the NMRs' frequencies. The
unidirectional non-reciprocal signal transport is robust to the optomechanical
coupling parameters at resonance conditions. Moreover, the cavities' photon
loss rates play an inevitable role in the unidirectional flow of signal across
the two ports. Bidirectional transmission can be fully controlled by the phase
changes associated with the incoming probe and drive fields via two ports. Our
scheme may provide a foundation for the compact non-reciprocal communication
and quantum information processing, thus enabling new devices that route
photons in unconventional ways such as all-optical diodes, optical transistors
and optical switches
Silicon-based nanochannel glucose sensor
Silicon nanochannel biological field effect transistors have been developed
for glucose detection. The device is nanofabricated from a silicon-on-insulator
wafer with a top-down approach and surface functionalized with glucose oxidase.
The differential conductance of silicon nanowires, tuned with source-drain bias
voltage, is demonstrated to be sensitive to the biocatalyzed oxidation of
glucose. The glucose biosensor response is linear in the 0.5-8 mM concentration
range with 3-5 min response time. This silicon nanochannel-based glucose
biosensor technology offers the possibility of high density, high quality
glucose biosensor integration with silicon-based circuitry.Comment: 3 pages, 3 figures, two-column format. Related papers can be found at
http://nano.bu.ed
Computation of Wind Wave Flow Field with Moving Boundary Based on Image Processing
Based on image processing technology, a solution to the interference of moving boundary in wind wave flow field calculation is proposed. Invariant background is extracted from image sequence by means of the minimum method, and the differences between image sequence and invariant background image are used to remove the invariant background of image sequence. The image segmentation threshold is determined based on maximum interclass variance method, and the scatter interference is removed by image filtering and morphological technology, to obtain the target image. Then the flow field is calculated by PIV technology and the results of the flow field before and after the boundary treatment are compared. The experimental results show that the accuracy and speed of flow field calculation are greatly improved after removal of moving boundary disturbance, and the results of wind wave flow field calculation accord with the motion mechanism of hydraulic wind wave
Nanoscale field effect transistor for biomolecular signal amplification
We report amplification of biomolecular recognition signal in lithographically defined silicon nanochannel devices. The devices are configured as field effect transistors (FET) in the reversed source-drain bias region. The measurement of the differential conductance of the nanowire channels in the FET allows sensitive detection of changes in the surface potential due to biomolecular binding. Narrower silicon channels demonstrate higher sensitivity to binding due to increased surface-to-volume ratio. The operation of the device in the negative source-drain region demonstrates signal amplification. The equivalence between protein binding and change in the surface potential is described
Field Effect Transistor Nanosensor for Breast Cancer Diagnostics
Silicon nanochannel field effect transistor (FET) biosensors are one of the most promising technologies in the development of highly sensitive and label-free analyte detection for cancer diagnostics. With their exceptional electrical properties and small dimensions, silicon nanochannels are ideally suited for extraordinarily high sensitivity. In fact, the high surface-to-volume ratios of these systems make single molecule detection possible. Further, FET biosensors offer the benefits of high speed, low cost, and high yield manufacturing, without sacrificing the sensitivity typical for traditional optical methods in diagnostics. Top down manufacturing methods leverage advantages in Complementary Metal Oxide Semiconductor (CMOS) technologies, making richly multiplexed sensor arrays a reality. Here, we discuss the fabrication and use of silicon nanochannel FET devices as biosensors for breast cancer diagnosis and monitoring
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