Estimation of stray coupling capacitances in biopotential measurements

MARCELO HABERMAN; AUGUSTO CASSINO; ENRIQUE SPINELLI

MEDICAL AND BIOLOGICAL ENGINEERING AND COMPUTING

SPRINGER HEIDELBERG

Lugar: HEIDELBERG; Año: 2011

0140-0118

Biopotential measurements are very sensitive toelectromagnetic interference (EMI) from power-lines.Interference conditions are mainly imposed by electric-fieldcoupling, whose effects can be described by coupling capacitances. The main of them are the patient-to-ground and thepatient-to-power-line capacitances, usually denoted as CB andCP, respectively. A technique to estimate these elements andexperimental data obtained in different environmental conditions are presented. It was found that CB ranges from hundreds of pF to nF, and CP from hundredths of pF to few pF. Thepresented technique also lets it know the small amplifier-toground and amplifier-to-power-line capacitances. Theknowledge of all these capacitances allows estimating theEMI conditions that biopotential amplifiers can be subject to,thus, resulting useful data for specifying their designrequirements and constraints in real working conditions