A microscopically small technology making a big impact

Ahsen Khan
6 min readMar 8, 2020

Nanosensors are a good example of a useful nanotechnology. It is already being used in important fields such as medicine, water distribution, agriculture, the food industry, the military, and more. Nanosensors are tiny sensors which are able to measure temperature at the nanoscale (for example, the temperature of individual cells), detect the presence of certain substances or bacteria, and measure tiny amounts of electromagnetic radiation. Nanosensors are usually sensors with at least one of their dimensions around 100 nanometers. In comparison, a human hair is usually between 50,000 and 100,000 nanometres thick. Nanosensors are not necessarily microscopic, but they observe something that is at the nanoscale.

Why they’re important

Nanosensors can detect much smaller changes and can detect particles and temperature changes that other technologies cannot. They can measure things at the scale of individual cells and even molecules.

A picture of a nanosensor
An example of a nanosensor
  • Nanosensors can detect much smaller changes
  • Nanosensors have less impact on the thing being measured
  • They are faster to detect things.
  • They are much smaller and can fit into smaller spaces and/or get closer to the subject for higher accuracy.
  • Low power consumption due to their small size

Applications of nanosensors

There are a lot of different nanosensors which can do different things under different conditions. Although it may seem unlikely, there are a lot of applications for nanosensors in various different fields.

  • Nanosensors are being developed to detect early signs of cancer and many of them have already been quite successful
  • Nanosensors can be used in water treatment facilities to monitor the quality of their water in real time
  • Nanosensors can be used to monitor nutrient quality and moisture of soil for plants in agriculture
  • They can also evaluate the quality of food
  • Nanosensors can be used by security at airports to detect explosives or toxic chemicals
  • Nanosensors in hospitals could be used to check for bacteria and contamination

As you can see here, nanosensors are already being used in surprisingly important places which you might not have expected, such as cancer detection and security.

A possible application to current problems

In researching nanotechnology, I realized that nanosensors could also be used to detect COVID-19 quickly. This could be applied to public spaces, to be able to check where it is necessary to clean, and also could be used at airports and borders to quickly check if anyone has the virus. This could speed up the process for doctors to check patients for COVID-19, and could even be affordable enough for people to check at home so that they know if they need to go to the hospital. Either a carbon nanotube nanosensor or a nanocantilever could work for this application.

How they work

There are a few different types of nanosensors which work in slightly different ways.

  • One type of nanosensor uses semiconductor nanowires. When a certain molecule of a substance bonds to it, its conductivity changes, which can be measured. The change in conductivity depends on the substance bonding to the nanowire. If for example, nitrogen dioxide gas lands on the sensor, the conductivity is decreased, whereas if carbon monoxide lands on the sensor, the conductivity in increased. This way, nanosensors can be calibrated to identify individual molecules of substances in the air for example.
2 Carbon Nanotubes On A Human Hair
2 Carbon Nanotubes on a Human Hair
  • Another type of nanosensor uses carbon nanotubes. Similar to above, their conductivity changes depending on the molecule that bonds to it, which can be measured.
  • This type of carbon nanotube sensor can also be used to detect bacteria and viruses. An antibody is attached to the nanotube, and when the corresponding bacteria or virus bonds to the nanotube, the conductivity changes and can be measured. Scientists believe this could be very effective for detecting bacteria in hospital environments.
  • Nanocantilevers are another type of nanosensor being developed to detect individual molecules. The nanocantilever oscillates at its resonant frequency, so when a particle lands on it, its weight and therefore its resonant frequency changes and this can be measured. It can be coated in antibodies to bond only to specific bacteria and viruses as well for detecting bacteria.
An example of nanocantilevers
An example of some nanocantilevers
  • Nano thermometers are yet another type of nanosensor. These are molecules which fluoresce for a certain period of time, depending on the temperature in a high viscosity environment like inside a cell. These “nano thermometers” are so small that they can be used to measure the temperature of individual cells!

As you can see here, there are a lot of different types of nanosensors. which can detect and measure a wide range of different things. All of these sensors are very tiny and are capable of measuring things at the nanoscale. Scientists are constantly developing new types of nanosensors, and making the current ones more efficient, more sensitive, and cheaper.

How nanosensors are built (nanofabrication)

There are three main ways currently to make nanosensors. These include top-down, bottom-up, and self-assembly. Each method has its own benefits and drawbacks.

  • The top-down method involves starting with a larger portion of solid material and etching out the nanosensor. This is similar to how a CNC machine works. It starts with a solid block of material and cuts away the parts which are not required.
  • The bottom-up method involves assembling the nanosensor, piece by piece, with individual atoms and molecules. This is very similar to how a 3D printer works, by placing down material where it is required to gradually form the desired object.
Top-Down vs. Bottom-Up Nanofabrication
  • On of the most effective methods however, is the self-assembly method. This uses a few pre-assembled parts such as molecules which then automatically assemble themselves into a nanosensor very quickly and cheaply. The pre-assembled parts are usually made with the bottom up method.

The problems with nanofabrication

All these methods for creating nanosensors are great, but there are many problems. Both the top-down and bottom-up methods are difficult to use to mass produce nanosensors. The bottom-up method is very time consuming and expensive, requiring extremely precise tools. The top-down method is a bit cheaper but not as precise.

Potential Ideas to improve nanofabrication

The self-assembly method is currently a much more efficient method. It can be used to produce large numbers of nanosensors quickly. Another potential way to improve nanofabrication could also be to combine the top-down and bottom-up processes. If you were to carve a rough shape with the top-down method (which is cheaper), then the bottom-up method can be used to add the finer details on top (minimizing the amount of work needed by the bottom-up method, which is more expensive). This can be compared to carving out a rough shape of a model from clay, and then refining the model by adding more bits of clay where needed. This is often the most efficient way in the case of clay, so this could possibly work for nanofabrication too. This would both keep the cost lower, but keep all the tiny details required for nanosensors.

I hope you enjoyed this article, and thanks for reading!



Ahsen Khan

I'm interested in coding, new technology, 3D graphics, and everything related to computers in general.