12/09/2022
We’ve now finished making the first JNT probe using graphene as the sensor material. Earlier probes were all made using wound nichrome wire, leveraging the existing and well-established manufacturing techniques used in PRTs. Our ideal resistance is around 5kΩ, which means that the resistance wire is both very thin and relatively long, so we were concerned about manufacturability and durability. On the other hand, graphene looks like an almost ideal material, having as it does a resistivity of around 2.5kΩ per square. So, a piece of graphene that is about 0.2mm long and 0.1mm wide gets us the required 5kΩ.
These early parts (we have just 3 pieces of encapsulated graphene to test) were quite expensive. So, as a bit of fun I thought we should look at the cost per mass, after the performance of this wonder material is often compared with other materials on a performance per weight basis (stronger than X by weight, more conductive than Y per weight), so why not cost. I did a quick “thumb-nail” calculation and came to the conclusion that graphene is about 4,000,000 times more expensive than its cousin diamond! The good news is that the price of graphene is likely to “mature” i.e. fall significantly as volumes increase and we really need very little (much less than a nano-gram, or even a nano-carat for those interested in diamonds).
So, now onto the interesting stuff as we start to assess graphene as a candidate material from which to make our JNT sensor.
