Customer demand for improved comfort, safety, convenience, reliability, fuel efficiency, infotainment and fun; and European legislation specifying stringent automotive emission targets are creating strong drivers for OEMs (Original Equipment Manufacturers) to increase the embedment of electronics in every aspect of the car. Position sensors are devices that convert linear or rotary motion into an electrical signal. They are applied to provide feedback on the motion of systems including velocity, acceleration, direction and position. Position sensors represent a key sensor that is used throughout the car to control: pedal position, crank position, steering wheel position, automotive gear selection, engine and vehicle stability management, and many other functionalities that involve movement. As cars become more intelligent, new applications for position sensors are being found delivering ever more complex features and functionalities (fuel level monitors, advanced engine management, dynamic headlight control). Furthermore as sensors involved in the management of the engine, position sensors represent a key technology in helping OEMs to meet legislative emission targets.

As the embedment of intelligence becomes common place, consumers increasingly expect these features as standard and at no extra cost. Such expectations create significant economic pressures across OEM supply chains. Furthermore, responding to consumer demand for enhanced reliability (and to gain differentiation), OEMs seek to offer consumers ever increasing warranty periods, with an objective of 7 years warranty. Such warranty period necessitate sensor systems with unprecedented levels of durability. To meet these drivers OEMs demand position sensors with:

1. Improved performance: enhanced monitoring and control of the vehicle
2. Lower sensor cost: greater use throughout the vehicle at minimal cost.
3. Increased durability, reliability and sensor lifetime: to enable reliable use over extended periods whilst maintaining accuracy.

Market and Consumer Benefits: The realisation of a low cost high performance positon sensor will help automotive OEMs to deliver ‘intelligence as standard’ whilst maintaining the highest standards of reliability. Such intelligence is a feature that will improve the competitive position of the UK automotive sector. Greater engine stability and control will also help OEMs to reduce engine emissions and avoid costly fines. From the consumer perspective such intelligence will enable greater comfort, safety, convenience, reliability, fuel efficiency, infotainment and fun. Reduced emissions will lead to a lower car/road tax. We believe the technology has the potential to realise up to 25% penetration (~£1.85 billion) into secondary markets (as detailed above), creating a wealth of opportunities for other sensor manufacturers and their supply chains and their customers.

Social Benefits:

1. Increased use and reliability of ‘intelligence’ (monitoring and control) within cars will lead to improved safety, comfort and convenience as standard
2. Reduced car emissions through greater engine stability and management will support government priorities with regards to reducing CO₂ emissions and other engine pollutants
3. Business growth within UK industry from graphene enabled materials will lead to new industry skills and jobs, including 76 directly from the Graphene Sens activities and securing many more through wider exploitation into secondary markets.

Environmental Benefits

1. Improved engine stability and control through use of advanced sensor systems will lead to reductions in vehicle emissions (1% reduction in emissions = 1.2m tonnes of CO2 within the UK [Dept. E&CC])

A transition from subtractive PCB to additive printed manufacturing processes will enable a reduction in solvent and heavy metal emissions

Utilising the unique properties of graphene formulated into nano-composite coatings, the Graphene Sens project will demonstrate feasibility for development of a highly innovative ‘graphene enabled’ potentiometer based position sensors (linear potentiometer sensor and encoder) achieving enhanced accuracy, lifetime and manufacturing cost efficiencies. The sensor solutions will comprise three key innovative components:

A graphene enabled potentiometer unit: the potentiometer will be manufactured using wear resistant graphene based inks with customised conductivities (resistivity’s). Customised conductivities will be achieved by synthesising inks with a range of resistivity’s (from 100 to 1000 Ω/m²) by adding non-conductive components to a base highly conductive graphene ink; and then blending the inks to achieve a tailored resistivity. Here it is believed that:

• the lubricating & enhanced wear characteristics of the graphene coatings will enable track lifetimes of greater than 10 million cycles using only a single track layer
• the enhanced conductivity of the graphene will enable the resistive track layer thickness to be reduced below 30µm (without compromising wear performance) enabling cost effective use of the graphene
• the atomically smooth surface of the graphene coatings will significantly reduce noise leading to greater sensor accuracy and reliability

The resistive track will be manufactured utilising thermally curable (and later UV curable) inks and a screen printing process enabling cost and energy efficient processing and the deposition of high viscosity inks (high particulate loading) resulting in densely packed and well consolidated material coatings.

Highly conductive formulations of the same graphene inks will also be considered for direct screen printing of the potentiometer conductive circuits onto bare circuit boards thereby enabling enhanced durability and further cost savings.