BIOPOTENTIAL AMPLIFIER FOR SIMULTANEOUS OPERATION WITH BIOMAGNETIC INSTRUMENTS

A multichannel biopotential amplifier for simultaneous use with biomag netic measurements in a magnetically shielded room is designed and eva luated. Particular care is taken to make the amplifier electromagnetic ally compatible with the biomagnetic instruments over the whole freque ncy spectrum, from DO to RF. The electromagnetically quiet environment allows the use of high electrode impedances; the preamplifier has bee n designed accordingly. Special care is taken to analyse the coupling mechanisms of mains interference to the amplifier. Over 170 simultaneo us electric and magnetic recordings have been performed using the syst em in a hospital environment.