In this paper, a CMOS on-chip sensor is presented to detect dielectric constant of organic chemicals. The dielectric constant of these chemicals is measured using the oscillation frequency shift of an LC voltage-controlled oscillator (VCO) upon the change of the tank capacitance when exposed to the liquid. To make the system self-sustained, the VCO is embedded inside a frequency synthesizer to convert the frequency shift into voltage that can be digitized using an on-chip analog-to-digital converter. The dielectric constant is then estimated using a detection procedure including the calibration of the sensor. The dielectric constants of different organic liquids have been detected in the frequency range of 7-9 GHz with an accuracy of 3.7% compared with theoretical values for sample volumes of 10-20 μL. The sensor is also applicable for binary mixture detection and estimation of the fractional volume of the constituting materials with an accuracy of 1%-2%.

A Self-Sustained CMOS Microwave Chemical Sensor Using a Frequency Synthesizer

In this paper, a miniaturized broadband dielectric spectroscopy system is presented for permittivity detection, chemical sensing, and mixture characterization for 1-8-GHz frequency range. A sensing capacitor exposed to the material under test (MUT) is part of a true time-delay (TTD) cell excited by a microwave signal at the sensing frequency of interest. The phase shift of the microwave signal at the output of the TTD cell compared to its input is a measure of the permittivity of MUTs. For wideband and accurate sensing, TTD cells are cascaded in a reconfigurable fashion to increase the detected phase shift, especially at low frequencies. TTD cells are designed to detect permittivities within the range of 1-30 considering nonideal effects, such as electromagnetic coupling between adjacent TTD cells. Calibration using reference liquids is applied to the fabricated sensor and sensor characteristics are extracted. Permittivity detection of organic chemicals is performed in the range of 1-8 GHz with an error less than 2%. The measured permittivities in the 1-8-GHz range are used to estimate the sub-1-GHz permittivities of MUTs using extrapolation. The sensing system is also used for mixture characterization to find the mixing ratios in binary mixtures with an accuracy of 1%.

A 1–8-GHz Miniaturized Spectroscopy System for Permittivity Detection and Mixture Characterization of Organic Chemicals

Recent multi-disciplinary research focuses on expanding the use of integrated electronic circuits and systems in nonelectrical applications such as chemical/biomedical sensors. The global trend in this area is moving toward portable, implantable, and lab-on-chip systems that require 1) complete integration of the system-on-silicon platforms, such as complementary-metal-oxide-semiconductor (CMOS) processes, and 2) self-sustained implementation to achieve stand-alone operation without the need for any external equipment. In other words, self-sustained, integrated systems are necessary for portable and implantable sensors.

Integrated Systems for Biomedical Applications: Silicon-Based RF\/Microwave Dielectric Spectroscopy and Sensing

From DNA to protein: Why genetic code context of nucleotides for DNA signal processing? A review

Fermi-Dirac distribution for doped semiconductors and Burstein-Moss effect have been correlated first time to figure out the conductivity type of ZnO. Hall Effect in the Van der Pauw configuration has been applied to reconcile our theoretical estimations which evince our assumption. Band-gap narrowing has been found in all p-type samples, whereas blue Burstein-Moss shift has been recorded in the n-type films. Atomic Force Microscopic (AFM) analysis shows that both p-type and n-type films have almost same granular-like structure with minor change in average grain size (∼ 6 nm to 10 nm) and surface roughness rms value 3 nm for thickness ∼315 nm which points that grain size and surface roughness did not play any significant role in order to modulate the conductivity type of ZnO. X-ray diffraction (XRD), Energy Dispersive X-ray Spectroscopy (EDS) and X-ray Photoelectron Spectroscopy (XPS) have been employed to perform the structural, chemical and elemental analysis. Hexagonal wurtzite structure has been observed in all samples. The introduction of nitrogen reduces the crystallinity of host lattice. 97% transmittance in the visible range with 1.4 × 107 Ω-1cm-1 optical conductivity have been detected. High absorption value in the ultra-violet (UV) region reveals that NZOs thin films can be used to fabricate next-generation high-performance UV detectors.

/pdf/acceptor-modulated-optical-enhancements-and-band-gap-57c1fwckmz.pdf

Acceptor-modulated optical enhancements and band-gap narrowing in ZnO thin films

Gene prediction is an important topic in genomic research Various techniques are in use for identification of protein coding regions in genes Application of Fourier technique is one of the most popular methods of gene prediction, in which prediction algorithm is based on period-3 property of DNA where it exhibits a prominent peak in coding region Spectrum estimation by Fourier method generates various harmonics, generally known as 1/f noise along with sharp peaks, which may lead to false prediction of coding regions Researchers used various parametric and non-parametric filters to tackle this problem and improve the accuracy of prediction Performance of anti-notch filter with cascaded lattice structure on one hand and harmonic suppressor with comb filter on the other hand have been compared here for identification of coding regions of C-elegan F56F114a chromosome The authors have analyzed the performance in terms of standard deviation and signal-to-noise ratio A Matlab simulink environment has been used for filter realization and performance analysis

Performance analysis and simulation of IIR anti-notch filter with various structures for gene prediction application

This work describes and evaluates a technique for determining dielectric
properties, and presents results of dielectric measurement of some substances. Dielectric
properties of some known dielectric materials are first measured and verified with our
technique and then applied to conducting polymer materials. A non-destructive method
based on the shift in resonance frequency and quality factor measurement of a resonant
cavity placing a small-sized sample is used. Dielectric constant and loss factor
measurement is performed with the aid of Spectrum Analyzer in the frequency range
from 8GHZ to 12GHz. 3-D EM simulation studies using HFSS 11 software of the cavity
with loading is compared with the measurement. The results indicated that using the
resonant cavity with the technique is suitable for dielectric parameter measurement for
small shaped medium loss samples having thickness in the range 4-6mm at X-Band
frequencies.

Measurement of dielectric properties of medium loss samples at X-band frequencies

The cavity perturbation method is widely used in the study of electromagnetic properties of dielectric materials at X-band frequencies. It works well for the measurement of low-loss and medium loss materials. In this paper an easy and reliable method is discussed for the accurate determination of the dielectric constant of medium loss samples such as Teflon and Perspex.

A simple technique for the measurement of the permittivity of medium loss samples using cavity perturbation method

The performance characteristics of a 35-GHz cavity stabilized Gunn diode oscillator is presented. The frequency variations are found to be reduced by a factor of 66 when the oscillator is locked to the cavity. © 1994 John Wiley & Sons, Inc.

Cavity stabilized Gunn oscillator at 35 GHz

A technique has been designed to determine the relative permittivity and dielectric loss of low loss materials using a cylindrical cavity resonator at X band. This technique has been tested over some standard materials with satisfactory results compared to some existing standard methods for measuring tanS. The measurements are performed TE111 mode with the aid of Agilent E4418B EPM series power meter and Agilent 53150A 20 GHz frequency counter.

http://www.jmpee.org/jmpee_site/Vol494/JMPEE494207Mondal.pdf

Salil Kumar Biswas

Papers

Performance analysis and simulation of IIR anti-notch filter with various structures for gene prediction application

Measurement of dielectric properties of medium loss samples at X-band frequencies

A simple technique for the measurement of the permittivity of medium loss samples using cavity perturbation method

Cavity stabilized Gunn oscillator at 35 GHz

A Novel Technique to Measure Small Dielectric Losses Using Cylindrical Cavity Resonator at X Band