The write formula

BAE Systems and McLaren have teamed up to test a technology that allows engineers to ‘write’ electrical circuits directly on to surfaces. It could pave the way for simpler, lighter UAVs and help McLaren in its Formula 1 ambitions.


‘Direct Write’, developed by BAE deposits electrical wires, resistors and other electrical components in 3D on to conformable surfaces and has been extensively tested by McLaren at its Woking Technology Centre.


The system allows McLaren to write the electrical interconnections directly on to the car components, which has the benefit of giving the car a lower profile than if conventional wiring was used. This enhances the car’s aerodynamic qualities, which could potentially gain crucial fractions of a second for the team during a race.


Engineers have used a number of methods for printing the electrical wires on to the surfaces including using an inkjet, a micro-nozzle and even a micro-pen that literally allows the engineers to ‘write’ the circuit on to the surface.


A variety of materials can be printed, including conducting, insulating, magnetic, dielectric and optical materials. Silver particle inks are used for the conducting materials and insulating polymers help isolate the conducting tracks and protect them from damage.



Promising technology


Dr Jagjit Sidhu from BAE Systems’ Advanced Technology Centre in Filton near Bristol and the Direct Write project leader, said this is the first step for what appears to be a promising new technology. He said BAE Systems has been using Direct Write to link the load sensors on the car’s suspension.


‘The load cells on the car’s suspension are used to monitor downforce and other forces on the car, but at the moment the wiring for these sensors is obtrusive and not what you want trailing across aerodynamic surfaces,’ said Sidhu. ‘What we are doing is printing the wiring on to the body of the car so it is flush, less than 100 microns, against the surface.’


Sidhu said although BAE is only experimenting with the printed circuitry, there are also plans to move on to printing the sensors as well, and the company has received some DTI funding to develop this idea further.


‘The drive at McLaren is to integrate more sensors into the body of the car to gain more information on its performance, but once you add these sensors there is more weight which ruins the vehicle’s profile. What we are doing with this is simplifying the process and getting rid of unnecessary wires,’ he said.


McLaren is obviously benefiting from the partnership in terms of faster, lighter and more aerodynamic cars while BAE Systems is using the project to test technology that will eventually find its way back into the defence industry.


According to Sidhu, one of the main applications for the technology will be in keeping the weight down on aircraft, including UAVs. By printing the electronics — and eventually the sensors themselves — directly on to aircraft components a lot of space and weight could be saved.



Punishing conditions


Testing the Direct Write technology in the punishing conditions on board an F1 car also had its benefits. ‘On the car it is a very harsh environment so we are learning about how to protect the Direct Write wiring. Durability is one of the key questions for this technology,’ said Sidhu. ‘McLaren letting us test these technologies in a working field environment enables us to have a short cut in development.’


The technology is one of a number of projects to emerge from the McLaren/BAE partnership, which this year celebrates its 10th anniversary, including recent advances in carbon fibre techniques and wireless systems.


For Sidhu one of the main challenges of working with McLaren has been learning about fast turnaround times which is crucial for F1 success.

He said: ‘In F1 you need to develop the technology and apply it really quickly during a race season. The timescale is the challenge in developing the materials and technologies that are suitable for these applications — but it is something from which we are learning.’