HIGH RESOLUTION DATA ACQUISITION SYSTEM FOR BRAIN IMAGING

Abstract

The U.S. has 12.3% disabled people based on the American Community Survey (ACS) in 2012. According to this survey, more than half of the disabled population suffers from ambulatory disabilities. Therefore, a system which enables people with disabilities to control their environments is crucially important. Moreover, ubiquitous physiological monitoring will be a key driving force in the upcoming medical revolution. Cardiac and brain signals in the form of electrocardiograms (ECGs) and electroencephalograms (EEGs) are two critical health indicators that directly benefit from long-term monitoring. Brain-computer interfaces (BCIs) are systems that detect changes in brain signals related to human intentions, typically translating intention into a control signal to communicate between the brain and the external world such as a computer. The tripolar concentric ring electrode (TCRE) has shown to be sensitive enough to visualize the electrical impulses that correspond to a person’s specific thought pattern. Therefore, this electrode has the potential to enable people who are paralyzed to use their thoughts to control their phone, television or other things in their environment. The TCRE has been built and was successfully tested. However, at this step of its development, long coaxial cables are required to connect the electrodes to the preamplifier. The preamplifier is a big box with 24 channels (for 24 electrodes), although not all channels are always used. Despite technologically advancements and electronic miniaturization, the use of current EEG monitoring is limited by inconvenience and discomfort. Thus, having an active TCRE EEG electrode that can record the signal, digitize it and send the data to the host computer for further processing is helpful. Such a system not only preserves the advantages of the TCRE electrode, but also takes advantage of today’s advancement in microelectronics. This renders the electrode more comfortable and convenient to be used in real life situations. Therefore, the EEG acquisition board has to be miniaturized so that it fits on the electrode. The small board can also be duplicate many times to meet the needs of a specific EEG recording application. Our approach to build an active TCRE acquisition system (digital TCRE) involves two steps: Step 1: create a mathematical model of the electrode, electrolyte, and body may contribute to a better understanding of how biomedical signals are obtained by electrodes. Good design starts with clearly understanding and defining interface requirements and developing accurate equivalent circuit models of all components involved. In order to understand the behavior