Detection and Conditioning of Surface EMG Signals

This chapter presents the detection and conditioning of surface electromyographic (EMG) signals. More advanced techniques are now widely used in research laboratories and are being adopted in clinical settings. Such techniques are based on multichannel detection by means of one dimensional (1-D) or two dimensional (2-D) electrode arrays. The chapter describes the electrode-skin interface and the front-end amplifier stage. The impedance between two electrodes is the sum of two electrode-skin impedances plus the interposed tissue impedance. Conventional electrodes, either wet or dry, behave like transducers converting ionic current (in tissue and gel) into flow of electrons in the metal. These electrical sensors require a careful skin preparation to reduce the impedance and noise associated to this interface. The biomedical sector offers small-sized, high-cost application-specific integrated circuits (ASIC) devices for biopotential measurements. Applications are expected to range from physiopathological investigations, to rehabilitation games, biofeedback applications, and sport training.