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Bioelectrical signal acquisition

Electrical fields occur at various organs. Numerous biological functions of the human and animal body are controlled by electrical signals. This ranges from the excitation propagation in the nerves of the brain and the heart beat to the muscle movement. The signal strength is variable depending on the organ. A measurement of the electrical signals derived from the skin surface allows a non-invasive observation of various body functions. Essential bioelectrical measurement methods are:

• Electrocardiogram (ECG)
For the electrocardiogram (ECG), the changes of the electrical potential on the body surface in the region of the thoracic and extremities are derived. The development of these potentials is due to the excitation of the heart muscle (myocardium). By combining several derivatives, a vectorial ECG is obtained.

• Electroencephalogram (EEG)
For the electroencephalogram (EEG), changes of the electrical potential are derived from the cranial surface. The source of the potentials lie in the cerebral cortex. The origin of these potentials is due to the currents arising from synaptic processes in the cerebral cortex.

• Electromyogram (EMG)
For the electromygram, the changes of the electrical potential in the individual muscles or muscle groups on the skin surface are recorded. The origin of these potentials is due to the signals emitted by the nerves of the brain to control muscle activity.

• Bioimpedance measurement (IMP)
The bioimpedance measurement enables an assessment of the body’s properties by an active measurement of the reaction of the body tissue to an induced tension. These range from the determination of tissue composition to the observation of cardiac activity. The measurement is based on the different damping properties of different tissue types with regard to electrical alternating signals.
The reliability of the individual components of the preprocessing of the biological measuring chain is of crucial importance for the quality of the diagnoses based on the measurements. It consists of the biosensor (sensor/transducer), the signal filter and amplifier and the digital signal processing. In particular, the selection and placement of the measuring probe (electrode) on the body surface represents a challenge. Thorsis Technologies is involved in various research projects with the non-invasive detection and mobile processing of bioelectrical signals. Especially in the veterinary field the development of suitable dedicated solutions is still a technical challenge. Here, the company cooperates with veterinary and technical partners in telemetric solutions and the development of wearables in the large animal sector.