Chapter 7: Sensors and sensibility

In the last few posts I have been focused on telling you what I have been up to, from a trip to London to starting my new project, but this week will be a little different (exciting I know). For the last 2 weeks I have been reading up around my new project so that when I start in the lab next week I actually know what I am talking about, or at least can pretend I do. I have been reading papers almost exclusively about biosensors; which is a key part of my new project. Since all I have done is read about them I thought that telling you what they are is pretty much a summary of what I have been doing during the last few, rather uneventful, weeks. Below I’ve created a condensed version of the basics about biosensors, namely what they are and why I am interested in them. 

The bits and pieces

To start with it’s probably best to know what a biosensor is. To break it down: bio- means something biological, and sensor- meaning something which detects or senses something (I know you’re not supposed to use the word you're defining in the definition but in this case it is hard not too). Essentially this boils down to give you an idea of what a biosensor is: an analytical device which measures something that you are interested in and a part of that device is biological.

To understand a biosensor and how it works it is best to look at all the different parts individually (shown below with the help of cartoons, the best way to learn). Firstly, you have the thing that you want to measure/detect, this is your target (1). To be able to detect this target we need something that is going grab onto the target and tell us that it is there. This is our bioreceptor (2). This bioreceptor is designed so that it can only grab onto the target and nothing else. When a sample of something (e.g. blood) is put on the sensor and the sample contains the target it gets stuck to the bioreceptor, this is called binding (3).

Figure 1.png

An example of this would be glucose in blood. When you have a sensor which is designed to detect glucose you put a blood sample in and an enzyme on the sensor grabs the glucose in the sample. When the target is there and binds to the bioreceptor it causes a in the receptor, this leads us to the next step.

When the binding happens the receptor creates a signal (4). This signal can be anything; it can be a physical signal, where the bioreceptor changes shape, or it can be chemical, where binding causes the release of another chemical. This signal varies depending on the kind of target and the type of receptor. Either way the binding has caused a signal, now we have to turn that signal into something more meaningful. This is where a transducer comes in (5).  A transducer is a device which turns one thing into another, usually it turns one form of energy into another. In this case the transducer turns the signal from the bioreceptor into another signal which can be more easily understood by our next component- the detector. The detectors jobs is to detect (who would have guessed?). It detects the signal from the transducer and creates an output which tells us if the target is there. This can be as simple as a yes or no answer or it can be more complicated and tell you exactly how much of the target is in the sample.

Figure 2.png

Once again using our glucose example, if glucose is in the sample it binds to the bioreceptor, this produces a chemical signal, this signal is then turned into an electrical signal. This electrical signal then tells our detector how much glucose is on our bioreceptor. Then an output is produced which tells us exactly how much glucose is in the blood sample. To summarise this whole process I’ve put all the panels together and written a flow chart below to make it easier to see:

How a biosensor works: the target binds to receptor-> the receptor produces a signal-> the signal is carried to a transducer-> the transducer signal is detected and creates an output.

How a biosensor works: the target binds to receptor-> the receptor produces a signal-> the signal is carried to a transducer-> the transducer signal is detected and creates an output.

Biosensors are bio-awesome

While you now hopefully understand what a biosensor is, you might want to know why we use them. There are a whole bunch of uses for biosensors, far too many for me to fully discuss here; but there are two obvious ones. Firstly, diagnostics. If you are sick we need to be able to find out what kind of illness you have, so that we know how to treat you. This is where biosensors can be useful; they can help identify what is wrong with you and what the best treatment might be. I keep mentioning it but glucose is one of the most well-known examples. If you have diabetes it is important that you keep an eye on the glucose levels in your blood. A biosensor can be used to monitor this rather than having to continually take blood samples or just guess the best time to give you treatment. 

The second use is particularly relevant given the current global climate- environmental monitoring. Sustainability and awareness of the environment  has thankfully grown over the last few decades.  Thanks to technological advances, as is the case with biosensors, we can  measure what damage is being done. In this case a biosensors can be used to check if the water contains pollution or harmful bacteria. This is useful because we can use it to make sure that we aren’t doing anything which damages the environment and check that when we try and help the environment we don’t accidentally make it worse.

In general biosensor are a field of research that is made up of different areas of science; it’s a bit of a hodgepodge, which is possibly my favourite word of the day. It is part chemistry, part biology and part physics. This is one of the reasons I enjoy; much like a box of chocolates you never know what you are going to get (side note: sorry Forrest Gump you are a great movie but that is a terrible analogy). Still, biosensors are a cool bit of tech which are only going to become more and more useful as technology develops,  which at least in my mind makes them exciting.

For now, that is enough of me gushing over why I like biosensors. Hopefully you have learned something about biosensors, if not I best get better at talking about then since the next 3 years of my life will be focusing on them. Until next time this is Steve the Scientist signing off.