The Key To Technological Advancements

An article dedicated to nanotechnology and nanosensors.

Imagine a world back in the day where automatic doors didn’t exist, or where humans were generally less informed about their surroundings. Thankfully, the world has changed drastically. This change can be partially awarded to the developer of nanotechnology.

Eric Dexler is said to be the developer of nanotechnology, however others say that a physicist named Richard Feynman made several ideas and concepts relating to nano-science back in 1959. There are several theories on who came up with the idea of nanotechnology. The important thing to recognize is that, nanosensors have shaped the way we find information in our society. Fascinating right?

So why are nanosensors important?

Nanosensors have made their way into several industries including but not limited to the medical field, agriculture, prognostic and diagnostics. Naturally, its application changes depending on the industry.

Medical Field Applications

1. Identify subatomic particles of viruses.
2. Measure the temperature of biotic cells- measure temperatures in ex vivo tissues and can measure the heating effects of ultrasound. Using wire gages.
3. Improve medical imaging to detect smaller particles that could lead clinicians to finding the health issue.
4. Monitor levels of bacteria/viruses- using carbon nanotubes or nanowires.
5. Doctors are even trying to create nanosensors that act like human cells. Subsequently, a group of doctors have tested growing nanosensors onto hip implants to see if bone cells are attaching themselves onto the implant versus bacteria and inflammatory cells. This clearly depicts how the nanosensors are important to the future of healthcare because it could increase the efficiency of hip implants and many more surgeries for patients.
6. Nanomaterials that are smaller than 20 nm have the capability of moving beyond the blood into the body’s circulatory system. Thus being used for accurate drug delivery. Such as moving therapeutic genes to malignant cells while keeping healthy cells intact.
7. Skin ulcer healing, bone tissue engineering, cancer treatment through drug delivery. These nano materials are efficient and sensitive.

As you can see, the nanosensors available in the medical industry allow us to live safer lives. Medical professionals are now more educated on the behaviour of viruses, thus leading to us to a safer world. Not to mention, nano-sensors can fasten the process of diagnosis which can even save peoples lives!

Agriculture and the Food Industry Applications

1. Ability to sense chemical and biological agents in the air and water.
2. They can detect mercury in any medium!
3. Track water distribution and quality. Will make water flowing through pipes efficient and save water too. This is vital as climate change is affecting water levels so we need to preserve the way we use water as we cannot create or destroy it.
4. Quality check — food component detection. Detect food hazards such as melamine affair in 2007/2008.
5. Plant adaptation to climate without harming surrounding ecosystems.

Nanosensors in the agricultural industry are helping people grow safe and sustainable food for our growing population.

You might be wondering, what exactly is a nano-sensor?

Nanosensors are miniscule pieces of technology that are able to perform several tasks. Although the term “nano” refers to something being tiny (one BILLIONTH of a metre), this does not impact the applications that they are capable of! Nanosensors are devices that detect, quantify and measure particles. They simply use nanoscale materials to detect biological and chemical molecules. Achieving information on a nuclear scale and shifting the information into data/info to then be analyzed.

It’s evident that more research concerning nanosensors will lead to more brilliant breakthroughs in science! There is no perfect definition of what a nanosensor really is because there are so many smaller categories in the field of nanotechnology, that the definition for each field would be completely different than one another.

A visual representation of what a nano-sensor might look like.

How do they work?

Nanosensors work by using electrical changes and signals that are given off by nanomaterials(nanoscale materials are materials that have atoms upto 100 nm). There are several methods that allow nanosensors to work depending on their purpose. Chemical nanosensors contain nanotubes and/or nanowires. These are able to measure the change in electrical conductivity once the analyte (a substance that is being identified and measured) is detected. Since many nano-materials have a high electrical conductivity, it reduces the changes of the absorption or binding of a molecule, therefore, what is being measured is simply the detachable itself. For example, say there is a carbon nanotube present in a sensor. When a molecule of nitrogen dioxide is present, it will take away an electron from the carbon-based nanotube which results in the tube being less conductive.

This whole process sounds confusing but if you understand that when an analyte meets the receptor in the nanotube, the receptor sends signals to the transducer which then converts the information into relevant information that scientists can then quantify and measure.

On the other hand, mechanical nanosensors also work by detecting the change in electrical conductivity however this sensor relies on the nanomaterial’s electrical conductivity once it has been physically manipulated. This manipulation changes the conductivity therefore resulting in a response that can be measured using an attached capacitor. Interesting stuff! Think of mechanical sensors as a cause and effect. You have to introduce a physical manipulation to the nanomaterial in order for you to get relevant information.

Carbon nanotube visual

Here are a few types of nanosensors:

1. Chemical — measuring concentrations
2. Physical — measures properties such as displacement, stress, temperature etc
3. Biosensors — biologically active substances
4. Mechanical
5. Optical

Now that you know a little about how they work, let’s move onto how they are built!

How are they built?

Nano-fabrication

Nano-fabrication is exactly what it sounds like. It’s simply the design and construction of nanostructures so that they can be used to create devices, systems and more(such as the nanosensor). So, the term nanofabrication can be divided into the following 3 categories.

1. Thin Films — the state of the thin films affects the behaviour of the device. All material properties are dependent on the thin film stress. Thin film stress deposition happens by using a state of the art procedure called open loop stress management.
2. Lithography- common in the semiconductor industry and it’s pretty much taking a large piece of material and reducing it to the size of a nanostructure. Then you go onto pattern making.
3. Etching- a subcategory in the nanolithography section where you print, write and etch patterns onto the nanostructure. Chemicals can be applied to the nanostructure and precise waves of light/electrons/xrays/ and UV light damage the chemicals and result in a pattern. Once the pattern is made, it gets transferred onto a silicon base layer using other lithographic techniques.

Top down and bottom-up technique

Since I already discussed what the “top down approach” is, let’s look at what the bottom-up approach consists of.

The “bottom up” approach is basically taking singular atoms or molecules and forming them into nano-structures.This stacking method results in crystal planes which continue to stack onto each other, eventually forming a nanostructure. In addition, another method is referred to as “self assembly”. Self-assembly is simply is having self-organizing processes. Including proteins that fold together naturally. However, this process is still just a theory!

Top-down vs Bottom-up

A brief look at the advantages of the two common approaches

Top down:

• Used often in micro-fabrication
• Well developed techniques
• Are able to control shape and size of the structure
• Less costly

Bottom-up:

• Ability to build smaller structures compared to top down technique
• Large scale parallel fabrication through welding
• Produces nanostructures with less defects and more homogenous chemical composition
• Many say it’s more effective than the top down approach

Although there are some super cool approaches to nanofabrication, there are some problems with the process.

Problems with nano-fabrication

Since I just listed some advantages of the two techniques, let’s go over some of the disadvantages and problems related to nanofabrication. As nanotechnology is a newer concept, many people are yet to grasp the idea to a mastery level therefore there are still various problems within the nanofabrication process. In X Ray lithography sometimes the energetic electrons heat the water and cause an expansion in the pattern which can ruin the effectiveness of the nanostructure. This demonstrates that nanotechnology is in it’s growing stage, the amount of information that scientists have about the subject will only increase by constant experiments and research. This means that the problem is the lack of detailed information. Although there is already lots of good information available, in order to make nano-structures with no problems, there must be more advancements in the science itself.

Other problems include:

• Expensive tools
• Access to resources is difficult
• Need detailed knowledge to make the right decision
• Takes lots of time to create even a single nano-sensor

Ways to improve the process of nano-fabrication

I think it would be beneficial to make a device like a machine that is able to mass produce these nanosensors. Using AI to remember the different types of lithography for the pattern etching so you don’t have to start from scratch every single time. This would save time, money and effort.

Thank you for reading this article, and I hope you learned something interesting about nanotechnology and the potential that this science has!

If you would like to further your reading, you can read these references that I used to write this article.

Resources

https://www.azonano.com/article.aspx?ArticleID=1840 2

https://www.fierceelectronics.com/sensors/adi-bay-area-startup-team-nanosensors-for-disease

https://www.hilarispublisher.com/open-access/nanosensors-for-chemical-and-biological-and-medical-applications-2161-0444-1000515.pdf medical industry applications

https://www.medicalnewstoday.com/articles/299663#A-doctor-inside-the-body — M. news https://www.sciencedirect.com/topics/materials-science/nanosensors super cool article on applications and HOW it works

https://www.azonano.com/article.aspx?ArticleID=4933 how it works

https://www.nano.gov/sites/default/files/Nanosensor%20Fabrication%20NSF%20June%2013%202017%20final.ppt.pdf nano fabrication

https://www.researchgate.net/post/What_is_the_difference_between_top_down_and_bottom_up_methods_for_creating_nano-structures advantages

https://www.nanowerk.com/nanofabrication.php