Incorporation of magnetic microparticles (~ 1 um) at electrode structures increases electron transfer e¢ ciency, observed as increased current, for multiple electrochemical systems. Current increases occur with magnetic field. Inclusion of magnetic materials into the cathode matrix of alkaline MnO2 batteries requires the materials to be stable in the strong base electrolyte, typically 6 to 9 M KOH. Samarium cobalt magnetic particles sustain strong permanent magnetic fields and are stable in base without surface modification. Studies were undertaken at fast (C/2), moderate (C/3), and slow (C/5) constant current discharges. Here, alkaline MnO2 batteries generated increased power and energy when magnetic microparticles are incorporated into the cathode of the battery. Because of anode limitations in the battery, total coulombic output is not increased for the first electron discharge, but the available power and energy is significantly higher compared to nonmagnetic batteries at voltages above 0.9V. Constant current discharge curves of magnetic batteries demonstrate higher voltages than nonmagnetic batteries at a given time, which translates to greater power output. This effect is also observed by electrochemical impedance spectroscopy, where charge transfer resistance is less for magnetically modified cells. This work also developed voltammetric measurement protocols for acetone concentration collected in the liquid and vapor phase and measured in solution. Acetone on the breath is an indicator for physiological dysregulation. Measurements are demonstrated for acetone concentrations across the human physiological range, 1 uM to 10 mM at platinum electrodes in 0.5 M H2SO4. Effects arise through adsorption of acetone from the gas phase onto a platinum surface and hydrogen in acidic solution within the voltammetric butterfly region. The protocol is demonstrated to yield breath acetone concentration on a human subject within the physiological range and consistent with ketone urine test strip.

In this work, we performed an experimental analysis using a two-dimensional semiconducting transition metal dichalcogenide (TMD), specifically tungsten diselenide (WSe2), for gas sensor applications. Our method entailed building a chemically liquid exfoliated WSe2 gas sensing device with gold (Au) electrodes to measure its reaction and sensitivity to environmental gasses such as CO2 and N2. The 2D thin film was created through a solution processing method and electrically coupled in a two-terminal configuration; photonic curing system along with the hot plate annealing process was used on the thin film for rapid annealing, enhancing particle connectivity, stable crystal structure, and increasing overall electrical conductivity. The inkjet printing technology is used to explore the potential of the 2D thin film fabrication process that defines a well-controlled and scalable additive manufacturing process at the nano level that makes it possible to develop next-generation flexible devices. The additive nano-manufacturing process allowed us to establish the film's structure and chemical properties before measuring the electrical characteristics of the films when exposed to CO2 and N2 gases at room temperature. To explore and validate the sensitivity to human interaction with the gas-sensing device, we carried out further experiments with direct exposure to human breath in an open environmental space which shows a promising landmark for developing a next-generation flexible breath-sensing device.

The growth of sensors and sensing technologies have made significant impact in our day-to-day life. The five principle sensory organs of our body should perform effectively, so that we can lead a good healthy life. Apart from these natural sensors, there are man-made sensors that helps us to cope with diseases, organ failure etc. and enable us to lead a normal life. In recent years, with the prevalence of new kind of diseases, the need for new type of biomedical sensors is becoming very important. As a result, sensors used for biomedical applications have become an emerging technology and rapidly growing field of research. The aim of the present thesis work is to use the piezoelectric property of Polyvinylidene Fluoride (PVDF) film for the development of biomedical sensor and studying its application for human respiration/breathing related abnormalities. PVDF nasal sensor was designed in cantilever configuration and detailed theoretical analysis of the same was performed. Based on theoretical and experimental results, the PVDF nasal sensor dimensions were optimized. Suitable signal conditioning circuitry was designed and a measurement system for biomedical application was developed. The developed PVDF nasal sensor was calibrated using MEMS low-pressure sensor. The PVDF nasal sensor system has been applied in different biomedical applications namely, (i) to monitor human respiration pattern, (ii) to identify different Respiration Rates (RR), (iii) to evaluate Deviated Nasal Septum (DNS) in comparison with other objective method and, (vi) to clinically investigate nasal obstruction in comparison with subjective method. The thesis is divided into seven chapters. Chapter 1 This chapter gives a general introduction about biomedical sensors, piezoelectric sensing principle and PVDF polymer films along with the relevant literature survey. The brief introduction as well as literature survey of techniques used to monitor human respiration and to measure nasal obstruction is also included in this chapter. Chapter 2 This chapter gives details about the design of the PVDF nasal sensor in the cantilever configuration for sensing nasal airflow along with the relevant theoretical equations. Also, the details on the optimization of the PVDF nasal sensor dimensions based on the theoretical and experimental analysis are presented. Chapter 3 This chapter reports the designing of the necessary signal conditioning hardware along with the data acquisition unit for the PVDF nasal sensor. The signal conditioning hardware unit made consists of charge amplifier, low-pass filter and an amplifier. Besides, a complete measurement system for biomedical application was developed using PVDF nasal sensor and its merits and demerits were discussed. Chapter 4 In this chapter, an experimental set-up for measuring human respiration/breathing pressure using water U-tube manometer has been described. Also, the calibration procedure followed for the developed PVDF nasal sensor using a Micro Electro Mechanical Systems(MEMS) low pressure sensor is reported. Apart from these, the details on the measurement of deflection of the PVDF cantilever sensing element using laser displacement setup are provided. In addition, the PVDF nasal sensor was also calibrated for various air flow rates. At the end, a study has been reported on optimizing the position the PVDF nasal sensor with respect to human nose. Chapter 5 This chapter is divided into two sections, Section 5.1: This section describes the applicability of the PVDF nasal sensor using its piezoelectric property to monitor the human respiration pattern of each nostril simultaneously. The results of the PVDF nasal sensor have also been evaluated by comparing with Respiratory Inductive Plethysmograph(RIP) technique in normal subjects. Section 5.2: In this section, PVDF nasal sensor, RIP and Nasal Prongs (NP) techniques were used to measure the RR of healthy adults. The aim here was to evaluate the presently developed PVDF nasal sensor for identifying different RR compared to „Gold standard‟ RIP and NP methods. Chapter 6 This chapter is divided into two sections. Section 6.1: This section reports about the utilization of the developed PVDF nasal sensor for clinical application on the patient population. For this purpose, the performance of the PVDF nasal sensor measurements has been compared with the Peak Nasal Inspiratory Flow(PNIF) objective technique and visual analog scale (VAS). Section 6.2: This section describes about the use of PVDF nasal sensor system to measure nasal obstruction caused due to DNS objectively. Further, the results of the PVDF nasal sensor were compared with subjective techniques namely, VAS and clinician scale in patients and control group. Chapter 7 This chapter is composed of two sections. Section 7.1: This section summarizes the salient features of the work presented in this thesis. Section 7.2: This section reports a scope for carrying out further work.