Nanosensors, looking microscopically into the future ( A Beginner’s Guide)
The idea of nanotechnology was non-existent 60 years ago. Anyone who thought of something that could work at a microscopic level was ridiculed. Fast forward to today, we have nanotechnology all around us; it’s inescapable. Nanotechnology can be found in medicine, electricity, solar power and 3D printing But don’t be fooled, nanotech is very, very, small. Nano, being a prefix, comes from the unit ‘nanometre’, meaning one billionth of a metre. Putting this into perspective, on a microscopic level 10 hydrogen atoms lined up side by side would equal to one nanometre. Having technology function at a microscopic level is key to our future.. Nanotechnology has advanced more than ever before. It has allowed scientists and researchers to develop one of the most disruptive technologies today: nanosensors.
So… what are nanosensors and why are they so important?
Nanosensors are just like any other sensor that works to detect all kind of signals from a variety of environments except they are much, much smaller and are measured on the nanoscale (generally measured from 10–100 nanometres). Nanosensors have the ability to detect nanoparticle data and transfer it to by analyzed macroscopically. There are many advantages to have a nanosensor, some being:
- Faster response
- Better signal-to-noise
- More accurate data
- Increased data density
- Less impact on the phenomenon being measured
As a result, nanosensors are being used in all kind of scenarios including but not limited to, aerospace, combined circuit and most importantly, health. Within the medical field alone, nanotechnology has already made exciting possibilities a reality by being able to do things such as drug delivery, diagnostic techniques, antibacterial treatments and cell repair.
Do all nanosensors work the same?
Nanosensors work in so many different fields because many ones work in different ways. However they all work similarly to the way a human sensing system works.
Nanosensors calculate the displacement, dislocations, concentration, volume, acceleration, pressure or temperature of each cell within the human body. They are made to be able to differentiate between normal and mutated cells for detecting cancer in the body, molecular controllers to deliver medicines in the body. The receptor within a sensor sends out molecules to interact with analyte (substance being measured). Through the data transmitted back to optical or electrical signals, the signals are increased to be displayed and quantified. The mechanism of a nanosensor is similar amongst many types some being biosensors, chemical nanosensors and optical nanosensors.
It is clear that nanosensors, being so new, are already making a large impact on society today. As it continues to be developed, it is inevitable nanosensors will move to being involved with everything we do.
Nanosensor research has been found to have grown exponentially since the year 1994
We know what nanosensors are and what they do, but how are they made?
The process of creating nanosensors is referred to as nanofabrication. Nanofabrication is a broad term that can be split up into 2 different forms; Top-down and bottom-up.
Much like Michelangelo’s process of creating marble figures, Top-down nanofabrication, also known as lithography is the method of taking a block of material and removing the unneeded bits and pieces until the target shape and size is acquired. Other forms of top-down nanofabrication include Electron beam lithography (EBL), Optical lithography and Nanoimprint lithography (NIL). Optical and Nanoimprint lithography are the primary forms of top-down fabrication.
Contrasting the top-down lithography, is the bottom-up lithography. Guided by thermodynamics and kinetics, bottom-up nanofabrication determines the outcome of the desired form. Using tools like chemical synthesis, quantum dots, carbon nanotubes and multifunctioning particles, the bottom-up process can create structures within the nanoscale.There are two major ways in which bottom-up nanofabrication is evolving to take place. These being self-assembly and molecular assembly.
Self-Assembly heavily relies on having designed components required to assemble themselves into specific patterns and functions. These components are coded to a specific shape, surface property, charge polarizability, and mass, and these are used to determine the interactions among them. It is not yet known as to why specific atoms and molecules arrange themselves in set ways, but once they have, they can be controlled to build structures, starting from a singular atom.
Self-assembly has become a valuable concept within nanotechnology allowing for many advances to take place in a variety of industries. IBM took the self-assembly process to use to create air gaps (vacuums) between copper wires on their computer chips. This allows for electrical signals to flow faster, while also consuming less electrical power. This is just one of MANY examples of how nanofabrication advance the society into the future.
Nanofabrication, it’s not perfect just yet
Like all technology, nanofabrication has both advantages and disadvantages to its process.
For top down lithography, the operation is laborious and costly, as well as the tools available are much larger, restricting the development of creating perfectly detailed nanotechnology and risking alterations of the final product. Further, as a result of progressively challenging patterns within the nanofabrication, the advancement of the semiconductor chip used in the top down process is slowing down.
With bottom up lithography, a compatible surface is needed in order for the construction to take place and there are less tools available that have the ability to manipulate the molecular structures. Further, It is difficult to control contamination from the micro-environment around the atoms so chemical purification of the nanoparticles are required and the process is inefficient. This points to a challenge with large-scale production.
Nonetheless, the potential overarching problem that exists within nanofabrication is the lack of accessibility. As a result of both processes being costly, it makes it difficult for those interested to have an in-depth exploration of what nanofabrication truly is.
So, what are the solutions?
Processes of nanofabrication may have their flaws, but scientists are extensively researching the ways in perfecting the process.
- Until recently, there was no way of knowing how to determine the structures that were produced from molecular self-assembly. Daniel Packwoord and his team of researchers found they could use their knowledge of the intermolecular reactions and the temperature at which the reactions take place to predict the kind of structure that is formed. He then partnered with colleagues in Japan and the United Stated to use artificial intelligence to simulate molecular self-assembly on metal surfaces, predicting the outcome of the process with high accuracy. The predictions have high potential in leading to controlled fabrication of nanomaterials for devices in the future. The creation of these devices would also be cheaper, addressing the cost efficiency of nanofabrication.
- A new approach that can remove fabrication defects and improve nanostructures is called self-perfection by liquefaction. By using a flat plate to guide the process, this concept could reduce the line-edge roughness of nanotechnology. It involves melting select nanostructures for a short period of time while simultaneously applying boundary conditions to guide the molten material into the target form before re-solidifying. This method allows the produced nanotechnology to have an accurate pattern and significantly reduces the risk of an altered structure.
Nanotechnology is the future of our society and nanosensors are going to be integral to the future because it has the potential of having a significant impact on people’s quality of life. It is now up to the younger generations to take the knowledge that they have and use nanotechnology to change the world. “The science of today is the technology of tomorrow” — Edward Teller
