The Future of Technology: Nanosensors & Nanofabrication
Nanotechnology is in the midst of becoming an integral part of our future and how we, as a society, get things done. This technology works with objects and materials at a nanoscale.
To put it in perspective: a sheet of paper is about 100,000 nanometers thick, so a nanometer is pretty small.
Though seen as something out of a fiction book, nanotechnology is very much a reality, in fact it’s being put in practice right now; in medicine, environmental development and agriculture.
In our day to day life, sensors are used everywhere: in stores to detect stealing, to determine how fast your car is going on a road, and even to identify your face to unlock your phone.
Just as you may have guessed, with nanotechnology comes nanosensors.
But, what exactly are nanosensors?
Nanosensors are super small sensing devices that collect information and data at a nanoscale. They work by identifying changes in the electrical conductivity of active sensing materials.
There are two main types of nanosensors – mechanical and chemical, both very similar but posses distinct differences that set them apart.
Mechanical nanosensors work by identifying changes in electrical conductivity. This sort of nanosensor actually changes it’s electrical conductivity after physical manipulation of the material — this is what triggers a detectable reaction. To measure this response, we use an attached capacitor which measures the capacitance (the ability of a system/body to store electrical charge).
For example, using MEMS (microelectromechanical systems) washing machines are able to sense their temperature and water levels often by sensing the change in pressure.
Though similar to the former, chemical nanosensors are different in the sense that they are used for detecting chemical changes instead of things like a materials force or temperature.
Nanomaterials often have a high electrical conductivity which can lower when molecules are absorbed or bound together — this is what creates a measurable change. Chemical nanosensors can be fabricated to where they are either more receptive or immune to different materials.
So why are they important?
Nanosensors are vital to the progression of nanotechnology.
They are ultra sensitive to changes at an atomic level, which makes them even more useful and accurate than the typical sensors we use now.
They’re more efficient as well because of their small size, extreme durability and they require low energy. Nanosensors are fast and more responsive which gives them the ability to transmit real-time data. Overall, they are extremely useful in modern day life.
Because of nanosenors’ size everything is massive in comparison which allows them to explore more of a surface area and detect different things at lower percentages and amounts.
But what ‘things’ exactly?
- Chemical nanosensors are enabling scientists to detect small amounts of airborne bacterial contamination and chemical vapors.
- Nanosensors are being used to identify the early onset of cancer.
- They also facilitate diabetes blood diagnostics.
Police use trained dogs to sniff out different substances, now scientists are using nanosensors to sniff out different viruses.
Nanosenors are helping evolve technology in health care… and possibly even space exploration. Right now, scientists are developing a way to detect extraterrestrial life using mechanical nanosensors.
Nanosensors are not only being used in healthcare but also in food quality control, auto safety and environmental pollution detection.
These little machines packs a lot of power in infinite domains!
How do we build such a technology?
Currently, to create nanosensors we use a process called nanofabrication.
There are two main types of nanofabrication; the top-down method and the bottom-up method. Neither are perfect and come with their own set of advantaged and disadvantages.
Top-down fabrication
With this approach to nanofabrication, scientists take on the role of a sculpter. The same way Donatello chipped away at marble to create a statue of St. George, scientists remove material until they achieve their desired structure — or in this case, nanostructure.
Most commonly, to create the nanostructure, material is etched away. Ethinching involes removing the material either physically (with uv lights or x-rays) or chemically (with acids) by using a technique called nanolithography. Nanolithography, by definition, is the science of etching, writing or printing to modify a material surface with structures under 100nm. To preform nanolithography the material is first coated in a chemical substance called photoresist, then, the required material is covered with a mask; the exposed areas of the material harden and get shaved off.
Bottom-up fabrication
This approach is the complete opposite of the former; instead of removing material we’re adding, or more appropriately, building. Atoms are placed one at a time by scientists to create molecules which later create the desired nanostructure. The traditional bottom-up method is a really time consuming process so a molecular self-assembly technique can be used instead. In short, this is where the nanostructure is able to build itself up thanks to the chemical forces between molecules, simulating a biological occurrence which happens naturally in nature.
Advantages vs Disadvantages
Now let’s summarize the advantages and disadvantages tied to these two forms of nanofabrication…
The top-down method is fast which makes it ideal for commercial production but there is a lot more room for error as it’s difficult to convert materials to a nanoscale. It’s also much more expensive than its counter because the cleanrooms (rooms containing few particles with a sophisticated air filtration system called HEPA) and machines needed to complete the process cost a lot.
The bottom-up method is a significantly more tedious process to reach the end goal but it’s able to create smaller product with fewer room for errors and defects. A major plus? It’s a lot cheaper.
Both nanofabrication methods can be subjected to fouling.
Fouling, in a nutshell, is the gathering of unwanted, usually airborne, particles (like dust) coming in contact, gathering or becoming part of the sensor. If there is a case of fouling, the sensor can become easily clogged which makes it less efficient or completely unusable.
Nothing is perfect… but we’re working on it
Nanosensors, nanofabrication and nanotechnology in general are relatively new compared to other technologies but that hasn’t stopped it from growing and transforming exponentially.
Despite it’s supersonic evolution over the last few years, it isn’t without it’s flaws.
Other issues?
There is one other pressing issue within the nano-development world — a lack of people to develop it! Compared to other technology fields like biotechnology and computer sciences, there is a distinct lack of people involved in the field.
My solution?
I think we should:
- Work on the development of self-assembling nanosensors. I think more research need to be devoted to figure out how to come as close as possible to the naturally occurring self-assembly of atoms and molecules.
- Use nanophotonics to cut materials in to even smaller pieces. To do this we’d use lasers significantly smaller than the ones currently being utilized. Smaller lasers would make cuts (during top-down nanofabrication) more precise.
- Fine tune the filtration system in cleanrooms. Right now, HEPA filters are able to filter any particles larger than 0.3 microns which, albeit very small, can still permit particles to make contact and interfere with the nanofabrication process.
- Expose more people to nanotechnology. Kids in school are already barely exposed, if even at all, to new technologies. I believe that secondary and post-secondary students should be motivated and encouraged to pursue an education as well as jobs in the nanotechnology field.
- Combine both nanofabrication methods. Combining both the top-down and bottom-up techniques can allow scientists to harness the positives from both types of nanofabrication, like the speed of top-down and the accuracy of bottom-up.
In summary…
The future of sensor systems, healthcare and, well, the world will soon revolve around nanotechnology. Regardless of it’s flaws, this disruptive innovation will soon leave no stone un-turned and change how everything in our quotidian life funtions.
Despite how small nanomachines are, they’ll be making a massive impact!
Are you ready for the revolutionary change?
