Jesús García-Guzmán

Parametric model of a polymeric chemoresistor for use in smart sensor design and simulation

Abstract A novel parametric model of a polymeric chemoresistor is proposed for application in the design and simulation of smart gas sensors. The model has been implemented using Cadence™ software and enables the simulation of both the static and dynamic response of a chemoresistor to a mixture of different gases. It also takes into account parametrically the effects of ambient temperature, humidity and sensor noise. The layout design and a schematic symbol have also been generated in Cadence -thus creating a resistive polymeric cell that can be used in the general design of smart ASIC based systems. The top cell comprises several sub-cells allowing versatility and adaptability in implementation through its modular structure. By changing the values of the simulation parameters and/or the mathematical model of the sub-cell that evaluates the gas sensor response, it is possible to extend its application to the design and simulation of chemoresistors in different configurations and with different gas sensitive materials. Here we illustrate our model in the design and simulation of resistive sensors employing carbon-black polymer composite films as the class of gas sensitive material.

Design and simulation of a smart ratiometric ASIC chip for VOC monitoring

This paper reports on the design and simulation of a novel ratiometric application specific integrated circuit (ASIC) chip for the monitoring of volatile organic compounds (VOCs) or gases. The design integrates two polymeric chemoresistors in a ratiometric configuration, together with smart circuitry, into a single chip fabricated through a standard silicon CMOS process. The circuit provides automatic compensation of signal from variations in both supply voltage and ambient temperature. On-chip control of the operating temperature of the sensors is also an option. The response of the ratiometric set of polymeric chemoresistors to different concentrations of gases at different temperatures and humidities was simulated with the aid of a novel parametric Cadence model. Simulations confirm that the ratiometric configuration is less sensitive to temperature variations and that it also has a better performance in terms of humidity dependence when compared to an individual chemoresistor. These features, together with its ability to compensate for a large range in values of polymer resistance, make us believe that the circuit offers relevant smart capabilities at a very low-cost and so it can be used as the main component for the mass production of a self-calibrating, programmable, palm-top instrument.

A wireless activity monitoring system for monkey behavioural study

A Wireless Sensor Network (WSN) for monitoring of animal behaviours has been proposed. Preliminary results are presented here in order to demonstrate the potential of the system, which is aimed to investigate wild life of two species of monkeys in their natural habitat in the Mexican jungle. The novel platform comprises sensing nodes capable of measuring and recording the position, posture and activity level of animals. Each node is provided with wireless communication capabilities and the network topology includes a base station connected to a personal computer, in which the graphical user interface (GUI) and the proposed algorithm allow the visualization and processing of the collected data. Special care is giving to power-saving issues by applying power-aware techniques aimed to prolong the lifespan of the deployed sensors and devices. Results show high consistency and accuracy in the system response, with data being transmitted and recorded efficiently. Further improvements are envisaged and proposed for the intelligent monitoring system.

A wireless body area network for pervasive health monitoring within smart environments

A wireless wearable health monitoring system that is capable of tracking various vital signs and trigger emergency aid when abnormalities are detected, is proposed. The strength of the system lies in its distributed nature of operating either in standalone mode or integrating into a smart environment platform. A description of a basic version of the system is presented, together with preliminary results obtained from the experimental set-up. It is demonstrated that the developed body area network performs as expected for simple monitoring such as fall detection and for correlation of activity levels with other medical information to reduce false triggering of alarms.

Smart ASIC chip for vapor detection based upon carbon black/polymer composite nanomaterials

In this paper we report on the characterisation of a smart ASIC chip comprising a pair of room temperature resistive vapour sensors in a ratiometric configuration. This novel design enables the near elimination of several undesirable baseline effects and provides an automatic offset of the output signal. The novel ASIC chip has been designed and fabricated through a standard 0.7 μm CMOS process. The ASIC response has been modelled prior to fabrication as reported elsewhere. There are two main stages in the circuit: one for the processing and conditioning of the sensor signals and the other for temperature control. Two sets of sensor electrodes are positioned in two opposite corners of the chip and are connected in a non-inverting operational amplifier configuration. Carbon black/polymer composite materials have been deposited across the electrodes to create the sensing chemoresistors and illustrate the functionality of the chip. Sample devices were created by depositing either the same nanomaterial on both electrodes and having one active and one passive sensor, or by depositing two different materials, thus creating two active sensors. Following deposition, the responses of the ASIC devices to toluene and ethanol vapours in air have been characterised in an automated mass flow system and presented here.

FPGA implementation of a smart home lighting control system

Intelligent homes are nowadays equipped with all sort of smart devices for the control of appliances and domotic applications. One of the main aims of these devices is, apart from the comfort of having automated systems, the efficient use of energy. This paper reports on the design and FPGA implementation of a smart lighting system for application in small smart homes. Unlike those systems using pervasive remote controls, the proposed system is based on automatic detection of application conditions, and it requires minimum programming by the end user.

Design and simulation of a three-phase generator for use with smart systems in medical microinstrumentation

In this paper, we report on the design of a digital three-phase micro-generator of voltage that is going to be part of a lab-on-chip system based on smart sensors for medical diagnosis and instrumentation. The digital generator is implemented on a field-programmable gate array (FPGA) and it will deliver three voltage waveforms with equal magnitudes and phase shifted 120° one of each other. The benefits of this power source are mainly related to the ability of balanced three phase systems to deliver constant instantaneous power to the loads, thus eliminating vibrations and other disturbances produced by oscillation in the output waveforms of typical mono phase systems. It is expected that the resulting three phase digital generator will serve as a very reliable power source for driving micromechanical actuators used in sophisticated medical applications.

Remote Laboratories for Teaching and Training in Engineering

Typical mechatronic systems are a combination of advanced technologies involving several disciplines. This multidisciplinary approach to the development of industrial applications provides great opportunities for the implementation of e-learning environments and collaborative schemes. Engineering education, in particular, benefits from many of these advances, among which, virtual instrumentation is a useful tool for the development of virtual environments, e-learning spaces and, particularly, remote laboratories. This chapter describes the implementation of web-based laboratories that allow the remote operation of experiments used as training exercises in undergraduate engineering courses. The remote laboratories were developed using LabVIEW software, and they enable remote control and monitoring of laboratory equipment, allowing engineering students to perform experiments in real time, at their own pace, from anywhere, and whenever is suitable for them. Besides the experimental training that the web-based laboratories provide to students, the system is also a powerful teaching tool since real-time demonstrations of the experiments can be performed, and they also can be simultaneously monitored by a group of students. This approach is highly beneficial for engineering schools in developing countries, as resources can be shared through the Internet. A description of the system and three proposed experiments is presented, together with the experimental results.

Comparative Analysis of Optoelectronic Properties of Glucose for Non-invasive Monitoring

Among the diversity of methods for glucose level monitoring in human blood, invasive techniques are still the most commonly used. Blood samples, usually obtained with finger-pricking devices, are analysed through enzymatic reactions via electrochemical or photometric principles. In this paper, non-invasive methods for blood glucose monitoring are studied and compared, while also analysing optical and electronic properties of glucose. From this comparative analysis, proposals are made towards the design and characterisation of novel devices capable of monitoring blood-glucose levels through optoelectronic non-invasive procedures. Alteration of electrical parameters of cellular membrane, such as electric permittivity and conductivity as a function of blood glucose concentration, are observed and compared to the responses to optical stimuli. The investigation is developed by establishing a correlation between the effects of diffusion and dispersion of light on the concentration and dispersity of blood particles, and the response of electrical parameters under different glucose concentrations. As a result of the analysis, recommendations are made for the most suitable parameters and instrumental methodology, in terms of feasibility, easiness and precision, for non-invasive monitoring of blood glucose levels.

Embedded microcontroller system for piecewise-linear laser projection

This paper describes a first approach of a microcontroller system specifically dedicated to implement the socalled piecewise-linear method for laser projection. An embedded system based on the Atmel AVR microcontroller is designed to control a dual-axis galvo motor/mirror assembly in accordance with the evaluation of a couple of one-dimensional piecewise-linear functions. Such functions are derived from a parametric decomposition of the curve to be sketched by laser projection. By this hardware realization, the well-known advantages (less memory consumption and sharpness of projected figures) of the piecewise-linear method over the commercial point-based, standard can be verified.