Nanotechnology is fascinating but at the same time, it can get quite confusing. Especially when we get into Nanosensors. Before we start, check out this video!
Umm… So What is this “stuff” and what does it mean?
Well, to start of “nano” is a prefix in measurement; one nanometre is just one billionth of a metre. And just to get an idea of how small that is; on hair stand shrunk by 100,000 times is the size of a nanometer. From continuous advancements in science, this is what scientists are able to work with. Nanosensors are nanoscale devices that measure physical quantities and convert those quantities to signals that can be detected and analyzed. They’re not much different from normal sensors- except for the whole nanoscale part. Nanosensors also have various applications, especially in the environmental field and medical field. For example, the detection of bacterias, viruses, and fungi, as well as the diagnosis of cancer. Additionally, the use of nanomaterials in sensors to extract and detect tumour-specific biomarkers or circulating tumour cells holds the promise to detect cancer much earlier and hence improve the long-term survival of the patients.
Seems silly… Why should I care?
Humans are always concerned with evolutions, economic developments and money! Sadly, in the process of bettering the world, we ironically have been hurting it. Human development, particularly after the 1900s has lead to things such as pollution, diseases, global warming and much more. In the near and far future, nanosensors will play a critical role in our technology-minded world.
Nanosensors will also help open up unexplored ideas and concepts and bring a whole new meaning to our capabilities. Notably with the ability to interact at a nanolevel with molecules and observe different processes that are incomprehensible at the micro-level. Furthermore, nanosensors offer portability, low power consumption, faster response, and real-time monitoring. As I mentioned before, this brings all new meaning to the medical field. And the few things I have discussed so far are a mere drop of water compared to the ocean.
Okay, but how is all this possible, how do they work!
Now there are multiple types of nanosensors and different ones are designed for different uses. Think of it as a spoon and fork. Both can be used to eat ice cream, but do u really use a fork? The point you won’t use biosensors for studying space.
Overall, nanosensors can be grouped into two categories- mechanical sensors and chemical sensors- and both have different sensing mechanisms.
Chemical: Nanosensors that detect chemicals work by measuring the change in the electrical conductivity of the nanomaterial once an analyte has been detected. Many nanomaterials have a high electrical conductivity, which will reduce upon binding or adsorption of a molecule. For example: when a molecule of nitrogen dioxide is present, it will strip an electron from the nanotube, in this case, it will make the nanotube less conductive. Nanotubes are a tubular molecule composed of a large number of atoms.
Mechanical: Mechanical nanosensors also work by detecting a change in the electrical conductivity of a material. However, the mechanism for doing so is much different. Nanomaterials that are used as mechanical nanosensors change their electrical conductivity when the material is physically manipulated, and this physical change invokes a detectable response.
Who is the “Bob the Builder” behind all this… and how do we build these sensors?
Well, I can understand how this may seem impossible and bizarre, but let me try to simplify it. Nanosensors are made through a process called nanofabrication. Nanofabrication is the design and manufacture of devices with dimensions measured in nanometers.
Nanofabrication can be loosely divided into three major areas/types: top-down lithography, bottom-up approach, and molecular self-assembly. Each of these is vast subject areas of themselves, but today I will attempt to cover their essential concepts in a concise fashion.
Top-down Lithography: Top-down is essentially the breaking down of a system to gain insight into its compositional sub-systems in a reverse engineering fashion. It simply means that you start with a large scale object and then break it down into nanometers. You can picture it as sculpting.
Nanolithography isn’t much different from normal lithography. It’s the same process of printing and etching onto a plate. You can think of it as printing newspapers and magazines. The main difference is that instead of ink light photons, electrons, and different types of lights(ultraviolet, infrared, etc).
The top-down lithography allows engineers to use a larger variety of materials, but the problem is that it uses a lot of energy and produces a great amount of waste. With top-down lithography, it also gets increasingly difficult as you get smaller in size.
Bottom-up approach: As you can infer, its quite the opposite of the first one. bottom-up fabrication can be compared to building a brick house, but instead of placing bricks one by one, atoms or molecules are placed one at a time to build a nanostructure.
Molecular Self-assembly: This is similar to the bottom up. In fact, the bottom-up approach is a method of self-assembly. As the name suggests, molecular interact by themselves and build each other up. Molecules adopt a defined arrangement without guidance from an outside source. Think of it as a plant growing. Self-assembly uses very highly developed techniques of synthetic chemistry.
Wow, It’s Perfect.
Sadly, it is not perfect and still needs many improvements and is still in the early stages of its development. The general nanofabrication of nanotechnology and nanomaterials is still fairly expensive, and many nanofabrication methods aren’t compatible. All 3 of the methods mentioned above pose problems and obstacles. For example, the machinery cost for top-down lithography. Furthermore, the process of self-assembling isn’t perfect. It is still hard to get the molecules to behave a certain way.
Oh no, how do we solve these problems?
Many teams of scientists are currently working on nanotechnology and finding solutions by putting in hours of research.
Now solutions from my standpoint may not be implemented or even considered. And I understand that since I am only a high-school student without any degree. However, this is what I think we can do.
- Nanotechnology is still in its early stages and has so much room to expand. I believe that observe things in nature may help. Similar to how we are made up of stars. To understand ourselves we need to understand stars(btw I heard this in a Bill Nye video). Hence, I believe to solve the problems of nanotechnology and to further progress, we will need to observe the natural phenomenons and look at nanotech from different viewpoints.
- Secondly, I believe the self-assembly process will prove very beneficial. It is much cheaper and much more convenient.
- Lastly, to improve the processes of nanotech and nanofabrication, we need to inspire others. The more people we have working on this the faster we can solve all the problems. Different clubs and events can inspire teens and even adults to study and learn about nanotechnology.