Single Channel Electrooculography Based Human- Computer Interface for Physically Disabled Persons Partha Pratim Banik 1 , Md. Kawsar Azam 1 , Chayan Mondal 1 , and Md. Asadur Rahman 2 1 Department of Electrical and Electronic Engineering 2 Department of Biomedical Engineering Khulna University of Engineering & Technology (KUET), Khulna-9203, Bangladesh Email: ppbanik006@gmail.com, anikkuet1003073@gmail.com, bappaia.mondal@gmail.com, eeeasadur@gmail.com Abstract—Most of the paralyzed or physically disabled persons are unable to communicate with others, easily. To minimize this problem, different types of Human-Computer Interface (HCI) systems have been developed in recent years. In this paper, a single channel electrooculography (EOG) based HCI system has been proposed to increase the communication ability as well as quality of life for paralyzed persons who cannot speak or move their limbs. The extracted EOG signals are processed by our EOG acquisition system and sent it to a microcontroller unit which processes those signals for interfacing with computer via serial communication. A Graphical User Interface (GUI) is designed using MATLAB which contains some buttons to help a user to express what he/she wants through messages. A liquid crystal display (LCD) is used to show the messages. Our experimental results show that the maximum and minimum average time recorded for selecting 10 buttons for a particular user are 4.27 and 4.11 second, respectively. Particularly for selecting a button, the maximum and minimum average time recorded by every user are respectively 5.58 second and 1.82 second. We have found that the average button selection accuracy is around 95%. Keywords—EOG signal, human-computer interface (HCI), single channel electrode, button selection algorithm, microcontroller, graphical user interface (GUI). I. INTRODUCTION A. Background Paralysis is a loss of muscle function in any part or organ of body that prevents a person from his normal operation. People suffering from amyotrophic lateral sclerosis (ALS) [1], [2], brainstem stroke, brain or spinal cord injury, cerebral palsy, muscular dystrophies, multiple sclerosis, etc. [2], lose correct response of their limbs as well as deprive of their ability to speak. Most of the cases their eyes, mind, brain are active for response and those active parts can be used to communicate with others by developing various types of biological signal based applications. Nowadays, a great problem is occurred to rehabilitate several physically disabled persons. For this reason, it has become a burning demand to design a low cost automated system which can help a handicapped person to communicate with others. In recent years, various research groups around the world have set up many researches on electroencephalography (EEG), electrooculography (EOG), electrocardiogram (ECG), and electromyogram (EMG) to allow the disabled persons more comfortable, autonomous and independent lifestyle [3]. EOG signal is a convenient signal than any other bioelectrical signals (EEG, EMG, ECG) because of its easy waveform detection mechanism and linear relationship between EOG and ocular movement [4], [5]. There are many types of applications of EOG signal and most of the applications are noninvasive and quite convenient for user. B. Related Work and Research Scope EOG signal was first observed by the German physician Emil du Bois-Reymond in 1848 [6]. There are several technologies for developing eye movement based assistive devices such as camera, special contact lens, EOG potential and so on [7]. A communication system with improved speed and accuracy is designed and developed by controlling eight- directional ocular movements [8], [9]. Some novel efficient EOG based virtual keyboard [10], [11] and wireless EOG signal classification algorithm [1] are designed by using multichannel electrodes to control HCI system. A single channel EOG based system is designed in [12] where only horizontal electrode is used which is a prototype design for moving a robotic car through moving eye. Authors in [1], [8]-[10] have used multichannel electrodes for extraction of EOG signals. Nonetheless, it has become very uncomfortable condition for a user to place multichannel electrodes around the face. The development of various methods of eye movement (e.g. blinking of eye, different sequence of horizontal ocular movement etc.) through EOG signal is the best way to replace multichannel electrodes by single channel electrode. Therefore, there arise a scope to design a single channel user friendly HCI system. C. Contribution The goal of this research work is to design an EOG based embedded system with single channel electrode through which the paralyzed person can communicate with others by showing messages through a Liquid Crystal Display (LCD). Only horizontal movement of eye is necessary for this system. We have designed a software that contains some buttons which can be selected by using a sequence of horizontal ocular movement. By clicking buttons, the corresponding message for the button is sent to the LCD.