Portable Electroencephalogram Biofeedback Device Final Report Update: December 16PthP, 2005 BME 200 Team Members: Ashley Anderson III Christopher Wegener Ryan Thome Shikha Michele Lorenz Client: Daniel Muller Advisor: John WebsterTable of Contents §1. Abstract §2. Problem Statement §3. Introduction §4. Literature Search §5. Design Constraints §6. Proposed and Final Designs §6.1 Electrodes - Design Matrix - Modified Final Design - Electrolyte Solution §6.2 Amplifier §6.3 Feedback Method §6.4 Current Prototype §7. Design Testing §8. Future Work §8.1 Signal Acquisition §8.2 Signal Conversion to Feedback §8.3 Aesthetics §9. References §10. Product Design Specifications§1. Abstract Biofeedback is a therapy currently being researched to treat many psychological and physiological disorders. It is not known how attempting to control autonomic functions of the brain may help resolve abnormalities, but results overwhelmingly point towards biofeedback’s legitimacy. EEG biofeedback involves the monitoring and altering of brain activity and has been shown to effectively treat such problems as epilepsy, mood disorders, addictions, and attention-deficit/hyperactivity disorder. The majority of EEG biofeedback devices are designed for use in clinical situations by experience personnel. To apply this technology to a personal setting, an inexpensive and user-friendly device is required that can process brain signals and provide logical interpretations of the recorded activity. Several electrode types and feedback mechanisms, as well as a design for high-gain amplifiers, have been researched and analyzed. The current early prototype design and anticipated future work are also discussed. §2. Problem Statement The goal of our project is to design and build an inexpensive, portable electroencephalogram (EEG - brain wave monitor) that teaches meditation practitioners to achieve optimal meditation by the recognition and promotion of EEG alpha and theta waves. §3. Introduction Pharmacological therapies have been the standard way of treating most types of disorders and syndromes. However, alternative therapies are currently being prescribed by physicians as a new approach to healing and include such treatments as acupuncture, chiropractics, and biofeedback. These treatments’ mechanisms are not very well understood, but results demonstrate promising progress in patient rehabilitation. One of the most promising of these newly developed alternatives, biofeedback allows the user to view their own autonomic physiological changes. Physiological variation like pulse, blood pressure, respiratory rate, and brain activity can be monitored and eventually controlled through conscious practice of recognition and propagation of healthy ranges of such bodily functions.Our client, Dan Muller, M.D., Ph. D., frequently prescribes meditation as a means of mental health management. In order for inexperienced patients to learn how to meditate, a device is needed to tell the user exactly what type of activity their brain is currently undergoing. When meditation occurs, a specific frequency of waves is observed in the brain. Typical active brain waves are called beta waves and vary between 15-40 Hz. Relaxation and drowsiness are noted as alpha waves in the 8-15 Hz range. Meditation occurs in the theta waveform at 4-7 Hz. Figure 1. Raw EEG Data In order to monitor neuro-biofeedback, electroencephalographs (EEGs) are used to measure surface voltages on the scalp caused by neuron action potentials in the brain. These cellular action potentials directly relate to the qualitative and quantitative aspects of brain activity, reflecting the mental state within discrete frequency ranges. When the user can quantitatively observe the state that their brain is in, they can begin to coach themselves into lower frequencies of brain activity without the aid of a biofeedback device. This allows the user to achieve a theta waveform/meditation much faster and with greater ease in the future. With frequent use, EEG biofeedback has been shown to improve a variety of ailments such as addictions, mood disorders, epilepsy, and attention-deficit/hyperactive disorder (Raymond, 2005). §4. Literature Search A patent search revealed several methods (6,855,112; 5,450,855; 5,280,793) for regulating neural responses via monitoring them on a display for the purposes of biofeedback. Commercially available products are very expensive and are not typically EEG specific. For instance, the Stens NeXus-10 serves as an electroencephalogram (EEG), electrocardiogram (ECG), electromyogram (EMG), and slow cortical potentials (SCP). This device, while providing professional grade quality, will also run the buyer $4395. C2 and ProComp also manufacture high quality EEG biofeedback devices starting at about $2000.§5. Design Constraints The portable EEG (brain wave monitor) will take an incoming signal from a series of electrodes, amplify the signal to measurable and interpretable levels, filter out specific frequencies and present the occurrence of those distinctive brain waves in a manner applicable for biofeedback. The device should also be small and portable, have the ability to be used daily, have a relatively simple interface, and be comfortable, as it will be used while meditating. In order to conserve costs, internal and external parts need to be as simple and minimal as allowed. All aspects of the device need to be in compliance with AAMI and FDA standards and regulations for related devices. §6. Proposed Designs The EEG biofeedback device is actually an accumulation of three different areas of designs; electrodes for signal acquisition, an amplifier to create signal amplification and processing, and a biofeedback method for signal feedback. Described here are the individual designs for each. §6.1 Electrodes The previous years’ electrode design consisted of an elastic headband with two electrodes made of coiled wire folded over a felt surface and covered by another layer of felt. Another option that they mentioned was the use of an array of conducting probes which protrude through the hair to make direct contact with the scalp. As per their report, they could not get a good signal from these electrodes. Hence, in fall of 2005, we decided to develop a new design for the electrodes. The electrodes should be highly conductive, easy to use and inexpensive at the same time. In the process of
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