Centre for Nanotechnology

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Browsing Centre for Nanotechnology by Subject "Biosensor"

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    Fabrication of Polyaniline-Based Nano Materials for the Application in Energy Harvesting and Sensing Devices
    (2020) Palsaniya, Shatrudhan
    PANI nanomaterials strongly depend on the distribution of nanofillers for property enhancement. Based upon these nanomaterials, a brief introduction of energy storage and sensing devices have been included in Chapter-1. Chapter-2 describes binary and ternary nanocomposites of PANI, G and MoS2. Among them, PANI-G-MoS2 ternary nanocomposite exhibits excellent electrochemical activity and enhanced cyclic stability. Chapter-3 describes GO, RGO, and α‒MnO2 based PANI functionalized binary and ternary nanocomposites. Herein, PANI-RGO-MnO2 has appeared an excellent candidate for high‒density energy storage material with superior dielectric strength. Chapter-4 presents a comparative study of binary and ternary nanocomposites of PA6, rGO, and PANI components. We have observed that PA6-rGO-PANI 1:2 shows an excellent electrochemical performance with improved cyclic stability, as compared to other composites. Further, fabricated symmetric supercapacitor devices also have demonstrated outstanding performance. Chapter 5 unveils ZnO (transition metal oxide), and RGO based PANI functionalized nanocomposites. In particular, PANI-RGO-ZnO 2:1 composite reveals a superior performance as an electrode material. Chapter-6 describes preparation of PANI-ES and PANI-EB thin film, deposited on glass and n-type Si wafer substrates using a vacuum evaporation technique. We have observed that deposition of PANI-EB is relatively easier than PANI-ES. Contrary to PANI-EB, PANI-ES thin-film shows better electrical conductivity. Hence, fabricated thin-film capacitors also have shown remarkable current density and energy density with the high percolation threshold. Chapter-7 presents a hierarchical mesostructure of PANI nanorods by incorporating SDS and F127 as structure-directing agents (SDAs). The PANI-SDS-F127 1:1 composition has shown higher glucose sensitivity with a lower detection limit, attributed to the synergistic effect of available organic components. Chapter 8 summarizes the thesis work, with an outlook for future study.
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    SiO2 Trench Embedded Field Effect Transistor for Biosensing Applications
    (2022) Naorem, Monica
    Bio-FETs couple a transistor device with a bio-sensitive layer that can specifically detect bio-molecules. There are many challenges involved in a Bio-FET such as the selection of a suitable substrate and channel material, provision of a sensing film layer on the active site of FET, setting up a receptor on the sensing film layer to enable ion detection, the inclusion of liquid holding facility, etc. Moreover, rapid response and higher sensitivity are required for the sensor. The proposed structure has a SiO2 trench along with a reservoir that removes the need for any extra mold for containing the analyte liquid. The inbuilt trench structure brings additional benefits such as ease in the analyte pouring during the sensing, helps in the storage of liquid, minimizes the overflow of the analyte liquid and improves gate control by an increment in effective oxide capacitance. The device was fabricated using photolithography followed by etching steps. A basic trench embedded FET device was electrically characterized with KCl as an ionic liquid channel. Using the fabricated device, H2O2 was sensed using GO/PPy nanocomposites as the channel, and glucose & LDH were sensed using GO/Ag NPs. This FET device can detect the occurrence of a chemical reaction in real-time.
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    Surface acoustic wave based biosensor for the detection of hepatitis B surface antigen
    (2019) Goswami, Namami
    The thesis presents a Surface Acoustic Wave (SAW) based dual delay line immuno-biosensor for successful in vitro detection of Hepatitis B Surface Antigen (HBsAg) in human serum. HBsAg is the first biomarker to appear in the blood of an infected patient. The immuno-biosensor system includes interdigitated transducer (IDT) electrodes wherein area between the transmitting and receiving interdigitated transducer (IDT) is functionalized by a linker. To achieve highly specific detection, Anti-HBsAg antibody is bound to the linker to capture HBsAg in the sample. PBS was used as the negative control in the reference delay line. Thus, the effect of common factors like noise and humidity on the output characteristic of the system is advantageously avoided. Samples of HBsAg of varying concentrations are used for measurements, whereby detection of HBsAg in the sample is confirmed by the change in S21 parameter of the system in real time whenever the antigen-antibody reaction took place on the system platform.
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    Surface acoustic wave devices using coupled resonance with nano- and microstructures for biosensing applications
    (2018) Trivedi, Shyam
    Surface acoustic wave (SAW) is an elastic wave that propagates on the surface of a material with its energy mainly confined to a depth of about one wavelength at the surface. Usually, SAW devices are realized on polished piezoelectric substrates with metallic interdigital transducer (IDT) made on the surface for the transduction of electrical energy to acoustic energy and vice versa. In the last few years, the demand for low cost, compact and sensitive biosensors for the detection of disease-causing pathogens has increased. SAW biosensor is an analytical device that comprises IDT on a piezoelectric substrate as transducer and a chemically functionalized active area that electivity detects a specific biological analyte. SAW biosensors are helpful because they offer real-time, label-free detection with high sensitivity and selectivity. They are a promising low-cost alternative to the conventional fluoroimmunoassay, radioimmunoassay and surface plasmon based optical biosensing techniques. Of all the SAW-based biosensing systems, Love wave (LW) devices are the most promising choice for biosensor design. Guiding layer of the LW devices keeps the energy of the wave at the surface providing high mass sensitivity and also shields the IDT from liquids. Finite element (FE) simulation of LW device considering different guiding layer materials to calculate mass sensitivity, insertion loss and the coupling coefficient of the device are presented in the thesis.