5,682 research outputs found
Liquid and back gate coupling effect: towards biosensing with lowest detection limit
We employ noise spectroscopy and transconductance measurements to establish
the optimal regimes of operation for our fabricated silicon nanowire
field-effect transistors (Si NW FETs) sensors. A strong coupling between the
liquid gate and back gate (the substrate) has been revealed and used for
optimisation of signal-to-noise ratio in sub-threshold as well as
above-threshold regimes. Increasing the sensitivity of Si NW FET sensors above
the detection limit has been predicted and proven by direct experimental
measurements.Comment: 18 pages, 6 figure
A high aspect ratio Fin-Ion Sensitive Field Effect Transistor: compromises towards better electrochemical bio-sensing
The development of next generation medicines demand more sensitive and
reliable label free sensing able to cope with increasing needs of multiplexing
and shorter times to results. Field effect transistor-based biosensors emerge
as one of the main possible technologies to cover the existing gap. The general
trend for the sensors has been miniaturisation with the expectation of
improving sensitivity and response time, but presenting issues with
reproducibility and noise level. Here we propose a Fin-Field Effect Transistor
(FinFET) with a high heigth to width aspect ratio for electrochemical
biosensing solving the issue of nanosensors in terms of reproducibility and
noise, while keeping the fast response time. We fabricated different devices
and characterised their performance with their response to the pH changes that
fitted to a Nernst-Poisson model. The experimental data were compared with
simulations of devices with different aspect ratio, stablishing an advantage in
total signal and linearity for the FinFETs with higher aspect ratio. In
addition, these FinFETs promise the optimisation of reliability and efficiency
in terms of limits of detection, for which the interplay of the size and
geometry of the sensor with the diffusion of the analytes plays a pivotal role.Comment: Article submitted to Nano Letter
Device modelling for bendable piezoelectric FET-based touch sensing system
Flexible electronics is rapidly evolving towards
devices and circuits to enable numerous new applications. The
high-performance, in terms of response speed, uniformity and
reliability, remains a sticking point. The potential solutions for
high-performance related challenges bring us back to the timetested
silicon based electronics. However, the changes in the
response of silicon based devices due to bending related stresses is
a concern, especially because there are no suitable models to
predict this behavior. This also makes the circuit design a
difficult task. This paper reports advances in this direction,
through our research on bendable Piezoelectric Oxide
Semiconductor Field Effect Transistor (POSFET) based touch
sensors. The analytical model of POSFET, complimented with
Verilog-A model, is presented to describe the device behavior
under normal force in planar and stressed conditions. Further,
dynamic readout circuit compensation of POSFET devices have
been analyzed and compared with similar arrangement to reduce
the piezoresistive effect under tensile and compressive stresses.
This approach introduces a first step towards the systematic
modeling of stress induced changes in device response. This
systematic study will help realize high-performance bendable
microsystems with integrated sensors and readout circuitry on
ultra-thin chips (UTCs) needed in various applications, in
particular, the electronic skin (e-skin)
Trick or Heat? Manipulating Critical Temperature-Based Control Systems Using Rectification Attacks
Temperature sensing and control systems are widely used in the closed-loop
control of critical processes such as maintaining the thermal stability of
patients, or in alarm systems for detecting temperature-related hazards.
However, the security of these systems has yet to be completely explored,
leaving potential attack surfaces that can be exploited to take control over
critical systems.
In this paper we investigate the reliability of temperature-based control
systems from a security and safety perspective. We show how unexpected
consequences and safety risks can be induced by physical-level attacks on
analog temperature sensing components. For instance, we demonstrate that an
adversary could remotely manipulate the temperature sensor measurements of an
infant incubator to cause potential safety issues, without tampering with the
victim system or triggering automatic temperature alarms. This attack exploits
the unintended rectification effect that can be induced in operational and
instrumentation amplifiers to control the sensor output, tricking the internal
control loop of the victim system to heat up or cool down. Furthermore, we show
how the exploit of this hardware-level vulnerability could affect different
classes of analog sensors that share similar signal conditioning processes.
Our experimental results indicate that conventional defenses commonly
deployed in these systems are not sufficient to mitigate the threat, so we
propose a prototype design of a low-cost anomaly detector for critical
applications to ensure the integrity of temperature sensor signals.Comment: Accepted at the ACM Conference on Computer and Communications
Security (CCS), 201
Neuro-memristive Circuits for Edge Computing: A review
The volume, veracity, variability, and velocity of data produced from the
ever-increasing network of sensors connected to Internet pose challenges for
power management, scalability, and sustainability of cloud computing
infrastructure. Increasing the data processing capability of edge computing
devices at lower power requirements can reduce several overheads for cloud
computing solutions. This paper provides the review of neuromorphic
CMOS-memristive architectures that can be integrated into edge computing
devices. We discuss why the neuromorphic architectures are useful for edge
devices and show the advantages, drawbacks and open problems in the field of
neuro-memristive circuits for edge computing
A Robust Analog VLSI Reichardt Motion Sensor
Silicon imagers with integrated motion-detection circuitry have been developed and tested for the past
15 years. Many previous circuits estimate motion by identifying and tracking spatial or temporal features. These
approaches are prone to failure at low SNR conditions, where feature detection becomes unreliable. An alternate
approach to motion detection is an intensity-based spatiotemporal correlation algorithm, such as the one proposed
by Hassenstein and Reichardt in 1956 to explain aspects of insect vision. We implemented a Reichardt motion
sensor with integrated photodetectors in a standard CMOS process. Our circuit operates at sub-microwatt power
levels, the lowest reported for any motion sensor. We measure the effects of device mismatch on these parallel,
analog circuits to show they are suitable for constructing 2-D VLSI arrays. Traditional correlation-based sensors
suffer from strong contrast dependence. We introduce a circuit architecture that lessens this dependence. We also
demonstrate robust performance of our sensor to complex stimuli in the presence of spatial and temporal noise
CMOS IMAGE SENSORS FOR LAB-ON-A-CHIP MICROSYSTEM DESIGN
The work described herein serves as a foundation for the development of CMOS imaging in lab-on-a-chip microsystems. Lab-on-a-chip (LOC) systems attempt to emulate the functionality of a cell biology lab by incorporating multiple sensing modalidites into a single microscale system. LOC are applicable to drug development, implantable sensors, cell-based bio-chemical detectors and radiation detectors. The common theme across these systems is achieving performance under severe resource constraints including noise, bandwidth, power and size. The contributions of this work are in the areas of two core lab-on-a-chip imaging functions: object detection and optical measurements
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