Hall effect transducer for apexcardiography and sphygmography

Area of Science:

• Biomedical Engineering
• Cardiology
• Medical Instrumentation

Background:

• Mechanograms, recordings of mechanical activity from internal organs and vessels, are crucial for non-invasive cardiac diagnostics (e.g., apex cardiograms).
• Existing mechano-electric transducers have limitations in self-adjustment and consistent pressure application, complicating measurements and calibration.

Purpose of the Study:

• To introduce a novel Hall-effect transducer for recording mechanograms.
• To evaluate the self-adjusting capabilities, constant touching pressure, and diagnostic accuracy of the new transducer.

Main Methods:

• Development and construction of a Hall-effect based mechano-electric transducer.
• Characterization of transducer properties: sensitivity (250 mV/mm), frequency bandwidth (0-45 Hz), linearity (+/- 1.5% over +/- 1.5 mm displacement).
• Clinical assessment on 27 patients with varying heart conditions, comparing results with other transducers.

Main Results:

• The Hall-effect transducer demonstrated self-adjustment and maintained constant touching pressure, simplifying the measurement process.
• Achieved high sensitivity, wide frequency bandwidth, and excellent linearity, with the ability to generate derivative signals.
• Clinical comparisons showed good detecting capability, correctness, and reproducibility of mechanograms (apexcardiograms, pulse waves).

Conclusions:

• The novel Hall-effect transducer provides a reliable and accurate method for non-invasive recording of cardiac mechanical activity.
• Its self-adjusting nature and consistent pressure application facilitate easier calibration and improve the quality of diagnostic data.
• The transducer shows significant potential for clinical application in cardiology, particularly for patients with heart defects.