Nanotechnology and Nanosensors

Taking the technology industry like a gust of wind, nanotechnology has truly become the buzzword of the decade. From incorporating into medical science, electronics, clothing, and many more industries — even plots for sci-fi movies! — nanotech is a truly game-changing discovery. While most people know about it, they lack information on what it really is and the implications that it has (you can thank the movies for that). In this article, I will be exploring nanotechnology and one of its biggest branches in detail-nanosensors.

WHAT IS NANOTECHNOLOGY?

Essentially, nanotechnology is described as the study of things such as materials and particles at the nanoscale, which is anything between 1–100 nanometres. To wrap your minds around how small that is, 1nm is 100,000 times smaller than the width of a regular sheet of paper! But the scientists part of the nanotech industry don't just study what happens when particles are this small — that would be boring — they manipulate the materials to change the properties and uses, potentially creating something that can be very useful.

See, when particles are this small, they change. Nanoparticles are different because they have a very high percentage of their atoms are present at the surface of the particle, rather than the inside. For example, copper particles less than 50 nm are extremely hard, opposite to bulk copper particles that are known to be extremely malleable. Scientists use these manipulations to try to make things that have the potential to change our world today. Implications of nanotech include creating better and more wearable fabrics, faster and smaller computer chips, finding ways to detect diseases at the molecular level, and much more. Seeing this potential, nanosensors were made to start with this journey to a more technologically advanced world.

NANOSENSORS

Nanosensors are like any other sensor you might find. You may not notice it, but sensors are a big part of making life more efficient. Think about all the sensors you may find in your daily life. Sensors detect when you are walking and open the sliding door at your local Walmart. Sensors on your phone reduce the brightness on your phone when they sense that the room is dark to make it easier on your eyes. Sensors on the back of your car tell you when the curb is near so that you stop moving. However, what if I told you that these same sensors, incorporated into an amazing form of technology can do amazing things, such as detect microscopic bacteria and viruses, find cancer and other diseases in your body, and find chemical and disease in the air?

WHAT ARE NANOSENSORS?

This is when nanosensors come in. They are essentially sensors set to detect chemical or mechanical properties in nanoparticles; they are just really really small sensors. Nanosensors can be one of either; a sensor in the nanoscale (1 nm- 100 nm) or a sensor optimized to measure quantities and qualities at the nano level, which may or may not have dimensions at the nanoscale. Like mentioned above, they provide insight on nanoparticles by measuring the mechanical and chemical properties of nanoparticles. Nanosensors are:

• Highly sensitive and accurate
• Fast with low response time
• Efficient (small, durable, require low energy input)

DIFFERENT TYPES OF NANOSENSORS AND HOW THEY WORK

There are 2 different types of nanosensors, mechanical nanosensors, and chemical nanosensors. Mechanical nanosensors identify substances by sensing for their capacitance. A minuscule weighted shaft attached to a capacitor bends when there are changes in acceleration, which is measured as a change in the capacitance. Chemical nanosensors measure particles by monitoring electrical changes in the sensor’s material. they can be made sensitive to certain material and immune to others, to find the nanoparticles the user may be looking for.

WHY ARE NANOSENSORS IMPORTANT?

Nanosensors are an important part of technology today due to their capability of interacting easily with other particles at the nano level and are open to innovate a new generation of devices. They are also used in many important fields, as mentioned above, and are part of the new solutions coming up to solve diseases like cancer. Some examples of important direct implications of nanotechnology are in the airbags in cars and sensing for chemical/poisonous elements in the air. Nanosensors are great at sensing electromagnetic radiation, scanning environmental samples, bioimaging, and much more. The future of technology is in nanotech.

NANOFABRICATION

Like every other piece of technology, nanosensors have to be built from scratch. The process used to build nanosensors is called nanofabrication. Nanofabrication is used to build nanosensors and most other nanostructures used in nanotechnology. There are two different approaches to do this, and they both come with their advantages and disadvantages.

TOP-DOWN FABRICATION

“Every block of stone has a statue inside of it, and its the task of the sculptor to discover it.”

This quote by Micheal Angelo is a perfect description of top-down fabrication. This type of nanofabrication involves taking atoms and molecules off material, to create the wanted nanostructure, in this case, nanosensors. The most common way top-down fabrication is done these days is through nanolithography. In this process, the required material is protected with a mask while the unneeded is etched away. Depending on the resolution needed for the final product, the etching can be done mechanically or chemically. Mechanic processes include UV rays, x-rays, and electron beams. The chemical etching is done with the use of acids.

Advantages of top-down fabrication are that the desired features can be put on with great precision, and scalability is also more accurate. However, this type of nanofabrication’s main disadvantage is that there are limitations on the resolution of the nanosensors, due to current cutting and masking technologies not being very good. This equipment is still very expensive and makes this method less cost-effective than the next.

BOTTOM-UP FABRICATION

Bottom-up fabrication is quite the opposite of the previous method. Using the same analogy, this would be a pile of powdered rock, that has to be put together into a statue by gluing the pieces together. This process is additive, while the top-down fabrication method is subtractive. The process is fairly simple; atoms are stacked together, which gives rise to a crystal plane, and the crystal planes stacking on to each other and so on. It can thus be seen as a synthesis process, where building blocks are added to the substrate to create the nanosensor.

The advantages of bottom-up fabrication are that it is chemical based. This allows a large number of chemical entities (atoms and molecules) to be structured to form the nanosensor, giving it a high resolution. This type of nanofabrication is also used to make computer chips. the disadvantage is the limitation on the large scaling aspect of nanofabrication. This process is more cost-effective than top-down fabrication, however, it takes much longer and is less efficient.

NEW WAYS TO IMPROVE NANOFABRICATION

Like mentioned above, the main problem with the two methods is that they are not very efficient, one being costly and the other ineffective with time. However, using new technologies to make bottom-down fabrication self-sufficient, meaning that the atoms with arranging themselves, will make the process much more efficient. In addition, combining the two methods could also solve problems associated with the resolution and scaling; one idea being to possible start with the etching of material but cutting a bit deeper, than coating it using the bottom-down fabrication approach. This would let the outer resolution be high while allowing large scaling to be possible.

CONCLUSION

To end off, I would like to write a quote about the potential of innovation like this.

If you always do what you always did, you will always get what you always got. — Albert Einstien