Epilepsy is an underlying tendency of the brain to produce sudden bursts of abnormal electrical activity resulting in debilitating seizures. Around 1 in 120 people in Europe, and 50 million people in the world suffer from epilepsy, but properly diagnosing, treating and managing it is very challenging.

The electroencephalogram, or EEG, is a classic method for measuring a person‟s brainwaves. Electrodes are placed on the scalp and detect the micro-Volt sized signals that result outside the head due to the synchronised neuronal action within the brain. Although to avoid misdiagnosis the EEG should never be used alone, it is a key diagnostic tool for answering the questions: is epileptiform discharge present?; what type of epilepsy is present?; and what is its locus within the brain? Because of its cost, a standard EEG test lasts between 20 and 30 minutes and so is generally restricted to recording interictal activity (activity that occurs between seizures). This results on misdiagnosis of up to 25%. Longer term monitoring, with an aim of recording seizure activity is required in cases which present diagnostic or management difficulty. Long term inpatient monitoring may be undertaken continuously for several days, significantly increasing the likelihood of seizures, or rare interictal activity, being recorded. However, the extra data produced can take a significant amount of time to analyse and the method comes with significant monetary and resource overheads. As a result it is not universally available. It also removes the patient from their natural environment which may have been a causative factor in the suspected seizure disorder due to the particular stimuli present. Ambulatory monitoring (AEEG) overcomes some of the limitations of inpatient monitoring with 24 hours of ambulatory monitoring being more than 50% cheaper than 24 hours of inpatient monitoring. Overall it is estimated that AEEG is clinically useful in 75% of patients, and abnormalities are found in 12-25% of AEEGs for which an inpatient EEG was normal or non-diagnostic. Whilst outpatient AEEG systems offer several benefits over long term inpatient monitoring, several limitations are still present:

  • There are issues in ensuring that the electrodes remain securely attached for the duration of the testing and also in the social acceptability of wearing head mounted electrodes in public.
  • Systems can weigh up to 1 kg, limiting their portability.
  • Each channel recorded requires a wired connection from the patient‟s head to the recording unit and the compliance of these wires can limit patient movement.
  • Long term recordings generate large amounts of data for storage or transmission, approximately 1 GB every 24 hours. This requires a significant amount of power.
  • The data is time consuming for a neurologist to analyse.

In the Wearable Technologies Lab we carry out research aiming to overcome these issues in order to create the ideal Wearable EEG (WEEG) for epilepsy. Our research targets aspects of WEEG system design, signal processing algorithms for automatic interpretation of the brain signals obtained from the sensors, and customized integrated circuit design leading to the overall miniaturization of the system.