Graphene-enhanced position sensors solve all industry problems at once

Does the very high production cost of graphene mean that its potential cannot translate into actual benefits for commercial applications? Looking at a project such as GRAPHENESENS (Development of Graphene based Contact Position Sensors), we would be tempted to say no.

By using graphene-based nanocomposite coatings for the development of novel position sensors, the project has actually managed to overcome the three main disadvantages of current solutions: poor wear characteristics leading to long-term unreliability; limited accuracy because of surface roughness leading to noise; and high cost due to the use of precious metals to manufacture the sensor’s wiper.

All in all, the project has successfully created a new potentiometer unit with screen printed resistive tracks using graphene-based inks, a wiper head unit combining a low-cost substrate with a graphene-based coating, and a 48-pulse encoder base unit using notably a graphene-based barrier coating. The automotive and motorcycle markets are targeted, and prestigious brands are already queuing up.

Pufinji Obene, Operations Director at Precision Varionic International and coordinator of GRAPHENESENS, walks us through the project’s outcomes and its potential to change the position sensor market.

What did you aim to achieve with this project?

A lot of people talk about graphene itself and potential uses, but the truth is that graphene is quite expensive to use in its pure form. It means that breakthroughs using solely graphene will tend to take place only at lab scale.

But we also know that graphene has incredible properties, be it electrical conductivity, mechanical strength or smoothness. So we thought, why not look at an application-specific system, taking a pure graphene layer and manufacturing it into an ink formulation, and finally see the difference between the same application with and without graphene?

GRAPHENESENS focused on graphene for contact sensors in the automotive industry, but our research can find applications in position sensors of all kinds.

What added value did you hope graphene would bring to these products?

It was essentially about durability, especially if we are talking about graphene-enhanced sensors for the likes of antennas, accelerator pedals, encoders, motors or even robotics.

An accelerator pedal, for instance, requires long-life inks with specifications foreseeing 2 million cycles, and tests that see the system go through as many as 7 million cycles. The question is, can I use graphene to enhance the lifetime of this product? If I can, then adding just 1 or 2 % of graphene in an ink formulation – which is a very small percentage – can make a huge financial difference.

Would driverless cars be a potential application as well?

Yes. Self-driving cars use radomes to protect radars, but these tend to freeze over and therefore can’t get the signal in. So, one of the projects we are working on with one of our customers is to use our solution as a heating element. We coat polyamide with a low viscosity graphene ink that has very good adhesion to the substrate and high conductivity, so it can heat up the radome with very low power.

We mentioned durability as a strong advantage, but what about cost?

To get back to our contact position sensors, a game changing advantage is the fact that we can use our graphene to coat the potentiometer’s wiper. Usually a wiper would be made of a highly precious metal like Paliney, which is very expensive. By using a cheaper material and coating it with our graphene system, we can get a much cheaper (in the order of 5-10 times cheaper) wiper than we would have with Paliney.

We can actually use the graphene both on the tip of the cheaper wiper and for the potentiometer’s conductive circuit. This graphene to graphene interface allows us to have a perfect balance between the wiper’s wear characteristics and the electrical properties of the ink.

Were you able to quantify the benefits of this system?

We conducted a comparison between products with graphene and without graphene, and the benefits are tremendous. We were able to halve the thickness of the printed ink, and our Aerosol Assisted Ion Deposition (AAID) technique to coat the cheaper wiper reduces its cost by 80 %. Overall, we managed to get a 45 % cost reduction in making contact sensors.

How about your plans for commercialisation?

We are already making prototypes for two or three automotive suppliers strictly on the wiper side, and two of them are also working on the long-life ink, but that’s confidential in terms of IP.

Some of our customers have issues on the wiper side and they need the new product as soon as possible. Now the challenge is to reach an industrial production scale, and we will have to go for an SME Instrument phase 2 project to make this possible.

We are also contemplating other markets besides automotive, so all in all, we hope to have something on the market within the next two-three years.

Looking back, would you say that your project is a case in point of what can be achieved with graphene?

I think it is. Right now the market requires applications of graphene for real-life scenarios. I don’t think graphene is ever going to be useful for society in its pure form until we can take a single layer of it and place it onto a circuit board. In the meantime, we should use graphene as an enhancer and focus on making practical products. This is what we did with GRAPHENESENS.