EPIC new era for electric sensors
A groundbreaking new contactless sensor technology developed at Sussex has been nominated for multiple innovation awards and is set to revolutionise the way we look at the world around us from detecting heart rates to dating fingerprints.
Professor Robert Prance and his team at the Centre for Physical Electronics and Quantum Technology have developed an Electric Potential Sensor (EPS) that can detect changes in electric fields. It was announced last week that the commercial version of the sensor has been short-listed for awards in three categories of the prestigious 2011 Institute of Engineering Innovation Awards which will be announced in November.
The basic sensor was developed to address limitations of the technology available for measuring electrical potential. Conventional voltmeters make a circuit with the source they are measuring and can modify it. Professor Prance’s team have created a circuit using a combination of well-known techniques and novel ‘feedback loops’. Some of the science behind the EPS was originally developed in the 1950s for photocopiers but abandoned. The new integrated circuit provides a robust, stable, sensitive sensor that isn’t susceptible to damage by electrostatic discharge, eliminates background electrical ‘noise’ and does not modify the electrical potential it is measuring.
The basic design can be tailored to measure across different spatial and electrical scales and can detect changes in electrical activity from a distance or through walls. It can be produced cheaply and requires a very low power source so is highly portable. Most importantly EPS technology can detect changes in the earth’s electric field, measure electrical activity produced within the human body and record electrostatic charge created when materials interact.
In December 2010, the team joined up with electronics specialists Plessey Semiconductors to make the sensor commercially available. Dubbing the technology the Electric Potential Integrated Circuit (EPIC) Plessey has concentrated initially on medical diagnostics but its potential applications are wide ranging. The EPIC sensor has already received a ‘Best of Sensors Expo 2011’ Gold Award in June.
You may not even be aware that the earth has an electric field but the charge above the surface increases by 100 volts per meter. Because we are made predominantly of water our movements cause changes in these fields that the EPS can detect. Professor Prance’s team can remotely record a person’s movements or identify hand movements. It could be used, for example, to locate people in a smoke filled room before entering. As a motion detector it will be further developed for fitness monitoring, security, the automotive industry and to control televisions and computers. In June, the Research Councils UK Big Ideas for the Future Report showcased EPS technology used to track movement in performance sports as one of the most important projects taking place in UK universities.
We produce electrical charge in the form of nerve impulses. For example, electrical currents flow when the powerful heart muscle in our chest receives nerve impulses that cause it to contract and relax. These are commonly visualised as the spiked trace on an ‘electrocardiograph’ (ECG).
EPIC sensors placed on the hands or over clothes provide an accurate trace and an ECG monitor has just become commercially available through Plessey. Conventionally multiple disposable electrodes are attached to the body with conducting gel. The EPIC sensor is used dry and can be re-used making it easier, quicker and more cost effective. They could even be integrated into stretchers to give instant readings or worn long term to monitor how the heart works during everyday activities.
The team at Sussex have also shown that, using sensors on the head, different key brain waves can be detected without gels and abrasion of the skin. The resolution of the ‘electroencephalogram’ (EEG) produced could allow us “to record identifiable signals against know thought patterns” according to Dr. Sean Connor of Plessey. This opens up possibilities for using EEG in neuroscience only currently imagined in science fiction.
By placing the probes on skeletal muscles, they can be used to record an ‘electromyograph’ for diagnosing and monitoring conditions that effect movement. Or, by identifying patterns from certain muscle groups, it would be possible to create man-machine interfaces. A probe on the skin could control an artificial limb or, for quadriplegics, sensors around muscles over which they still have voluntary control could provide fast, efficient manipulation of equipment.
Of particular interest at Sussex is the possibility to use EPIC sensors to measure signals from electrical activity of eye muscles. An ‘electrooculograph’ (EOG) depicts unique signatures of eye movement, changes which could indicate physiological or neurological disorders. Investigators in the School of Psychology currently use video eye tracking to investigate links between cognitive impairment and oculomotor dysfunction. It’s early days yet but Dr. Sam Hutton, Senior Lecturer in Experimental Psychology and Miss Natasha Steinhausen of the School of Engineering and Design are discussing how to compare these technologies.
Earlier this year the team reported the use of tiny EPS sensors six millionths of a meter across to detect electric charge left by our fingers on insulating materials like plastics. When different materials are placed in contact and then separated charged electrons are transferred: think of rubbing your feet on a carpet and giving an electric shock. The presence or absence of electrical activity can be spatially mapped to create an image. This is non destructive so DNA and other chemical analyses can still be conducted. The electrostatic signature of the fingerprint decays over time potentially allowing dating relative to when a crime was committed, something that cannot currently be achieved.
Although this article mentions only a few of the applications already imagined it is clear that excellence in fundamental research and a visionary commercial development programme will be securing more awards for the team in the future. As Professor Bob Allison, Pro-Vice-Chancellor (Research), says: “This technology could impact widely on quality of life, safety and security, wealth generation and new research tools by providing affordable healthcare solutions.”