Design and Development of Surface Based Active EMG Sensor for Biomedical Applications

Abstract

The muscle in our body plays a vital and pivotal role in performing each minor task of routine activities. The action command is generated by the brain is executed by the human organ systems including Hands, legs etc. The messages are transmitted through motor neurons. The linkage of the muscle is based on the bone along with cords also called tissues. The contraction and relaxation of the muscle also causes tension in the tendons. The contraction of the muscle is possible due to the stimulation process in which exchange of the ions across the fiber of the muscle produces a voltage difference along with current in milliamps range. When the specific area of the muscle is targeted it’s called Electromyogram (EMG). The EMG signal are related to signal generated from the muscle of the human body, this signal is being widely used in clinical testing for the detection of any disorder. The involvement of the EMG signal detection is very common in the rehab centers in which those people they have lost hands/legs. An organ of the body indeed plays a role of backbone in the lives of amputees so that to recover that sense of confidence in the amputee’s artificial limbs are being developed to provide an ease in the lives of amputees. The broad classification of the EMG sensors are active and passive sensors. In the active sensor pre-amplification module is incorporated whereas, in the passive sensor only raw signal is obtained using piece of metals. In this research, the main objective is to design and develop a low cost and better performance sensor to obtain the signal from the muscle for the clinical testing and real time applications. In the developed sensor the EMG signal is extracted using stain less steel electrode. The obtained signal is further passed through the efficient band pass filter with cutoff frequencies as 10Hz to 150Hz. Once the signal is passed through the band pass filter the external noise factor got reduced to clearly visualize the EMG spectrum on a spectrum analyzer. The stage before the band pass filter is differential amplifier in which the signal is subtracted and enhanced using the gain of the amplifier. Once the signal got free from the external noises then notch filter with high Q-factor was applied to reduce the noise factor. The resultant signal contained reduced number of noise harmonics due to the incorporation of the notch filter design.