There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

A review on carbon nanotubes and graphene as fillers in reinforced polymer nanocomposites

Neuromorphic computing has come to refer to a variety of brain-inspired computers, devices, and models that contrast the pervasive von Neumann computer architecture This biologically inspired approach has created highly connected synthetic neurons and synapses that can be used to model neuroscience theories as well as solve challenging machine learning problems The promise of the technology is to create a brain-like ability to learn and adapt, but the technical challenges are significant, starting with an accurate neuroscience model of how the brain works, to finding materials and engineering breakthroughs to build devices to support these models, to creating a programming framework so the systems can learn, to creating applications with brain-like capabilities In this work, we provide a comprehensive survey of the research and motivations for neuromorphic computing over its history We begin with a 35-year review of the motivations and drivers of neuromorphic computing, then look at the major research areas of the field, which we define as neuro-inspired models, algorithms and learning approaches, hardware and devices, supporting systems, and finally applications We conclude with a broad discussion on the major research topics that need to be addressed in the coming years to see the promise of neuromorphic computing fulfilled The goals of this work are to provide an exhaustive review of the research conducted in neuromorphic computing since the inception of the term, and to motivate further work by illuminating gaps in the field where new research is needed

A Survey of Neuromorphic Computing and Neural Networks in Hardware.

http://ieeexplore.ieee.org/iel5/5/31324/01456901.pdf

Microelectronic circuits

We have reviewed the humidity sensors based on ceramic materials. We first discuss the operating principle of ceramic humidity sensors. This is followed by a section on the relationship between the conduction mechanism and microstructure characteristics of the sensing elements of ceramic humidity sensors. This part of the review is also focused on the methods for optimization of the microstructure of ceramic porous elements. The next section summarizes the information on the materials used for the ceramic humidity sensors fabrication and effect of dopants or hybrid compositions on the sensing ceramic-based materials. Then we analyze state-of-the-art techniques for producing ceramic sensors. The key research and technological challenges in the field are discussed at the end of the review. The review is based on 424 references published during from 1998–2013.

Recent trends of ceramic humidity sensors development: A review

Sensitivity is an important parameter of any humidity sensor. In recent times, nanostructure materials have been used to fabricate the capacitive-type humidity sensors to improve the sensit...

Fabrication of an anodized porous alumina relative humidity sensor with improved sensitivity

A linear, simple, and reliable capacitive temperature sensor is fabricated with inexpensive materials. The sensor is a parallel plate capacitor, in which the dielectric material polydimethylsiloxne (PDMS) is sensitive to temperature. The sensor works on the principle that the density of sensing layer decreases with an increase in temperature following the Clausius–Mosotti equation, because of which the permittivity also decreases. Moreover, the thickness of the sensing layer also increases with an increase in temperature due to a positive coefficient of linear expansion. The sensor is tested in the range of 20 °C–200 °C and shows a mean sensitivity ( $\mu$ ) of 156 fF/°C with standard deviation ( $\sigma$ )± 0.037 pF. It shows a linear characteristic with the coefficient of correlation ( $R^{2})~0.99$ , and maximum nonlinearity is 1.11% at 10 kHz. The measured resolution of the sensor is 0.08 °C, and the time constant for a unit step input is 0.6 s/°C. The average repeatability index ( $\Re$ ) of the sensor is 0.51% over a month. Finally, an interfacing circuit based on the integrator and instrumentation amplifier is designed, which gives a DC output with a sensitivity of 67.9 mV/°C.

A Novel Linear Capacitive Temperature Sensor Using Polydimethylsiloxane

Porous silicon based piezoresistive pressure sensor has been designed, fabricated and tested in the range of 0 to 1 bar and temperature range of 20/spl deg/C to 80/spl deg/C. A suitable signal conditioning analog circuit consisting of constant current generator and an offset adjustable low noise instrumentation amplifier has been designed and tested. The analog output is then digitized through an ADC and fed to FPGA. Architecture for compensation of nonlinear temperature dependence of pressure sensor has been implemented and tested in FPGA. A device model of porous silicon pressure sensor has also been developed with a view to realize a SMART pressure sensor.

Design, fabrication, testing and simulation of porous silicon based smart MEMS pressure sensor

Surface Acoustic Wave (SAW) based device is very much suitable for detecting very small quantity of vapors of explosive chemicals. There are three possible kinds of SAW devices which can be used for sensor fabrication such as delay lines, resonator and filter. Choice among them depends on individual preferences and sometimes it is the matter of chance. In this report, a high frequency 70 MHz SAW device has been developed for the detection of chemical warfare (CW) agents. SAW device is fabricated on ST-quartz substrate as it has negligible temperature coefficient at room temperature. The device is having dual oscillator circuit configuration for compensating the effects of temperature, humidity and pressure. Device is coated with suitable polymer and the applicability of the sensor for dimethyl methylphosphonate (DMMP) detection has been demonstrated.

High Frequency Surface Acoustic Wave (SAW) Device for Toxic Vapor Detection: Prospects and Challenges

A robust signal conditioning circuit for capacitive sensors, based on the dual-slope and phase-sensitive-detection technique, is presented in this article. The circuit is designed to measure the capacitance of the leaky capacitive sensors. The phase-sensitive-detection technique mitigates the effect of the shunting conductance. In addition, the circuit is designed in such a way that the error due to the parasitic/stray capacitance on the measurement of the sensor capacitance is negligible. Furthermore, an autotuning frequency-independent quadrature phase-shifter circuit is designed for an accurate 90° phase generation. A prototype of the circuit is built and tested. The experimental results show that the designed circuit can measure the sensor capacitance in the range from 65 to 528 pF with accuracy within ±1%. The robustness of the proposed circuit is tested against the variation in the amplitude and frequency of input sinusoidal excitation signal. The results confirm that the proposed circuit is well suited for sensors, such as capacitive humidity sensors, water level detection sensors, and fingerprint sensors.

Tarikul Islam

Papers

Fabrication of an anodized porous alumina relative humidity sensor with improved sensitivity

A Novel Linear Capacitive Temperature Sensor Using Polydimethylsiloxane

Design, fabrication, testing and simulation of porous silicon based smart MEMS pressure sensor

High Frequency Surface Acoustic Wave (SAW) Device for Toxic Vapor Detection: Prospects and Challenges

A Dual-Slope-Based Capacitance-to-Time Signal Conditioning Circuit for Leaky Capacitive Sensors