Nanosensors: The world’s greatest detectives
Great things sometimes come in very small sizes. This is particularly true when discussing nanotechnology. Over the last decade, substantial research and development has gone into nanotechnology. But, what is nanotechnology? The term, “Nano” often refers to objects measured in billionths of a meter, or “nanometers”. To put this scale into perspective, a single sheet of white paper is approximately 100,000 nanometers thick and a strand of hair is approximately 30,000 nanometers. So basically, nano means tiny, but why do we care? Nanoscale materials are interesting to the scientific community because some material properties can change at this scale, such as conductivity, reflectivity and magnetism change compared to larger bodies. The smell of freshly baked cookies operates on nanoscopic scale.
What are Nanosensors?
When you hear “nano” you are probably going to imagine something extremely tiny. However, with some technologies such as nanosensors the nano isn’t referring to their size but rather the scale at which they operate. What are nanosensors, and why do they matter? Nanosensors are extremely sensitive sensors that can detect particles at the nanoscale. An example of this, is the detection of nano-sized airborne contaminants or the particles associated with the smell of freshly baked cookies. What makes nanosensors unique is their ability to detect physical, chemical and biological particulates with sensitivity, specificity and speed. This has multiple applications that can impact health, safety and the environment.
Why are they important?
Nanosensors are unique because by operating on such a small scale they yield faster responses, better signal to noise ratio, more accurate date, increased data density and less impact on the phenomenon being measured. This makes them extremely useful in fields such as health, environment and safety. These technologies are already being used today is several very useful capacities. The best way to describe the importance of nanosensors to discuss their utility through an example.
According to Dr. Sangeeta Bhatia, about two thirds of the cancer deaths worldwide are preventable by techniques that we have at hand. You may be wondering “if that is the case why aren’t cancer mortality rates lower and what does this have to do with nanosensors?”. However some patients cancer diagnostics are often discovered too late and treatment options are limited. Nanosensors have the potential to save thousands of lives through early detection. In 2009, a group of Yale researchers were able to diagnose cancer for the first time using whole blood.
Nanosensors are also useful in the environmental field, they were used during the Beijing olympics to measure solar irradiance, aerosol cloud interactions, climate forcing, and other biogeochemical cycles of East Asia and the Pacific region. This technology was used to predict weather patterns and conditions, which facilitated the planning of the event. Nanosensors are also used to analyze emissions of car engines by car manufacturers to meet safety standards.
How they work
As the name implies, nanosensors can detect information and data, but unlike ordinary sensors they are developed at the nanoscale, therefore making them more sensitive to nanoparticles. They can measure minuscule differences in volume, acceleration, temperature and concentration of different materials. There are so many different types of nanosensors and different applications, it is impossible to describe them in great detail. Let’s say you wanted to use nanosensors to detect the smell of freshly baked cookies, you would need a chemical nanosensor. Chemical nanosensors work by measuring the change in the conductivity of the nano-material. So, in our scenario the chemicals that the cookies give off would change the conductivity of the air and the sensor would detect that change and identify the smell of freshly baked cookies.
How they are built
Nano sensors are made through nanofabrication, which is the manufacture of a device measured in nanometers. I cannot go into much specific detail as what needs to be taken into consideration and the manufacturing process differ depending on the type of nanosensor. When manufacturing nanosensors to be used on cells many things have to be taken into account such as cell type, electrode folding and the nature of the components of the cell which are being sensed.
At present, scientists use electron-beam lithography or focused ion beam milling to create patterns at nanometre length scales. However, such techniques are not practical for mass production because they must start from scratch each time and the patterns cannot be made over large areas. Moulding, imprint lithography and soft lithography can mass produce patterns, but these methods are limited to the fixed features on the mould or the original master template. One of the ways this technology can improve, is by combining the technologies of 3D printing and electron-beam lithography. This way nanosensors can be mass produced and once mass produced this will pave the way for more innovations in the future.
