Figure: 1 PPG electrode placement Novel approach for Brain computer interfacing T. Gandhi 4 , A. Jena 1 , A. B. Pal 1 , D. Prusty 1 , P. Das 1 , S. Pandit 1 , R. Panda 2 , P. Pal 3 Abstract- Brain computer interfacing (BCI) plays an important role as an assistive device for various neural disorder people. In this paper, attempts have been made to interface thought process generated in photo plethysmography (PPG) with machine / computer. PPGs were collected by using PPG electrodes on finger tips corresponding to two types of brain activities; planning and relax. The proposed scheme is based on discrete wavelet transform (DWT) analysis. Features like entropy, energy and standard deviation at each node of the decomposition tree were calculated followed by application of SVM for classification. Clinical PPG signal recorded from planning as well as relax state are used to test the performance of this new scheme. The testing accuracy of this wavelet based SVM classifier is found to be 90% accurate .The proposed model is user friendly, cost effective and more accurate compared to its EEG counterpart. Key Words: Brain computer Interfacing (BCI); Assistive device; photo plethysmography (PPG); discrete wavelet transform (DWT). 1. INTRODUCTION Assistive technology is essential for the disabled and elderly to live independently for rest of their lives [1,8,9]. However accidentally disabled like spinal cord injury subjects, developmentally disabled individuals with motor paralysis; such as amyotrophic lateral sclerosis (ALS), Guillain–Barre Syndrome have difficulty in conveying their intentions, since the motor neurons influencing voluntary muscles are affected. Technology has made significant impact on social well-being of human beings who fall into the strata of disabled and paralytic people. In the past few years, the focus on the development of assistive devices for people with severe disability has increased by improving the traditional systems[9,10].Assistive technology deals with the development of technological hardware and software that enables physically challenged people to overcome the hindrances in carrying out activities of daily living. Recent development in embedded systems technology have opened up a vast area of research and development of portable and affordable assistive devices tuned to specific applications for the physically challenged populace [2,3,4]. Various assistive technologies supporting individual communication have been developed for the disabled using Brain-Computer interface (BCI) [5,6,7,11,12]. Researchers are incessantly trying to find out the individuals’ residual ability to supplement their impaired functions with surviving functions. Brain- computer interface (BCI) systems allow people to communicate without moving instead, direct measures of brain activity are translated into messages or commands. Hence, BCIs can enable communication for persons with severe motor disabilities that prevent them from communicating through other means. In this study, we have attempted to design an BCI system activated by photoplethysmograph (PPG) signals rather than electroencephalogram (EEG) signals, which is user-friendly, simple, cost effective. 2. MATERIALS AND METHODS 2.1 Plethysmograph is a combination of the Greek word, ’plethysmos’ meaning increase and ‘graph’ is the word for write. It is an instrument used mainly to determine and register the variations in blood volume or blood flow in the body. In this study we are introduce a method for Brain computer interface(BCI) using plethysmogram (PPG) signal 1 Biomedical Engg., MIET, BBSR, Orissa 2 Biomedical Engg., TAT, BBSR, Orissa 3 Biomedical Engg., NIT, Raipur 4 Biomedical Engg., AIIMS, New Delhi Corresponding Author: gandhitk@gmail.com 2010 First International Conference on Integrated Intelligent Computing 978-0-7695-4152-5/10 $26.00 © 2010 IEEE DOI 10.1109/ICIIC.2010.30 218