High density surface EMG system based on ADS1298-front end

High Density Surface Electromyography (HD-sEMG) is a non-invasive technique that allows measurement of the electrical activity with bidimensional array of electrodes. Besides the analysis in the time domain, it is possible to represent these signals in a topographic view enabling the investigation of single motor unit properties, as well as quantifying muscle fibre conduction velocity. Despite the complexity of acquisition systems for electromyographic signals, the availability of integrated circuits for specific applications, especially for biopotentials, e.g. ADS1298, provide simplified solutions for the development of this kind of equipment. The objective of this work is to develop a HD-sEMG system of 32 channels based on ADS1298. The developed system has a resolution of 298 nV, adjustable sampling rate (Fs) up to 2 kHz/channel and variable gain (G) from 1 to 12. In the system characterization tests, with G higher than one, the IRN (Input Referred Noise) parameter was approximately equal to 1 uVRMS, indicating a similar performance compared to a commercial device. However, this is not valid for unity gain. Furthermore, the system was tested in an experimental group obtaining the following signal results: ARV (Average Rectified Value) = 4.58±1.2 mV, RMS (Root Mean Square) = 30.0±16.9 uV and MNF (Mean Frequency) = 110.0±12.6 Hz. The results are within the normal range of values considering normative data and comparable works. Therefore, the developed system has the specifications for use in a wide scope of applications in electromyography research.