Chandrika Sreekantan Anoop

Bio: Chandrika Sreekantan Anoop is an academic researcher from Indian Institute of Space Science and Technology. The author has contributed to research in topics: Signal conditioning & Electronic circuit. The author has an hindex of 9, co-authored 52 publications receiving 254 citations. Previous affiliations of Chandrika Sreekantan Anoop include Indian Space Research Organisation & Indian Institute of Technology Kharagpur.

A health monitoring system using multiple non-contact ECG sensors for automotive drivers

Abstract: Health and alert-level monitoring of automotive driver is very important to reduce the number of vehicle accidents and associated fatalities. The proposed work focuses on the development of a reliable and low-cost health monitoring system for automotive drivers. It is based on non-contact electrocardiogram (ECG) principle. Multiple signal acquisition ECG electrodes are placed on the seat and seat-belt of the automotive. The signals from the different electrodes are interfaced to simple analog and digital signal processing units through a switching logic. The frequency domain-based digital processing and the switching logic ensures that best quality ECG signal is selected for heart rate (HR) estimation. A prototype of the proposed system is build and tested on several volunteers. These tests show that the accuracy is 2 bpm. Additional tests to determine the system performance in various conditions was conducted and results reported.

New Signal Conditioning Circuit for MR Angle Transducers With Full-Circle Range

Abstract: An efficient signal conditioning (SC) scheme that helps to obtain a linear output from a magnetoresistive (MR) angle sensor for 0 $^{\circ}$ –360 $^{\circ}$ range is presented in this paper. Most of the existing MR angle sensors have a sine/cosine relationship between the output and sensing angle, but a linear characteristic will be very useful. The new SC circuit of the proposed transducer accepts and processes output signals from an MR sensor that is sine/cosine in nature and gives an output directly proportional to the sensing angle. The sensitivity of the transducer output to variations in different circuit and mechanical parameters has been analyzed in detail, and their effect has been quantified. The functionality of the SC has been studied using SPICE simulations. A prototype of the proposed SC circuit has been built and tested using emulated sensor output signals. The output of the prototype circuit was linear from 0 $^{\circ}$ to 360 $^{\circ}$ , and worst case error was less than 0.08%. An angle sensor unit has been built using an MR sensor IC, interfaced to the SC circuit and tested. As expected, the output was found to be linear for a full-circle range.

Electronic Scheme for Computing Inverse-Cosine and its Application to a GMR Based Angle Sensor

Abstract: This paper presents a new, simple but effective, electronic method to obtain inverse-cosine of an electrical variable. The proposed method is very useful for linearization of sensors whose output is a cosine or sine function of the physical quantity being sensed. The inverse-cosine of the variable is obtained by comparing it with a reference sinusoidal wave. The proposed method is easy to implement using electronic components. Using the new technique, a giant magneto-resistance-based angle sensor that provides an output linearly proportional to the angle being sensed has been developed, and the details are reported in this paper. A prototype of the angle sensor has been built, and the practicality of the new method has been tested successfully. The developed sensor provides a linear output for a range of 0° to 180°. The worst case error was found to be less than 0.35° for a range of 10°-170°.

Non-invasive heart rate monitoring system using giant magneto resistance sensor

Abstract: A simple heart rate (HR) monitoring system designed and developed using the Giant Magneto-Resistance (GMR) sensor is presented in this paper. The GMR sensor is placed on the wrist of the human and it provides the magneto-plethysmographic signal. This signal is processed by the simple analog and digital instrumentation stages to render the heart rate indication. A prototype of the system has been built and test results on 26 volunteers have been reported. The error in HR estimation of the system is merely 1 beat per minute. The performance of the system when layer of cloth is present between the sensor and the human body is investigated. The capability of the system as a HR variability estimator has also been established through experimentation. The proposed technique can be used as an efficient alternative to conventional HR monitors and is well suited for remote and continuous monitoring of HR.

Simple and Efficient Relaxation-Oscillator-Based Digital Techniques for Resistive Sensors — Design and Performance Evaluation

Abstract: This article proposes simple relaxation-oscillator-based digital interfacing schemes for resistive sensors in single-element and quarter-bridge forms. The proposed interfaces, equipped with novel compensation techniques, render a direct-digital output proportional to sensor resistance. These interfaces offer many meritorious features, such as simplicity of design, nonrequirement of the reference voltage, lower execution time, and negligible influences from circuit nonidealities. The methodology of the interfaces and their design criteria and error analysis are described in this article. The first two interfaces are suitable for nonremote resistive sensors, while the third interface has been developed for remotely located resistive sensors. The functionality of the proposed interfaces has been verified using simulation as well as detailed experimental studies. The developed interfaces provide a linear direct-digital output, and the maximum experimental nonlinearity is merely 0.08%. Later, a representative sensor based on the giant magnetoresistance (GMR) phenomenon is selected, characterized, and tested with the developed interfaces. The complete instrumentation system is shown to act as a linear digital magnetometer. Finally, the performance of the developed interfaces is compared and shown to be better/comparable with respect to the existing works.

Sensor Technologies for Intelligent Transportation Systems.

Abstract: Modern society faces serious problems with transportation systems, including but not limited to traffic congestion, safety, and pollution. Information communication technologies have gained increasing attention and importance in modern transportation systems. Automotive manufacturers are developing in-vehicle sensors and their applications in different areas including safety, traffic management, and infotainment. Government institutions are implementing roadside infrastructures such as cameras and sensors to collect data about environmental and traffic conditions. By seamlessly integrating vehicles and sensing devices, their sensing and communication capabilities can be leveraged to achieve smart and intelligent transportation systems. We discuss how sensor technology can be integrated with the transportation infrastructure to achieve a sustainable Intelligent Transportation System (ITS) and how safety, traffic control and infotainment applications can benefit from multiple sensors deployed in different elements of an ITS. Finally, we discuss some of the challenges that need to be addressed to enable a fully operational and cooperative ITS environment.

Magnetic nanoparticles in nanomedicine: a review of recent advances.

Abstract: Nanomaterials, in addition to their small size, possess unique physicochemical properties that differ from bulk materials, making them ideal for a host of novel applications. Magnetic nanoparticles (MNPs) are one important class of nanomaterials that have been widely studied for their potential applications in nanomedicine. Due to the fact that MNPs can be detected and manipulated by remote magnetic fields, it opens a wide opportunity for them to be used in vivo. Nowadays, MNPs have been used for diverse applications including magnetic biosensing (diagnostics), magnetic imaging, magnetic separation, drug and gene delivery, and hyperthermia therapy, etc. Specifically, we reviewed some emerging techniques in magnetic diagnostics such as magnetoresistive (MR) and micro-Hall (μHall) biosensors, as well as the magnetic particle spectroscopy, magnetic relaxation switching and surface enhanced Raman spectroscopy (SERS)-based bioassays. Recent advances in applying MNPs as contrast agents in magnetic resonance imaging and as tracer materials in magnetic particle imaging are reviewed. In addition, the development of high magnetic moment MNPs with proper surface functionalization has progressed exponentially over the past decade. To this end, different MNP synthesis approaches and surface coating strategies are reviewed and the biocompatibility and toxicity of surface functionalized MNP nanocomposites are also discussed. Herein, we are aiming to provide a comprehensive assessment of the state-of-the-art biological and biomedical applications of MNPs. This review is not only to provide in-depth insights into the different synthesis, biofunctionalization, biosensing, imaging, and therapy methods but also to give an overview of limitations and possibilities of each technology.

Magnetic nanoparticles in nanomedicine

Abstract: Nanomaterials, in addition to their small size, possess unique physicochemical properties that differ from the bulk materials, making them ideal for a host of novel applications. Magnetic nanoparticle (MNP) is one important class of nanomaterials that have been widely studied for their potential applications in nanomedicine. Due to the fact that MNPs can be detected and manipulated by remote magnetic fields, it opens a wide opportunity for them to be used in vivo. Nowadays, MNPs have been used for diverse applications including magnetic biosensing (diagnostics), magnetic imaging, magnetic separation, drug and gene delivery, and hyperthermia therapy, etc. This review aims to provide a comprehensive assessment of the state-of-the-art biological and biomedical applications of MNPs. In addition, the development of high magnetic moment MNPs with proper surface functionalization has progressed exponentially over the past decade. Herein, we also reviewed the recent advances in the synthesis and surface coating strategies of MNPs. This review is not only to provide in-depth insights into the different synthesis, biofunctionalization, biosensing, imaging, and therapy methods but also to give an overview of limitations and possibilities of each technology.

Mobile healthcare for automatic driving sleep-onset detection using wavelet-based EEG and respiration signals.

Abstract: Driving drowsiness is a major cause of traffic accidents worldwide and has drawn the attention of researchers in recent decades. This paper presents an application for in-vehicle non-intrusive mobile-device-based automatic detection of driver sleep-onset in real time. The proposed application classifies the driving mental fatigue condition by analyzing the electroencephalogram (EEG) and respiration signals of a driver in the time and frequency domains. Our concept is heavily reliant on mobile technology, particularly remote physiological monitoring using Bluetooth. Respiratory events are gathered, and eight-channel EEG readings are captured from the frontal, central, and parietal (Fpz-Cz, Pz-Oz) regions. EEGs are preprocessed with a Butterworth bandpass filter, and features are subsequently extracted from the filtered EEG signals by employing the wavelet-packet-transform (WPT) method to categorize the signals into four frequency bands: α, β, θ, and δ. A mutual information (MI) technique selects the most descriptive features for further classification. The reduction in the number of prominent features improves the sleep-onset classification speed in the support vector machine (SVM) and results in a high sleep-onset recognition rate. Test results reveal that the combined use of the EEG and respiration signals results in 98.6% recognition accuracy. Our proposed application explores the possibility of processing long-term multi-channel signals.