2019). In their work, Yaqoob et al. reported simple chemical synthesis of foldable
nanosensor by using rGO assisted MWCNTs-supported Pd nanocubes and used the
nanosensor for hydrogen detection (Yakoob et al. 2015). Pd can be incorporated to
micro- or nanostructures of other metals or semiconducting MOX to improve their
gas sensing and optical properties. For e.g., Yi et al. reported Pd NPs decorated
nanogold wires (Pd/NPG) and used them for nanobiosensors for highly sensitive
detection of traced dopamine (DA) with a low LOD of 1 μM, and 1–220 μM broad
detection range (Yi et al. 2017).
5.3.2.6 Nanosensor Fabrication with Electrospun Nanofibers
Fabrication of nanofibers (NFs) is economical, and these have properties like high
efficiency, low sample requirement, multifunctionality, direct detection of analyte,
high stability, less power consumption and low LOD (Veisi 2013; Asmatulu and
Khan 2019). These properties of NFs arise due to their flexibility, small dimensions,
tunable conduction properties, and higher specific surface area, making them useful
for integration into sensing elements, and other industrial applications. Further, the
dimensions and surface functionalities of NFs can be tailored to enhance absorption
and diffusion rates for rapid response and signal transfer for better sensitivity, labelfree sensing and dynamic behaviour (Veisi et al. 2013; Veisi 2013; Asmatulu and
Khan 2019). Electrospinning is a useful technique for nonwoven and woven, micronanoscale fibres production. The NFs produced by this method have smaller
diameters leading to high porosity, more surface functionality, greater permeability,
and better mechanical strength, resulting in making them suitable materials for
nanosensors applications. Basic setup of electrospinning is shown in Fig. 5.5.
Various types of Micro- and nanoscale fibres for application as nano- and biosensors
can be produced by adjusting parameters like flow rate, concentration of polymer,
screen and capillary distance, electrical potential, temperature, air velocity and
humidity (Asmatulu and Khan 2019).
Ding et al. discussed the most extensive application of electrospun NFs for
medical purposes. It was also reported that due to porous and flexible nature along
with high specific surface area, NFs can be used for designing ultrasensitive
nanosensors for different industries. Recent progress in sensing approaches (optical,
photoelectric, impedance etc.,) were also summarized in their work (Ding et al.
2010).
Wang et al., have also discussed the recent development of electrospun nanofiberbased nanosensors, and their application for detection of different hazardous
analytes (Wang et al. 2014).
5.3.2.7 Quantum Dots (QDs)
QDs are nanocrystals with semiconductor nature. These have typical MX composition where, M is commonly Zn or Cd and X is Se, S or Te (Willner and Vikesland
2018). As discussed above, QDs can act as outstanding optical transducers due to
broad absorption bands and narrow fluorescence emission bands. Emission bands of
QDs can be tuned by variation in their composition, size and shape. Often, a shell or
a second MX alloy is coated on QDs to generate highly tuneable core/shell QDs.
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nanosensor by using rGO assisted MWCNTs-supported Pd nanocubes and used the
nanosensor for hydrogen detection (Yakoob et al. 2015). Pd can be incorporated to
micro- or nanostructures of other metals or semiconducting MOX to improve their
gas sensing and optical properties. For e.g., Yi et al. reported Pd NPs decorated
nanogold wires (Pd/NPG) and used them for nanobiosensors for highly sensitive
detection of traced dopamine (DA) with a low LOD of 1 μM, and 1–220 μM broad
detection range (Yi et al. 2017).
5.3.2.6 Nanosensor Fabrication with Electrospun Nanofibers
Fabrication of nanofibers (NFs) is economical, and these have properties like high
efficiency, low sample requirement, multifunctionality, direct detection of analyte,
high stability, less power consumption and low LOD (Veisi 2013; Asmatulu and
Khan 2019). These properties of NFs arise due to their flexibility, small dimensions,
tunable conduction properties, and higher specific surface area, making them useful
for integration into sensing elements, and other industrial applications. Further, the
dimensions and surface functionalities of NFs can be tailored to enhance absorption
and diffusion rates for rapid response and signal transfer for better sensitivity, labelfree sensing and dynamic behaviour (Veisi et al. 2013; Veisi 2013; Asmatulu and
Khan 2019). Electrospinning is a useful technique for nonwoven and woven, micronanoscale fibres production. The NFs produced by this method have smaller
diameters leading to high porosity, more surface functionality, greater permeability,
and better mechanical strength, resulting in making them suitable materials for
nanosensors applications. Basic setup of electrospinning is shown in Fig. 5.5.
Various types of Micro- and nanoscale fibres for application as nano- and biosensors
can be produced by adjusting parameters like flow rate, concentration of polymer,
screen and capillary distance, electrical potential, temperature, air velocity and
humidity (Asmatulu and Khan 2019).
Ding et al. discussed the most extensive application of electrospun NFs for
medical purposes. It was also reported that due to porous and flexible nature along
with high specific surface area, NFs can be used for designing ultrasensitive
nanosensors for different industries. Recent progress in sensing approaches (optical,
photoelectric, impedance etc.,) were also summarized in their work (Ding et al.
2010).
Wang et al., have also discussed the recent development of electrospun nanofiberbased nanosensors, and their application for detection of different hazardous
analytes (Wang et al. 2014).
5.3.2.7 Quantum Dots (QDs)
QDs are nanocrystals with semiconductor nature. These have typical MX composition where, M is commonly Zn or Cd and X is Se, S or Te (Willner and Vikesland
2018). As discussed above, QDs can act as outstanding optical transducers due to
broad absorption bands and narrow fluorescence emission bands. Emission bands of
QDs can be tuned by variation in their composition, size and shape. Often, a shell or
a second MX alloy is coated on QDs to generate highly tuneable core/shell QDs.
114
U. Chakraborty et al.