Nanotechnology and Nanosensors- Our Future as a Society?
When I was younger, I watched an episode of “Phineas and Ferb”, in which the antagonist, Dr. Doofenshmirtz created a shrink ray. In the episode, this creation was seen as stupid and preposterous, but, it’s not.
The idea of making something minuscule or microscopic may seem ridiculous at first, however, that statement is simply not true. Nanotechnology refers to the manipulation of matter at the ‘nanoscale’ (For context, a nanometer is approximately a millionth of a millimeter), combining science, engineering, technology, and mathematics to create something revolutionary.
Everything around us, whether it be our vehicles, electronics, or even our pets, are made up of matter. Everything depends on the individual atoms around us and their structure. This is where nanotechnology comes in. It is possible to manipulate the very structure of matter so that new products are created from old materials. Nanotechnology references the very essence of science, and is something that is needed to advance as a society. This is also when nanosensors come in.
What are Nanosensors?
Nanosensors take the idea of nanotechnology and apply it to the creation of devices that can measure and analyze the quantities (i.e. mass, volume) of objects. These devices then convert these quantities into signals that can be analyzed. Nanosensors are capable of presenting information about how nanoparticles act at the, as the name suggests ‘nano level’. In order to be a considered a nanosensor, the device must either be able to perform measurements within the nanoscale level or be nanoscale in size.
How do they work?
In regards to how they work, there are two primary types of nanosensors: Mechanical and Chemical, which both act slightly different. Chemically-based sensors detect changes in electrical conductivity of the nanomaterial being measured. Once an analyte or chemical species has been detected, actual analysis of information can ensue. Chemical sensors typically contain two components: Physiochemical Transducers and Chemical Recognition Receptors. The receptor acts with the analytes in order to alter the physical properties so that the transducer can analyze the material. Due to the nature of nanomaterials being high in electrical conductivity, this type of sensor is extremely efficient.
Mechanical sensors also detect changes in the electrical conductivity of nanomaterials, however the process in which this is done is quite different than that of the chemical sensors. Mechanical sensors require physical manipulation of the material being measured, which allows for the sensors to pick up on the electrical changes caused by this process. Mechanical nanosensors measure physical and chemical properties in a nanoscale region or detect the presence of (bio)molecules based on the principles of mechanics, a topic which explains the conditions required for activity and rest in particles due to Newton’s Third Law of Motion (Referencing forces and how they work).
Nanosensors are also classified in accordance with the type of energy signal they detect, whether it be physical, chemical, or biological.
The Significance of Nanosensors in an Ever-Evolving World
Whilst they may be small in size, they are certainly not small in power. Nanosensors offer efficient ways to interact at the nanolevel.
The possibilities for nanosensor technologies are endless, with various medical, agricultural, environmental, societal, and military-based opportunities at hand. Let’s talk about just some of these prospects;
Food Security and Safety:
2008 — Melamine Milk Affair: 300 000 victims, 54 000 hospitalizations, 6 deaths.
2009 — Peanut Corporation of America Salmonella Contamination: 714 victims, 9 deaths.
What do those incidents have in common? They were all food safety accidents with devastating outcomes. We can change the world of food safety simply by enacting the use of nanosensors. Nosang Myung, a professor at University of California is working alongside Nano Engineered Applications (NEA) in order to detect air-borne contamination through the use of nanosensors. By enacting the use of functionalized carbon nanotubes and nanosensors, this device is expected to identify up to eight toxins, with more progress on the way.
Nanosensors offer significant improvements in selectivity, speed and sensitivity compared to traditional chemical and biological methods. They can be used for determination of microbes, contaminants, pollutants and food freshness. — Enisa Omanovic-Miklicanin, University of Sarajevo
Medical:
In 2017, in Canada, 206 200 people were diagnosed with some form of cancer, with 80 800 of those diagnosed dying. The earlier a tumour is detected, the more likely survival is. It’s not always easy to discover a tumour early on but, we can change this. By examining the fluorescent properties of Cadmium Selenide Quantam Dots and allowing them to act as sensors, we can open up a new world of tumour detection, saving thousands upon thousands of lives. The possibilities for nanosensors and medicine are seemingly infinite — Think about it. It’s like a tiny doctor in your body.
“We think there’s a strong promise for nanotechnology that’s used in medicine, obviously because the small size allows you to penetrate cells, get inside cells and manipulate their function in ways that you can’t do with conventional material.” — Prof. Thomas Webster, Northeastern University
Military:
Chemical warfare is a dangerous possibility, and in the case of an attack, we need to be able to take preventative measures and ensure the safety of those in the impacted areas. Gas molecules can be distinguished by factors such as their mass, which is something that a nanosensor can read. This factor also has environmental applications as we can use this technology to see how toxic our air, food, or water is.
Poverty:
If you’re reading this article, chances are you’re in the top 1% (in regards to money) of people in the world. An estimated 50% of individuals around Earth live off of less than $2.50 a day, with 1.3 billion of those people living in extreme poverty (Less than or equal to $1.25 a day). Often, those people do not have access to clean water, food, or medication. Nanosensors can help bridge the divide between the top 1% and the bottom 1%. Nanosensors can use their small size to measure the quality of drinking water preventing water-poisoning and can help check toxins within food. Meanwhile, quantum dots could detect HIV molecules in the early stages, opening the way for treatment and reducing the number of new cases. When individuals don’t have to worry about their health, they are more likely to focus on other priorities, helping them to escape the vicious cycle that is poverty.
Nanofabrication — The Good, The Bad, and The Dirty
Nanofabrication refers to the creation of nanotechnology, including nanosensors. As with everything, building nanosensors can be approached through different perspectives. There are two primary ways of constructing such a device; Top Down Fabrication and Bottom Up Fabrication.
Top Down Fabrication, as the name suggests, refers to the construction of a nanosensor from the top of the structure to the bottom. There are a plethora of ways to engage in top-down fabrication, however, the most common is nanolithography, which can also be split into different subsets, such as optical nanolithography, electric beam lithography etc… In order to understand this process, some context must first be given. The term nanolithography originates from the greek work ‘nanos’, meaning ‘dwarf’, ‘lithos’, meaning ‘rock’, and ‘grapho’, meaning ‘to write’. This means that nanolitthography can be translated to ‘tiny writing on rocks’, which is exactly what this process refers to, as according to AzaNano.com, “Nanolithography is the science of etching, writing or printing to modify a material surface with structures under 100nm.” A substrate is placed underneath a thin film (occasionally seperated by a semi-conductor) and a type of planar called a resist. Other materials are involved however, the aforementioned mediums are required for the nanosensors to work. The materials required for the nanosensor are protected by a mask, while the exposed material gets etched away. The ‘etching’ process varies on a case-by-case basis, depending on what level of resolution is required for the nanosensor. With this in mind, the linocutting of the material can be done through ultraviolet light, light-coupling, nanoimprint technology etc… The Top-Down approach has it’s benefits. It is very cost-efficient and the shape of the structure is controllable however, it is not as effective as the bottom-down approach, which can later cause problems.
Bottom-up fabrication refers to the process of building a nanosensor from the bottom of the structure, to the top. This technique uses chemistry to place molecules or atoms one at a time to build the nanostructure. Bottom-up fabrication has many advantages, as this process is more likely to produce nanostructures with less defects and a more homogenous chemical composition, however, this process is not cost-effective, and can require a multitude of financial assets.
Improving Nanofabrication
As with anything, there will always be room to grow and improve. Nanofabrication has its downsides, such as the cost V.S efficiency dilemma, and scientists are actively looking for ways to improve this technique. In this section, I will be bringing up scientific ideas for improvement to the Nanofabrication process, and also add in my own input.
Enter Molecular Self Assembly. This term refers to the choosing of molecules to perform spontaneous interactions with one another. This process cannot be controlled directly, so scientists have figured out a way to have some indirect power; by choosing the routes and temperatures of the intermolecular interactions. This is chemical (deciding the direction of the molecules) and entropic (deciding the temperature of the molecules) control. Up until recently, this process for overlooked, as due to the sporadic nature of molecular self-assembly, researches could not make the link between entropic control and the structures being produced. However, there is a connection between molecules and chemical and entropic control. When the entropic control is weak, chemical control takes over, and allows for the molecules to assemble in the direction of open-spaces. When entropic control is strong, the molecules will randomly disperse, as chemical control no longer holds any power.
In my opinion, the idea of molecular self assembly is revolutionary but, it is not yet ready to be the primary construction tactic for nanosensors. We need to figure out a way to intergrate machine learning, as both molecular self assembly and machine learning act somewhat on their own, thereby complementing eachother. Whilst some research facilities have looked into making this possible, it has not yet been made a priority, even though it could allow for the integration of automated nanotechnology.
Final Thoughts
Before looking into this topic, I would have never guessed the benefits of such miniscule devices. I truly do believe that as a society, nanotechnology and nanosensors are the next step into our advancement as a Type I civilization (In accordance with the Kardashev scale). The possibilities are endless for nanotech, and because this is a relatively new prospect, we do not know how large the impact of nanosensors and nanotechnology will be. That being said, I do think that the research and production nanosensors and nanotech is absolutely essential, and something that needs to be pursued. Hopefully, you feel the same way as well.
Further Reading
If you enjoyed this article, or are interesting in learning more about this topic, feel free to check out the sources below. In addition, if you would like to see how much you learnt, try the quiz listed down below.
QUIZ: https://www.surveymonkey.com/r/93L5M8R
Further Reading Links:
