This document discusses nanosensors and their roles and applications in nanoelectronics. It describes how nanosensors can convey information about nanoparticles and have various medical and other uses. Some key applications of nanosensors discussed are in computers to make processors more powerful, in energy production to create more efficient solar cells, and in medical diagnostics to detect biomolecules in real time. Nanosensors are also discussed as having potential uses in chemical sensing by detecting various gas molecules and in detecting single molecules using nano-cantilevers. The document outlines several approaches for producing nanosensors, including top-down lithography, bottom-up assembly of individual atoms/molecules, and self-assembly of starter molecules.

1. Sensors and
Instrumentation
Digital Assignment
Topic:
Nanoelectronics
– Role of nanosensors
By:
Rishu Mishra
15BEC0187 - (TA1)

2. - Role of nanosensors
Introduction:
Nanoelectronics refer to the use of nanotechnology in electronic components.
The term covers a diverse set of devices and materials, with the common characteristic
that they are so small that inter-atomic interactions and quantum mechanical properties
need to be studied extensively. Some of these candidates include: hybrid
molecular/semiconductor electronics, one-dimensional nanotubes/nanowires, or
advanced molecular electronics.
Nanosensors are any biological, chemical, or surgical sensory points used to
convey information about nanoparticles to the macroscopic world. Their use mainly
includes various medicinal purposes and as gateways to building other Nano products,
such as computer chips that work at the nanoscale and Nano robots. There are several
ways being proposed today to make nanosensors
Nanoelectronics increase the capabilities of electronic devices such as improving
the display screens on electronics devices by decreasing the weight and thickness of
the screens and reducing the consumption of power
There are many approaches to Nano electronics. Few of them includes, Nanofabrication
which involves transistor operation based on a single electron. Molecular electronics, in
which a molecular level diode / transistor might be synthesized by organic chemistry.
Nanoionics, which deals with the transport of ions and Nano photonics, deals with the
behavior of light on the nanoscale.
Nanosensors, convey information about nanoparticles. Many scientific breakthroughs
in Nanotechnology has been contributed by Nanosensors. Different types of sensors
are built from nanomaterials to detect chemical vapors, to detect range of chemical
vapors, to sense bacteria or viruses, to detect single molecules, to help pharmaceutical
companies in production of drugs.
The Uses of Nanosensors:
Scientists and engineers are collaborating across disciplines to develop and
network miniaturized intelligent nanosensors that can rapidly and remotely detect
change in their surroundings. These sensors have a wide range of potential
applications: environmental, medical, military and transportation.

3. Current high-technology production processes are based on traditional top down
strategies, where nanotechnology has already been introduced silently. The critical
length scale of integrated circuits is already at the nanoscale (50 nm and below)
regarding the gate length of transistors in CPUs or DRAM devices.
1. Computers:
Nanoelectronics holds the promise of making computer processors more
powerful than are possible with conventional semiconductor fabrication
techniques. A number of approaches are currently being researched, including
new forms of nanolithography, as well as the use of nanomaterials such as
nanowires or small molecules in place of traditional CMOS components. Field
effect transistors have been made using both semiconducting carbon nanotubes
and with heterostructured semiconductor nanowires.
Attaching a single particle onto the end of a carbon nanotube and
measuring the vibrational frequency of the nanotube both with and without the
particle. The discrepancy between the two frequencies also allowed the
researchers to measure the mass of the attached particle.
 projected products most commonly involve using nanosensors to build
smaller integrated circuits, as well as incorporating them into various other
commodities made using other forms of nanotechnology for use in a variety of
situations including transportation, communication, improvements in structural
integrity, and robotics.
2. Energy Production:
Research is ongoing to use nanowires and other nanostructured materials
with the hope to create cheaper and more efficient solar cells than are possible
with conventional planar silicon solar cells. It is believed that the invention of
more efficient solar energy would have a great effect on satisfying global energy
needs.
The average person's body could, theoretically, generate 100 watts of
electricity (about 2000 food calories per day) using a Bio-Nano generator.
However, this estimate is only true if all food was converted to electricity, and the
human body needs some energy consistently, so possible power generated is
likely much lower. The electricity generated by such a device could power
devices embedded in the body (such as pacemakers), or sugar-fed Nano robots.
Much of the research done on Bio-Nano generators is still experimental, with
Panasonic's Nanotechnology Research Laboratory among those at the forefront.
3. Medical Diagnostics:

4. There is great interest in constructing Nano electronic devices that could
detect the concentrations of biomolecules in real time for use as medical
diagnostics, thus falling into the category of Nano medicine. A parallel line of
research seeks to create Nano electronic devices which could interact with single
cells for use in basic biological research. These devices are called nanosensors.
Such miniaturization on Nano electronics towards in vivo proteomic sensing
should enable new approaches for health monitoring, surveillance, and defense
technology.
 Medicinal uses of nanosensors mainly revolve around the potential of
nanosensors to accurately identify particular cells or places in the body in
need. By measuring changes in volume, concentration, displacement and
velocity, gravitational, electrical, and magnetic forces, pressure, or
temperature of cells in a body, nanosensors may be able to distinguish
between and recognize certain cells, most notably those of cancer, at the
molecular level in order to deliver medicine or monitor development to specific
places in the body
 One example of nanosensors involves using the fluorescence properties of
cadmium selenide quantum dots as sensors to uncover tumors within the
body. By injecting a body with these quantum dots, a doctor could see where
a tumor or cancer cell was by finding the injected quantum dots, an easy
process because of their fluorescence. Developed Nano sensor quantum dots
would be specifically constructed to find only the particular cell for which the
body was at risk. A downside to the cadmium selenide dots, however, is that
they are highly toxic to the body.
 Another use of nanoparticles is in the detection of volatile organic compounds
(VOCs). Researchers have found that by embedding metal nanoparticles
made of substances such as gold in a polymer film, you create a VOC Nano
sensor.
4. Chemical sensors:
They too, have been built using nanotubes to detect various
properties of gaseous molecules. Carbon nanotubes have been used to
sense ionization of gaseous molecules while nanotubes made out of
titanium have been employed to detect atmospheric concentrations of
hydrogen at the molecular level. Many of these involve a system by which
nanosensors are built to have a specific pocket for another molecule.
When that particular molecule, and only that specific molecule, fits into the
Nano sensor, and light is shone upon the Nano sensor, it will reflect
different wavelengths of light and, thus, be a different color in a similar
fashion, Flood et al. have shown that supramolecular host-guest chemistry
offers quantitative sensing using Raman scattered light as well as SERS.

5. 5. Sensors using semiconductor nanowire detection elements:
These sensors are capable of detecting a range of chemical
vapors. When molecules bond to nanowires made from semiconducting
materials such as zinc oxide, the conductance of the wire changes. The
amount that the conductance changes and in which direction depends on
the molecule bonded to the nanowire.
For example, nitrogen dioxide gas reduces how much current the wire
conducts, and carbon monoxide increases the conductivity. Researchers
can calibrate a sensor to determine which chemical is present in the air by
measuring how the current changes when a voltage is applied across the
nanowire.
6. Nano cantilevers:
These devices are being used to
develop sensors that can detect single
molecules. These sensors take advantage
of the fact that the Nano cantilever
oscillates at a resonance frequency that
changes if a molecule lands on the
cantilever, changing its weight. Coating a
cantilever with molecules, such as
antibodies, that bond to a particular
bacteria or virus determines what bacteria or
virus will bond to the cantilever.
Production Methods:
1. There are currently several hypothesized ways to produce nanosensors. Top-down
lithography is the manner in which most integrated circuits are now made. It involves
starting out with a larger block of some material and carving out the desired form.
These carved out devices, notably put to use in specific microelectromechanical
systems used as micro sensors, generally only reach the micro size, but the most
recent of these have begun to incorporate Nano sized components.
2. Another way to produce nanosensors is through the bottom-up method, which
involves assembling the sensors out of even more minuscule components, most
likely individual atoms or molecules. This would involve moving atoms of a particular
substance one by one into particular positions which, though it has been achieved in
laboratory tests using tools such as atomic force microscopes, is still a significant
difficulty, especially to do en masse, both for logistic reasons as well as economic
ones. Most likely, this process would be used mainly for building starter molecules
for self-assembling sensors.
Figure 1.Credit: Courtesy of R. Bashir
and M. A. Alam of Purdue University;
image drawn by Seyet, LLC

6. (A) An example of a DNA molecule used as a starter for larger self-assembly.
(B) An atomic force microscope image of a self-assembled DNA Nano grid.
Individual DNA tiles self-assemble into a highly ordered periodic two-dimensional DNA
Nano grid.
3. The third way, which promises far faster results, involves self-assembly, or “growing”
particular nanostructures to be used as sensors. This most often entails one of two
types of assembly. The first involves using a piece of some previously created or
naturally formed nanostructure and immersing it in free atoms of its own kind. After a
given period, the structure, having an irregular surface that would make it prone to
attracting more molecules as a continuation of its current pattern, would capture
some of the free atoms and continue to form more of itself to make larger
components of nanosensors.
Economic Impacts:
First, however, Nano sensor developers must overcome the present high costs of
production in order to become worthwhile for implementation in consumer products.
Additionally, Nano sensor reliability is not yet suitable for widespread use, and, because
of their scarcity, nanosensors have yet to be marketed and implemented outside of
research facilities. Consequently, nanosensors have yet to be made compatible with
most consumer technologies for which they have been projected to eventually enhance.
Social Impacts:
The advancement in detecting and sensing different biological and chemical
species with increased capacity and accuracy may transform societal mechanisms that
were originally designed on uncertainty and imprecise information.
For example, the ability to measure extremely low amounts of air pollutants or
toxic materials in water raises questions and dilemmas of risk thresholds especially if
the advancement of such technologies outpaces the ability of the public to respond. As
another example, medical sensors will not only help in diagnoses and treatment but
may also predict the future profile of an individual. This will add to the information used
by health insurance companies to grant or deny coverage. Other social issues resulting
from the widespread use of nanosensors and surveillance devices include privacy
invasion and security issues.