Array sensor for arterial pulse recording-reduction of motion artifact

A linear array of three high sensitivity piezoelectric crystals are spaced 0.75 cm apart and bonded to a plastic block. The crystals are used in the thickness compression mode to measure the pressure pulse. The signal from each crystal is amplified and processed for noise reduction. The array is aligned perpendicular to the artery, and information from the off-axis sensors is averaged and subtracted from the on-axis signal. In addition, the sensors are aligned on-axis for determination of blood velocity from the phase difference between sensors. Experimental results indicate that motion artifact is mostly common-mode and that the contact stress on the surface of the skin is therefore uniform. Preliminary cancellation techniques provided are simple yet effective in restoring disturbed pulse recordings