Commercialising graphene: Graphene oxide biosensors
What is a biosensor? Ladies, bear with me for a minute. Prostate cancer is the most common cancer in men in the UK and worldwide. Catch this cancer early and you can be cured.
Identifying prostate cancer involves taking a blood sample then sending it away to be analysed in a laboratory using tests that detect prostate specific antigen (PSA). Wait a couple of weeks and a return visit to the doctor will get your results.
Now, imagine you had a device that can detect PSA in seconds and give you a result there and then. That is what a biosensor can do and a rather smart researcher, Dr Vivek Pachauri and his team have developed a sensor that can do just that.
I get to talk to people about their work with cutting edge science and technology. That’s one of the joys of my job. This week I’m talking with Dr Vivek Pachauri, who has recently returned from presenting at Graphene 2017 held in Barcelona, Spain. This conference is the main meeting point of the graphene community worldwide.
Vivek’s first degree was in Biology, he followed this with an MSc in Chemistry then a PhD in physics from EPFL while carrying out his research on nanoscale electronic sensors at the Max Planck institute. This blend of the three big sciences is important because the work he does spans these disciplines. So what has Vivek done with this impeccable academic background?
Vivek and his colleagues at the University of Applied Sciences, Kaiserslautern have made sensors from a variety of nano scale materials. The chemistry and physical shape of these materials (the template) can hold various target compounds when exposed to a sample. Only the target sample affects the electrical properties of the template in very specific ways that can be used to identify whether the sample contains a specific target, such as prostate specific antigen.
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The team is working with a variety of these nano scale materials one of which is graphene oxide. They start with graphite and have developed a highly tuned chemical process that creates graphene oxide. This is then reduced back to graphene by heating to create the material. Careful adjustment of the heating gives the team control over the balance of graphene and graphene oxide in the material and this is one of the ways they create the selective sensitivity they need to detect various target compounds.
So much for the detector material. To create the sensors the team turns to techniques you’ll be familiar with from the semiconductor industry. They start by spin coating the graphene/graphene oxide material as a very thin film on to a wafer made from silicon or glass. Once this layer is dried it is printed with a photoresist that is cured. This surface coating is etched back to the glass apart from the areas where the photoresist was printed. Once this is cleaned away the process can be repeated if needed to create microscopically small structures that are the sensors.
These sensor chips are remarkably consistent and stable devices. Being so small they are very sensitive too. They can be mass-produced because the printing technology used is mature and well understood. The photograph below shows a wafer printed with these devices.
So what does all this mean? Well, Vivek’s team have created sensors that can be mass produced opening the way to making devices that can detect a range of target compounds, not just cancer indicating PSA. These sensors are potentially a cheap, sensitive and reliable basis for a range of hand held devices of the future. This seems to me to make a good commercial proposition for a start up company. I’m keeping a watching brief on what this team does next; they just might be on to something.
Adrian Nixon began his career as a scientist and is a Chartered Chemist and Member of the Royal Society of Chemistry. As a scientist and ... <Read more about Adrian Nixon>