This article provides insight in the difference between HD-EMG and Bipolar EMG.
With TMSi's amplifier SAGA, two different types of EMG measurements are supported: measuring EMG with bipolar electrodes, and High-Density EMG measurements. This article explains the difference between the two options. What type of EMG setup is most suitable depends on the intended use.
Bipolar EMG is a surface EMG (sEMG) technique that measures the difference in voltage between two electrodes on one muscle. Often, the SENIAM guidelines are followed and the electrodes are placed at a 2 cm distance from one another. This type of EMG measurement is often used to record the on-off switching of muscles and to estimate muscle force. Besides single bipolar or dual bipolar EMG sensors, TMSi also offers multi-channel EMG, where up to 32 bipolar pairs can be recorded. This can give insight into the activation of multiple muscles simultaneously.
High Density-EMG (HD-EMG) is a sEMG technique that measures muscle activity with multiple electrodes that are evenly spaced over an area of the skin. Different layouts of the electrode configuration over this area are possible, as described in this article. HD-EMG also allows spatial information to be recorded, besides temporal information. This method opens new possibilities to detect muscle characteristics like the evaluation of single motor unit action potentials.
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