Crosstalk Reduction in Forearm Electromyography During Static Gripping

Abstract

This paper presents the use of the branched electrode (BE) configuration to reduce crosstalk in forearm electromyography (EMG) during static gripping. The BE configuration is mathematically equivalent to the double differential configuration, only scaled down by a factor of two; however, the electrode configuration is advantageous due to its capability for being used with a conventional EMG device. The configuration was used to successfully record the bio-potential signal from five forearm muscles of one able bodied subject: Flexor Digitorum Superficialis, Flexor Digitorum Profundus, Flexor Carpi Radialis, Palmaris Longus and the Flexor Carpi Ulnaris. During the measurement process, a constant contraction strength of (50 ± 2.5)% maximum voluntary strength was enforced using a Smedley hand dynamometer. Two amplitude based indices were used to quantify the amount of crosstalk reduction: normalised root mean square (RMS) and normalised average rectified value (ARV). The BE configuration removed 4.82% (RMS) and 3.90% (ARV) of crosstalk from the flexor Digitorum Superficialis and 5.4% (RMS) and 3.47% (ARV) from the Flexor Carpi Ulnaris. The other three muscles had an increase in both the BE RMS and ARV, in comparison to their corresponding bipolar recordings. The low reduction in crosstalk (mostly an increase in both RMS and ARV) is believed to be from an electrode-skin impedance mismatch.